Routine intraoperative ureteric stenting for kidney transplant recipients

Abstract

Background

Major urological complications (MUCs) after kidney transplantation contribute to patient morbidity and compromise graft function. The majority arise from vesicoureteric anastomosis and present early after transplantation. Ureteric stents have been successfully used to treat such complications. A number of centres have adopted a policy of universal prophylactic stenting at the time of graft implantation to reduce the incidence of urine leaks and ureteric stenosis. Stents are associated with specific complications, and some centres advocate a policy of only stenting selected anastomoses. This is an update of our review, first published in 2005 and last updated in 2013.

Objectives

To examine the benefits and harms of routine ureteric stenting to prevent MUCs in kidney transplant recipients.

Search methods

We contacted the Information Specialist and searched the Cochrane Kidney and Transplant's Specialised Register (up to 19 June 2024) using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Registry Platform (ICTRP) Search Portal, and ClinicalTrials.gov.

Selection criteria

Our meta‐analysis included all randomised controlled trials (RCTs) and quasi‐RCTs designed to examine the impact of using stents for kidney transplant recipients. We aimed to include studies regardless of the type of graft, the technique of ureteric implantation, or the patient group.

Data collection and analysis

Summary estimates of effect were obtained using a random‐effects model, and results were expressed as risk ratios (RR) and their 95% confidence intervals (CI). Confidence in the evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach.

Main results

Twelve studies (1960 patients) were identified. One study was deemed to be at low risk of bias across all domains. The remaining 11 studies were of low or medium quality, with a high or unclear risk of bias in at least one domain.

Universal prophylactic ureteric stenting versus control probably reduces major urological complications (11 studies: 1834 participants: RR 0.30, 95% CI 0.16 to 0.55; P < 0.0001; I² = 16%; moderate certainty evidence; number needed to treat (17)); this benefit was confirmed in the only study deemed to be at low risk of bias across all domains. This benefit was also seen for the individual components of urine leak and ureteric obstruction. Universal prophylactic ureteric stent insertion reduces the risk of MUC in the subgroup of studies with short duration (≤ 14 days) of stenting (2 studies, 480 participants: RR 0.39, 95% CI CI 0.21 to 0.72; P = 0.003; I² = 0%) and where stenting was continued for > 14 days (8 studies, 124 participants: RR 0.22, 95% CI 0.08 to 0.61; P = 0.004; I² = 29%).

It is uncertain whether stenting has an impact on the development of urinary tract infection (UTI) (10 studies, 1726 participants: RR 1.32, 95% CI 0.97 to 1.80; P = 0.07; I² = 60%; very low certainty evidence due to risk of bias, heterogeneity and imprecision). Subgroup analysis showed that the risk of UTI did not increase if short‐duration stenting was used (9 days) and that there was no impact on UTI risk when the prophylactic antibiotic regime co‐trimoxazole 480 mg/day was used. Stents appear generally well tolerated, although studies using longer stents (≥ 20 cm) for longer periods (> 6 weeks) had more problems with encrustation and migration.

There was no evidence that the presence of a stent resulted in recurrent or severe haematuria (8 studies, 1546 participants: RR 1.09, 95% CI 0.59 to 2.00; P = 0.79; I² = 33%). The impact of stents on graft and patient survival and other stent‐related complications remains unclear as these outcomes were either poorly reported or not reported at all.

Authors' conclusions

Routine prophylactic stenting probably reduces the incidence of MUCs, even when the duration of stenting is short (≤ 14 days). Further high‐quality studies are required to assess optimal stent duration. Studies comparing selective stenting and universal prophylactic stenting, whilst difficult to design and analyse, would address the unresolved quality of life and economic issues.

Plain language summary

Routine prophylactic stenting reduces the incidence of major urological complications in kidney transplant recipients

Key messages

‐ The incidence of major urological complications was reduced by inserting a stent during kidney transplant surgery.

‐ Stent insertion reduces the risk of major urological complications even when the stent is only left in place for a short period of time after transplant (≤ 14 days).

‐ The impact of stenting on urinary tract infections was uncertain. However, when the stent was only left for a short period, or people were on preventative antibiotics, stenting did not increase the number of urinary tract infections.

What is kidney failure, and how should it be treated?

Kidney failure occurs when a person's kidneys no longer function well enough to keep them alive. Kidney transplantation is the treatment of choice for kidney failure, improving quality of life and extending the recipient's life expectancy. Interventions aimed at reducing the burden of post‐transplant complications are a major area of research in the transplant community.

The ureter (drainage tube for urine) from the donated kidney needs to be joined to the recipient's bladder during surgery. Major urological complications (e.g. urine leak and blockage) can occur following transplantation. These happen at the location of this join.

What did we want to find out?

We wanted to determine the benefits and harms of routine stenting (adding a temporary plastic tube to this join) in kidney transplant recipients to prevent major urological complications.

What did we do?

We searched for all trials that assessed the benefits and harms of randomly allocating transplant recipients to receive a stent during surgery or not. We compared and summarised the trials' results and rated our confidence in the information based on factors such as trial methods and size.

What did we find?

We included 12 studies involving 1960 transplant recipients. The number of major urological complications was reduced by using a stent. Stent insertion also reduces the risk of major urological complications even when the stent is only left in place for a short period of time after transplant (≤ 14 days).

The impact of stenting on urinary tract infections was uncertain. However, when the stent was only left in place for a short period, or people were on preventative antibiotics, stenting did not cause more UTIs. The presence of a stent did not appear to increase blood in the urine. More studies are needed to investigate the use of selective versus universal prophylactic stenting for the unresolved issues of quality of life and cost.

What are the limitations of the evidence?

We are reasonably confident that inserting a stent during kidney transplantation reduces the number of major urological complications. We are less certain of the results for the number of urinary tract infections, the effect on patient and kidney survival, increased blood in the urine, quality of life, and the overall cost.

How up‐to‐date is the evidence?

The evidence is current to June 2024.

Summary of findings

Summary of findings 1. Summary of findings table ‐ Stent compared to no stent for kidney transplant recipients.

Stent compared to no stent for kidney transplant recipients
Patient or population: kidney transplant recipients Setting: all settings Intervention: stent Comparison: no stent
Outcomes	Anticipated absolute effects* (95% CI)		Relative effect (95% CI)	№ of participants (studies)	Certainty of the evidence (GRADE)	Comments
	Risk with no stent	Risk with stent
Major urological complications: combined urine leak and obstruction follow‐up: median 3 months	96 per 1000	29 per 1000 (15 to 53)	RR 0.30 (0.16 to 0.55)	1834 (11 RCTs)	⊕⊕⊕⊝ Moderate	Stenting probably results in a large reduction in MUC, combined urine leak, and obstruction. Overall, there is moderate certainty of evidence due to the risk of bias. However, the single study deemed low risk of bias across all domains confirmed that prophylactic stenting reduces MUC incidence.
Urine leak follow‐up: median 3 months	52 per 1000	13 per 1000 (6 to 29)	RR 0.26 (0.12 to 0.56)	1834 (11 RCTs)	⊕⊕⊕⊝ Moderate	Stenting probably results in a large reduction in urine leak specifically. Moderate certainty of evidence due to a notable high risk of bias in specific domains across the studies involved
Ureteric obstruction follow‐up: median 3 months	47 per 1000	22 per 1000 (12 to 41)	RR 0.47 (0.25 to 0.87)	1726 (10 RCTs)	⊕⊕⊕⊝ Moderate	Stenting probably results in a large reduction in ureteric obstruction specifically. The certainty of evidence is moderate due to the notable high risk of bias in specific domains across the studies involved.
Urinary tract infection follow‐up: median 3 months	171 per 1000	226 per 1000 (166 to 308)	RR 1.32 (0.97 to 1.80)	1726 (10 RCTs)	⊕⊝⊝⊝ Very low	It is uncertain whether stenting impacts the development of UTIs. There is very low certainty of evidence due to the risk of bias, imprecision, heterogeneity, and inconsistencies in UTI definitions across the studies.
Haematuria follow‐up: median 3 months	92 per 1000	100 per 1000 (54 to 183)	RR 1.09 (0.59 to 2.00)	1546 (8 RCTs)	⊕⊕⊝⊝ Low	There is an indication of the likely effect that stents increase haematuria incidence. However, the likelihood that it will be substantially different is high. Low certainty of evidence due to inconsistencies in definitions of pathological haematuria compared to 'expected haematuria' post‐kidney transplant.
Graft survival follow‐up: median 3 months	0 per 1000	0 per 1000 (0 to 0)	Not estimable	(5 RCTs)	‐	Meta‐analysis was not possible. The effect of stenting on graft survival is uncertain.
Patient survival follow‐up: median 3 months	0 per 1000	0 per 1000 (0 to 0)	Not estimable	(7 RCTs)	‐	Meta‐analysis was not possible. The effect of stenting on patient survival is uncertain.
Other stent‐related complication follow‐up: median 3 months	0 per 1000	0 per 1000 (0 to 0)	Not estimable	(8 RCTs)	‐	Meta‐analysis was not possible. The effect of stenting on causing stent‐related complications is uncertain.
*The risk in the intervention group (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI). CI: confidence interval; RR: risk ratio
GRADE Working Group grades of evidence High certainty: we are very confident that the true effect lies close to that of the estimate of the effect. Moderate certainty: we are moderately confident in the effect estimate: the true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different. Low certainty: our confidence in the effect estimate is limited: the true effect may be substantially different from the estimate of the effect. Very low certainty: we have very little confidence in the effect estimate: the true effect is likely to be substantially different from the estimate of effect.
See interactive version of this table: https://gdt.gradepro.org/presentations/#/isof/isof_question_revman_web_445507866615509207.

Background

Description of the condition

Kidney transplantation is the treatment of choice for people with kidney failure. Transplantation improves both quantity and quality of life (QoL) for recipients. Currently, and for the foreseeable future, kidney graft demand greatly exceeds supply. A large body of research is developing strategies to expand the donor pool and increase the supply of organs. Concurrently, other groups are looking at ways to extend the life of kidney grafts by both reducing the burden of chronic allograft nephropathy and reducing the number of recipients dying with functioning grafts. There remains a small percentage of grafts lost in the early months post‐transplantation to acute rejection and technical complications, including vascular thrombosis. Major urological complications (MUCs) mostly originate from the vesicoureteric anastomosis, present early after transplantation (within three months) (Kumar 2004) and contribute to patient morbidity, graft loss and death (Rigg 1994; Thomalla 1990). The first kidney transplants were anastomosed using a transvesical approach (Merrill 1956). This technique, now more commonly known by the eponym Leadbetter‐Politano (L‐P) (Politano 1958), has been generally superseded by the extravesical ureteroneocystostomy (Lich‐Gregoir) (L‐G) (Konnak 1972) which is less technically demanding. Despite this, there remains significant morbidity, with a review of case‐control studies reporting mean incidences of between 3% and 5% (Mangus 2004).

Vesicoureteric complications present either as urine leaks or collecting system obstruction. In the absence of technical complications, ureteric ischaemia (often related to the retrieval procedure) is thought to be chiefly responsible for the early ureteric complications post‐transplantation (Karam 2004). Both ureteric leak and obstruction have been successfully treated with "double‐J" stent insertion, prompting surgeons to contemplate the use of prophylactic stents (Insall 1995).

Description of the intervention

Stents have been successfully used in general urological practice for decades. The double‐J stent consists of a straight tube with anchoring "j" loops at either end. In conventional urological practice, the stent is straightened and inserted over a guidewire either via a cystoscope and/or under radiological guidance. Removing the guidewire causes both ends to curl into their natural anchoring conformation. Placement of a stent during transplantation is a relatively simple procedure and requires no additional instrumentation or imaging. However, a further procedure to remove the stent is always required, may be inadvertently delayed, and incurs further healthcare costs.

How the intervention might work

Conventional native ureteric repairs over stents are widely accepted to have a better outcome (Turner 1982). In addition, they have been successfully used in pyeloplasty, ureterovesical reconstruction and the management of stone disease (Baum 1982; Finney 1978). The therapeutic benefits of stents in transplantation are still disputed but may include simplifying the creation of a watertight ureteric to bladder anastomosis and reducing anatomical kinking (French 2001; Kumar 2004). The most significant theoretical complication is an increase in the number and severity of urinary tract infections (UTIs). Other possible complications include persistent haematuria and bladder discomfort, stent migration, breakage, encrustation and complications during removal.

Why it is important to do this review

A number of centres have adopted a policy of prophylactic stent insertion with endoscopic removal at a designated time post‐transplantation in an effort to reduce the MUC rate (Lin 1993). However, it has been suggested that a tension‐free anastomosis with an intact blood supply is the only effective strategy to avoid both early and late ureteric complications, and the benefits of prophylactic stenting are outweighed by their possible complications. As a consequence, many units continue to selectively stent only difficult anastomoses or in circumstances where the vesicoureteric viability may be additionally compromised (Thomalla 1990).

Objectives

This review aimed to examine the benefits and harms of routine ureteric stenting to prevent urological complications in kidney transplant recipients.

Potential benefits

• Reduction in the incidence of MUCs.

Potential harms

• Increase in the incidence of UTI and haematuria

• Idiosyncratic complications (migration, malposition, irritation, encrustation)

• Complications from stent removal.

Methods

Criteria for considering studies for this review

Types of studies

All randomised controlled trials (RCTs) and quasi‐RCTs (RCTs in which allocation to treatment was obtained by alternation, use of alternate medical records, date of birth or other predictable methods) looking at the use of stents to prevent urological complications.

Types of participants

Inclusion criteria

We included all studies designed to examine the impact of the use of stents in kidney transplant recipients. Specifically, we aimed to include studies regardless of the type of graft (live donor, cadaveric), the technique of ureteric implantation (extravesical, transversal), and patient group (paediatric, elderly, multiple organs, and previous transplant recipients).

Studies were assessed against a number of criteria, including the demographics of organ donors and recipients, surgical techniques, and medical management, to allow comparison and stratification for known MUC risk factors.

Exclusion criteria

Our protocol stipulated specific exclusion criteria, including studies detailing the analysis of horseshoe kidneys, patients with abnormal bladder function, and urinary diversion.

Types of interventions

For a study to be included, one randomised group of graft recipients must have had the vesicoureteric anastomosis stented at the time of implantation with a suitable prosthesis.

Types of outcome measures

Primary outcomes

Urological complications related to the transplant ureter (urine leak/obstruction) within three months of transplant.

Secondary outcomes

• Graft survival

• Patient survival

• Incidence of UTI

• Incidence of haematuria

• Other stent‐related complications: irritative symptoms, breakage, migration/malpositioning, encrustation, forgotten, expulsion

• Complications from stent removal

Search methods for identification of studies

Electronic searches

We searched the Cochrane Kidney and Transplant Register of Studies up to 19 June 2024 through contact with the Information Specialist using search terms relevant to this review. The Register contains studies identified from the following sources.

• Monthly searches of the Cochrane Central Register of Controlled Trials CENTRAL

• Weekly searches of MEDLINE OVID SP

• Hand searching of kidney‐related journals and the proceedings of major kidney and transplant conferences

• Searching of the current year of EMBASE OVID SP

• Weekly current awareness alerts for selected kidney journals

• Searches of the International Clinical Trials Registry Platform (ICTRP) Search Portal and ClinicalTrials.gov.

Studies contained in the Register are identified through searches of CENTRAL, MEDLINE, and EMBASE based on the scope of Cochrane Kidney and Transplant. Details of search strategies, as well as a list of handsearched journals, conference proceedings and current awareness alerts, are available in the Specialised Register section of information about Cochrane Kidney and Transplant.

See Appendix 1 for search terms used in strategies for this review.

Searching other resources

1. Reference lists of nephrology textbooks, review articles and relevant studies.

2. Letters seeking information about unpublished or incomplete trials to investigators known to be involved in previous studies.

Data collection and analysis

We performed this review in line with recommendations from the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2022).

Selection of studies

The review was carried out initially by three authors (CHW, AAB, DMM) and a fourth (DAR) was consulted for a specific urological transplant opinion. This update was conducted with the inclusion of two new authors, SJT and LGP. The search strategy described was used to obtain titles and abstracts of studies that may have been relevant to the review. The titles and abstracts were screened independently by LGP and SJT, who discarded studies that were not applicable. Both primary authors independently assessed the retrieved abstracts and determined which studies satisfied the inclusion criteria. Data extraction was carried out by the same authors independently using standard data extraction forms. Further information required from the original author was requested by written correspondence, and relevant information obtained in this manner has been included in the review. The inclusion of studies was then discussed and agreed upon by a senior author, CHW.

Data extraction and management

Data extraction was carried out independently by two authors using standard data extraction forms. Where more than one publication of one study existed, reports were grouped together, and the publication with the most complete data was used in the analyses. Where relevant outcomes were only published in earlier versions, these data were used.

Assessment of risk of bias in included studies

Each paper was independently assessed by two authors (LGP and SJT), and any disputes were settled by a senior author (CHW) (see Appendix 2). For each of the following domains, a result of 'High', 'Low', or 'Unclear' was determined, and the reasoning for this judgement was commented upon.

• Was there adequate sequence generation (selection bias)?

• Was allocation adequately concealed (selection bias)?

• Was knowledge of the allocated interventions adequately prevented during the study?

  • Participants and personnel (performance bias)

  • Outcome assessors (detection bias)

• Were incomplete outcome data adequately addressed (attrition bias)?

• Are reports of the study free of suggestion of selective outcome reporting (reporting bias)?

• Was the study apparently free of other problems that could put it at risk of bias?

Measures of treatment effect

Outcomes were expressed as risk ratio (RR) with 95% confidence intervals (CI) where appropriate. Absolute risk reductions are given as numbers needed to treat (NNT), a figure that quantifies the number of patients that must be stented to prevent one MUC. Data was pooled using the random‐effects model, but the fixed‐effect model was also analysed to ensure the robustness of the model chosen and susceptibility to outliers during subgroup analysis. Adverse effects were collated and reported in tabular form.

Unit of analysis issues

We did not encounter any issues with unit of analysis such as cross‐over or cluster‐RCTs.

Dealing with missing data

Any further information required from the original author was requested by written correspondence by emailing the corresponding author. The evaluation of important numerical data, such as screened and randomised patients, was carefully performed. Attrition rates, such as dropouts, losses to follow‐up, and withdrawals, were investigated. Issues of missing data and imputation methods (e.g. last‐observation‐carried‐forward) were critically appraised (Higgins 2022).

Assessment of heterogeneity

Exploration into statistical heterogeneity was performed with potential sources identified; this included sub‐group analysis (as described below). We quantified statistical heterogeneity using the I² statistic (Higgins 2003). I² values of 25%, 50% and 75% indicated low, medium and high levels of heterogeneity, respectively. Analysis of heterogeneity was also undertaken using a Chi² test on N‐1 degrees of freedom, with an alpha of 0.05 used for statistical significance. When statistical heterogeneity was present, subgroup analysis was to be used to explore possible sources.

Assessment of reporting biases

We planned to use funnel plots to assess the potential existence of small study bias (Higgins 2022). Due to the small number of studies, funnel plots were not generated.

Data synthesis

Data was pooled using the random‐effects model, but we used fixed‐effect models to ensure the robustness of the model chosen and susceptibility to outliers.

Subgroup analysis and investigation of heterogeneity

Subgroup analysis was used to explore possible sources of heterogeneity. Potential subgroup analyses included:

• Donation after circulatory death (DCD) versus donation after brain‐stem death (DBD) versus live or mixed criteria kidneys

• Surgeon experience: one experienced surgeon performed or supervised all the operations in the study compared to many surgeons involved in the study

• Extended criteria donor (ECD) kidneys versus standard criteria kidneys

• High or unclear risk of bias versus low risk of bias

• Comparison of surgical technique: L‐P anastomosis via a transvesical approach compared to L‐G extravesical ureteroneocystostomy

Sensitivity analysis

We performed sensitivity analyses in order to explore the influence of the following factors on effect size.

• Repeating the analysis, taking account of the risk of bias, as specified

• Repeating the analysis, excluding any very long or large studies, to establish how much they dominate the results.

Summary of findings and assessment of the certainty of the evidence

The main results of the review are presented in a summary of findings table. This table presents key information concerning the quality of the evidence, the magnitude of the effects of the interventions examined, and the sum of the available data for the main outcomes (Schünemann 2022a). The summary of findings table also includes an overall grading of the evidence related to each main outcome using the Grades of Recommendation, Assessment, Development and Evaluation (GRADE) approach (GRADE 2008; GRADE 2011). The GRADE approach defines the certainty of a body of evidence as the extent to which one can be confident that an estimate of effect or association is close to the true quantity of specific interest. The certainty of a body of evidence involves consideration of within‐trial risk of bias (methodological quality), directness of evidence, heterogeneity, precision of effect estimates and risk of publication bias (Schünemann 2022b). The following outcomes are presented in the summary of findings table.

• MUC related to the transplant ureter (urine leak/obstruction) within three months of transplant

• Graft survival

• Patient survival

• Incidence of UTI

• Incidence of haematuria

• Other stent related complications: irritative symptoms, breakage, migration/malpositioning, encrustation, forgotten, expulsion.

Results

Description of studies

Results of the search

Twelve RCTs and quasi‐RCTs (1960 patients) were identified (Barbosa Neto 2018; Bassiri 1995; Benoit 1996; Charan Kumar 2016; Dominguez 2000; Guleria 1998; Kumar 1998; Majeed 2022; Osman 2005; Pleass 1995; SPLINT 2020; Zaki 2013). All but one (Barbosa Neto 2018) were published as full articles in English language journals; Barbosa Neto 2018 was only accessible as an abstract. Guleria 1998 was originally accessible as a full article, but since the 2024 update of this meta‐analysis, it is now only available as an abstract. This impacted specific sections of the risk of bias assessment. No dual publications or non‐English language studies were identified. Three of the 12 authors (Dominguez 2000; Osman 2005; Pleass 1995) answered enquiries about study design and results; whilst their assistance was invaluable, often original data was unavailable, and the basis for their response was personal memory. We did not pursue statistical attempts to identify publication bias.

A flow chart for the studies included in this review can be found in Figure 1.

1.

Flow diagram showing study selection

Included studies

In total, 12 RCTs and quasi‐RCTs (1960 patients) (Barbosa Neto 2018; Bassiri 1995; Benoit 1996; Charan Kumar 2016; Dominguez 2000; Guleria 1998; Kumar 1998; Majeed 2022; Osman 2005; Pleass 1995; SPLINT 2020; Zaki 2013) were included in this review. See Characteristics of included studies.

Insufficient information was provided for Barbosa Neto 2018 because only the abstract was available.

From the 12 studies, three were performed in India (Charan Kumar 2016; Guleria 1998; Kumar 1998), two in Pakistan (Majeed 2022; Zaki 2013), three in Europe (Benoit 1996; Pleass 1995; SPLINT 2020), one in Canada (Dominguez 2000), one in Iran (Bassiri 1995), one in Egypt (Osman 2005) and one in Brazil (Barbosa Neto 2018).

The inclusion and exclusion criteria of each study were difficult to assess. Only Dominguez 2000 reported patients assessed, enrolled or withdrawn prior to randomisation in keeping with modern CONSORT guidelines (Ioannidis 2004). Four studies (Bassiri 1995; Dominguez 2000; Majeed 2022; Osman 2005) specifically excluded kidneys and recipients with abnormal urinary tracts. One study included multi‐visceral recipients (Dominguez 2000), and in six studies (Charan Kumar 2016; Guleria 1998; Kumar 1998; Osman 2005; SPLINT 2020; Zaki 2013), the kidneys were only live donor‐derived. Paediatric recipients were specifically excluded by four studies (Barbosa Neto 2018; Osman 2005; Pleass 1995; SPLINT 2020). Zaki 2013 excluded patients with severe bladder abnormalities or those who underwent hyper‐acute rejection, whilst in other studies, the protocol was unclear. No study reported results on our specific exclusion criteria recipients.

All were two‐arm RCTs comparing the use of double‐J stents versus no double‐J stents in kidney transplant patients to determine whether prophylactic stenting of patients undergoing this procedure would achieve better outcomes or fewer MUCs.

Excluded studies

For full details for individual studies, see Characteristics of excluded studies.

We excluded 23 studies. One stated it was randomised but used a historical cohort for the control group (Moray 2005), and one had flaws in the randomisation process (Tavakoli 2007). Ten studies were excluded because they did not compare an intervention group (ureteric stent was inserted) with a control group (no ureteric stent inserted); the majority of these studies compared different types of stents and both groups received a stent (Battaglia 2005; DRKS00015038; ISRCTN89369862; Nadjafi‐Semnani 2020; NL‐OMON21650; Pansaksiri 2023; Smith 2012a; Taghizadeh‐Afshari 2014; TCTR20210204005; Wongtreeratanachai 2023). Eight studies were excluded because they compared early versus late stent removal as a primary outcome (Gunawansa 2011; Huang 2012; Indu 2012; Liu 2017; Parapiboon 2012; TrUST 2011; Verma 2002; Yari 2014). Two studies were excluded because they compared different surgical techniques for a kidney transplant (Dadkhah 2010; Zargar 2005), and one study compared the length of ureteric spatulation (Asadpour 2011).

Ongoing studies

One study (CTRI/2018/05/013647) is currently ongoing and will be assessed in a future update of this review (see Characteristics of ongoing studies).

Risk of bias in included studies

The following section aims to highlight some of the common biases found within the specified papers. Figure 2 summarizes each risk of bias item for each included study, and Figure 3 presents each risk of bias item as percentages across all included studies.

2.

Risk of bias summary: review authors' judgements about each risk of bias item for each included study.

3.

Risk of bias graph: review authors' judgements about each risk of bias item presented as percentages across all included studies.

Allocation

Five studies (Guleria 1998; Kumar 1998; Osman 2005; Pleass 1995; SPLINT 2020) detailed a robust method of randomisation which would be unaffected by physician pre‐conceptions, resulting in a low risk of bias. Majeed 2022 also demonstrated a reliable method of random sequence generation via a lottery method, leading to low risk, but did not report information on the concealment of allocations prior to assignment (unclear risk). Charan Kumar 2016 also used a robust method of randomisation using a computer‐generated Rand function on Microsoft Excel (low risk of bias). However, with respect to allocation concealment, due to the use of the Excel function, it was probable that investigators knew which group allocation was next, which suggests a lack of allocation concealment and a high risk of bias was deduced for this domain. Dominguez 2000 was designed with an intervention group randomised to receive stents universally and one arm receiving stents if the senior surgeon present deemed them necessary, a policy commonly termed "selective" stenting.

For two studies, the randomisation method was unclear, and the authors did not respond to attempts at clarification (Bassiri 1995; Benoit 1996); furthermore, from the information stated in Bassiri 1995, it cannot be determined whether the study was truly randomised or quasi‐randomised; it was therefore deduced that this study was at high risk of bias for both random sequence generation and allocation concealment. Similarly, with Zaki 2013, there was little to no information regarding the method of sequence generation and allocation concealment. It was difficult to understand whether this study was truly randomised or quasi‐randomised, and it was judged to be at high risk of bias. Barbosa Neto 2018 only had the abstract available with no information provided on the randomisation method or allocation bias and was judged to have unclear risks of bias for these two domains.

Blinding

Performance bias

Eleven studies (Barbosa Neto 2018; Bassiri 1995; Benoit 1996; Charan Kumar 2016; Dominguez 2000; Guleria 1998; Kumar 1998; Majeed 2022; Osman 2005; Pleass 1995; Zaki 2013) were deemed 'unclear' within this domain. There was little to no mention of whether the studies were blinded in relation to clinician and patient groups. Majeed 2022 stated that the study was not double‐blinded. Conversely, there was no report that the study was single‐blinded either, and the risk of bias was judged to be unclear. SPLINT 2020 was deemed to have a low risk of bias in this domain. The author concluded that blinding was not possible due to the use of externalised stenting; however, we feel this was unlikely to impact the outcome of MUCs requiring intervention after the stent was removed.

Detection bias

Six studies (Benoit 1996; Dominguez 2000; Kumar 1998; Majeed 2022; Osman 2005; SPLINT 2020) were judged to be at low risk of detection bias; although no blinding was mentioned, each study presented clear pre‐specified outcomes, definitions and protocol follow‐up. Five studies (Barbosa Neto 2018; Bassiri 1995; Guleria 1998; Pleass 1995; Zaki 2013) were judged to have an unclear risk of detection bias due to insufficient information. Charan Kumar 2016 was considered to be at high risk of detection bias. A clinician's awareness of which patients were in the stented and non‐stented groups could influence thresholds for investigation with regard to UTI symptomatology. Furthermore, with no strict pre‐specified definitions for UTI diagnosis, it was deemed that bias could have impacted the study's outcomes.

Incomplete outcome data

In nine studies (Benoit 1996; Dominguez 2000; Guleria 1998; Kumar 1998; Majeed 2022; Osman 2005; Pleass 1995; SPLINT 2020; Zaki 2013), the authors included all relevant information regarding pre‐determined outcomes. All patients were followed up within the correct time frame and there was no missing data; a low risk of attrition bias was therefore indicated.

Bassiri 1995 and Osman 2005 presented their results censored for either graft loss or patient death unrelated to urological complications or stents. During our meta‐analysis, these results were adjusted to include the patients as originally randomised. Pleass 1995 randomised patients into four groups: L‐G or L‐P with or without stent. These results were summated into "with" and "without stent" groups. Only Guleria 1998 detailed a loss to follow‐up before three months.

Benoit 1996, Guleria 1998 and Kumar 1998 stated that the operations reported were consecutive and detailed no exclusions. None of these authors responded to attempts to contact them, and the inclusion and exclusion criteria from their protocols could not be confirmed.

In two studies (Barbosa Neto 2018; Bassiri 1995), we could not judge the risk of bias in this domain due to lack of information. The former was only available as an abstract, and the latter included no data on the number of patients lost to follow‐up, unclear pre‐specified outcomes and P values as well as graft and survival rates were not stated. Charan Kumar 2016 excluded patients who experienced complications from the results; this was concluded to be a high risk of bias.

Selective reporting

Nine studies (Benoit 1996; Charan Kumar 2016; Dominguez 2000; Kumar 1998; Majeed 2022; Osman 2005; Pleass 1995; SPLINT 2020; Zaki 2013) reported their pre‐specified intended outcomes adequately in a thorough and unambiguous fashion.

Bassiri 1995 was determined to have a high risk of selection bias. Five patients were excluded from the study due to death or rejection; this was not included in the results section. In addition, no clear pre‐specified outcomes were noted, and those that were mentioned were not adequately described.

We were unable to assess the risk of selection bias for two studies (Barbosa Neto 2018; Guleria 1998); both studies were only available as abstracts. Barbosa Neto 2018 included incomplete data on their primary outcomes with no mention of any other secondary or unexpected adverse effects. Similarly, with Guleria 1998, there were no prespecified outcomes and no clear definition of what they regarded as a positive UTI diagnosis. With insufficient information, the judgement was unable to be permitted.

Other potential sources of bias

Two studies (Barbosa Neto 2018; Guleria 1998) were only available as abstracts with no protocol, no full text, and lacked any information required for a thorough risk of bias assessment, and were both judged to have a high risk of bias.

The lack of intention‐to‐treat (ITT) analysis was seen in two studies (Kumar 1998; Majeed 2022). In Kumar 1998, no information was presented on ITT, and there was a large disparity between the number of patients in each group (57 in the stented group and 43 in the non‐stented group). This suggests that several patients randomised to the non‐stented group actually received a stent at the discretion of the operating surgeon and were included in the stented group for the purposes of analysis, therefore giving rise to potential bias in favour of the non‐stented group. Majeed 2022 presented no information on their ITT status; thus, a high risk of bias was concluded.

Two studies (Bassiri 1995; Kumar 1998) mentioned the early removal of stents, and in both studies, two patients were involved. The reasoning behind the premature stent removal was due to frank haematuria and persistent UTIs, respectively. This may have consequences for the rate of MUCs, but as the ITT status is not clearly stated in either study, it cannot be concluded whether the patients remained within the stented group or were discontinued as a result of the event.

Zaki 2013 did not pre‐publish a protocol or register the study on a trials database; a high risk of bias was determined for this study. Similarly, in Bassiri 1995, there was no clear, pre‐specified definition used for UTI diagnosis and a high risk of bias was also concluded.

Osman 2005 and Pleass 1995 were judged to have unclear risks of bias due to insufficient information provided for ITT.

Four studies (Benoit 1996; Charan Kumar 2016; Dominguez 2000; SPLINT 2020) were judged to have a low risk of other biases.

In summary, the studies were of low or medium quality, and the study designs were heterogeneous with disparate donors, intervention periods, outcome assessments, and statistical analysis. However, common themes of randomisation and control were present in all studies, and the primary research question of each study followed the principle of this review. After consultation between all four authors, we included all the studies in our meta‐analysis.

Effects of interventions

See: Table 1

Urine leak and obstruction

The MUCs (leak and/or stenosis) incidence ranged between 0% and 8% in stented patients (median 1.0%) and between 0% and 24% (median 7.0 %) in the non‐stented patients (see Table 2: Incidence of major urological complications). There were fewer events in the stent group (Analysis 1.1.1 (11 studies, 1834 participants): RR 0.30, 95% CI 0.16 to 0.55; P < 0.0001; I² = 16%; NNT = 17). This treatment effect appeared uniform for both complications, with urine leak (Analysis 1.1.2 (11 studies, 1834 participants): RR 0.26, 95% CI 0.12 to 0.56; P = 0.0005; I² = 0%) and ureteric obstruction (Analysis 1.1.3 (10 studies, 1726 participants): RR 0.47, 95% CI 0.25 to 0.87; P = 0.02; I² = 0%) similarly reduced. Overall, this was judged to be moderate certainty evidence due to a notable high risk of bias in specific domains across the studies involved. However, the only study deemed low risk of bias across all domains (SPLINT 2020) confirmed that universal prophylactic stenting reduces MUCs (high certainty evidence) and is consistent with the overall results (Analysis 1.1).

1. Incidence of major urological complications.

Study	Events (stent)	Patients (stent)	Incidence (stent)	Events (no stent)	Patients (no stent)	Incidence (no stent)
Bassiri 1995	0	35	0%	3	37	8.1%
Benoit 1996	1	97	1.0%	10	97	10.3%
Charan Kumar 2016	0	36	0%	3	36	8.3%
Dominguez 2000	5	143	3.5%	9	137	6.6%
Guleria 1998	1	54	1.9%	3	54	5.6%
Kumar 1998	0	57	0%	3	43	7.0%
Majeed 2022	0	54	0%	2	54	3.7%
Osman 2005	2	50	4%	0	50	0%
Pleass 1995	0	150	0%	26	150	17.3%
SPLINT 2020	8	100	8.0%	24	100	24.0%
Zaki 2013	2	150	1.3%	4	150	2.7%
Total	19	926	median 1.0 (0 to 8.0)	87	908	median 7.0 (0 to 24.0)

1.1. Analysis.

Comparison 1: Stent versus no stent, Outcome 1: Urine leak and obstruction

Subgroup analyses

Duration of stenting

We investigated the effect of stent duration on the incidence of MUC ‐ categorised as short duration stents being in situ for ≤ 14 days and longer duration being > 14 days. Universal prophylactic ureteric stent insertion probably reduces the risk of MUC in the subgroup of studies with short‐duration stenting (Analysis 1.2.1 (2 studies, 480 participants): RR 0.39, 95% CI CI 0.21 to 0.72; P = 0.003; I² = 0%) and in studies where stenting was continued for > 14 days (Analysis 1.2.2 (8 studies, 124 participants): RR 0.22, 95% CI 0.08 to 0.61; P = 0.004; I² = 29%). There was no evidence to suggest a difference in treatment effect between short and long‐duration subgroups (P = 0.60).

1.2. Analysis.

Comparison 1: Stent versus no stent, Outcome 2: Subgroup analysis for major urological complications: duration of stenting

Surgeon's experience

We also investigated the influence of a surgeon's experience on MCU. In studies where only a single experienced surgeon performed or supervised all the operations, the incidence of MUCs in the control group was lower (median 6.3% versus 7.45%) (Analysis 1.3.1 same surgeon (4 studies, 380 participants): RR 0.39, 95% CI 0.08 to 1.86; P = 0.24; I² = 23%) (Analysis 1.3.2 many surgeons (6 studies, 1254 participants): RR 0.21, 95% CI 0.07 to 0.64; P = 0.006; I² = 43%) (see Table 3: Influence of surgeon number on incidence of major urological complications) and hence the benefit of stent placement was lower (NNT 30 versus 15).

1.3. Analysis.

Comparison 1: Stent versus no stent, Outcome 3: Subgroup analysis for major urological complications: surgeon's experience

2. Influence of surgeon number on incidence of major urological complications.

Study	Events (stent)	Patients (stent)	Incidence (stent)	Events (no stent)	Patients (no stent)	Incidence (no stent)
Bassiri 1995	0	35	0%	3	37	8.1%
Guleria 1998	1	54	1.9%	3	54	5.6%
Kumar 1998	0	57	0%	3	43	7.0%
Osman 2005	2	50	4%	0	50	0%
Same surgeon (4 studies, 380 patients)	3	196	median 0.95 (0 to 4.0)	9	184	median 6.3 (0 to 8.1)
Benoit 1996	1	97	1.0%	10	97	10.3%
Charan Kumar 2016	0	36	0%	3	36	8.3%
Dominguez 2000	5	143	3.5%	9	137	6.6%
Majeed 2022	0	54	0%	2	54	3.7%
Pleass 1995	0	150	0%	26	150	17.3%
Zaki 2013	2	150	1.3%	4	150	2.7%
Many surgeons (6 studies, 1254 patients)	8	630	median 0.5 (0 to 3.5)	54	624	median 7.45 (2.7 to 17.3)

Of the two studies in which both L‐P and L‐G techniques were utilised, only Pleass 1995 reported results on L‐P procedures separately and showed a greater incidence of MUCs in the unstented L‐P group and a concomitantly larger risk reduction with the use of stents. The influence of the donor organ type (cadaveric, live, multiorgan) or stent type could not be judged to have an effect due to the small number of studies. Similarly, we could not identify a correlation between the length of stent placement and the incidence of MUCs.

In Dominguez 2000 (stenting versus selective stenting), six (4.4%) patients in the control group received a prophylactic stent. Despite this, there were more MUCs in the control group than in the stent group. Three studies specifically reported better graft function or fewer MUCs whilst the stent was in situ. Bassiri 1995 reported no MUCs in the first two weeks post‐transplant in the stented group versus two in the non‐stented group. Benoit 1996 showed a noteworthy difference in kidney function early post‐transplant (mean serum creatinine (SCr) at one week: 302 µmol/L versus 388 µmol/L). Dominguez 2000 reported no MUCs within 20 days in the group that had been stented, whilst all the patients with MUCs in the non‐stented group presented within 13 days. In SPLINT 2020, 24 patients had MUCs: 12/100 (12%) due to urinary leakage and 12/100 (12%) due to hydronephrosis. However, from these complications, 10/100 (10%) needed surgical intervention (as opposed to percutaneous nephrostomy or resolving without intervention). In the stented group, 8/100 (8%) of patients suffered from MUCs, all of which were due to ureteric obstruction. From this group, only two patients warranted surgical re‐intervention; the remaining eight patients did not require any additional intervention.

Patient and graft survival

No studies directly attributed patient death to the use of ureteric stents. Benoit 1996 reported graft loss secondary to the use of ureteric stents: two kidneys had to be removed after stent encrustation with corynebacterium could not be eradicated with antibiotics. Charan Kumar 2016 excluded four patients; one in the stented group died from pseudomonas sepsis on the 7th post‐operative day; the infection source was proved to be from an internal jugular vein catheter, and the graft function was normal at the time of death. Similarly, SPLINT 2020 reported two deaths in the stented group and one death in the non‐stented group, all of which were not stent‐related. The former was due to respiratory insufficiency caused by Guillain‐Barre syndrome and cardiac reasons, respectively, and the latter was due to non‐Hodgkin lymphoma.

(See Table 4: graft loss and patient death).

3. Graft loss and patient death.

Study	Follow‐up	Stent‐related graft loss	Stent‐related death	Overall death	Overall graft loss
Bassiri 1995	2 to 10 months	0	0	Total of 5 patients either lost their graft or died (6.5%)	‐
Benoit 1996	Up to 3 years	2	0	7.8%	Not reported
Charan Kumar 2016	6 months	0	0	2.7%	2.7%
Dominguez 2000	3 months	0	0	Not reported	Not reported
Guleria 1998	6 months	0	0	0	1.9%
Kumar 1998	16 to 32 months	0	0	1‐year survival (93%)	1‐year survival (89%)
Majeed 2022	1 month	0	Not reported	Not reported	Not reported
Osman 2005	7 to 16 months	0	0	0.8%	0.8%
Pleass 1995	3 months	0	0	Not reported	Not reported
SPLINT 2020	12 months	0	0	3.0%	Not reported
Zaki 2013	1 to 4 years	Not reported	Not reported	Not reported	Not reported

Urinary tract infection

There was considerable heterogeneity in definitions, reported morbidity and relative incidence of UTI. Meta‐analysis identified that it is uncertain whether stenting has an impact on developing UTI (Analysis 1.4 (10 studies, 1726 participants): RR 1.32, 95% CI 0.97 to 1.80; P = 0.07) and does show statistical heterogeneity (Chi² = 22.50, P = 0.007, I² = 60%). This overall result was judged to be very low certainty evidence due to the risk of bias, imprecision, and heterogeneity, as well as the aforementioned inconsistencies in UTI definitions across the studies. This statistic was independent of the diagnostic criteria (Analysis 1.5), with an equivalent RR reported between studies diagnosing infection on the basis of culture alone (Analysis 1.5.1 (4 studies. 602 participants): RR 1.23, 95% CI 0.73 to 2.06, P = 0.43; I² = 83%) and studies requiring clinical symptoms for confirmation of infection (Analysis 1.5.2(4 studies, 752 participants): RR 1.21, 95% CI 0.82 to 1.78; P = 0.33; I² = 0%).

1.4. Analysis.

Comparison 1: Stent versus no stent, Outcome 4: UTI

1.5. Analysis.

Comparison 1: Stent versus no stent, Outcome 5: UTI: diagnostic criteria

If there is a short duration of stent insertion, the risk of UTI is not increased (SPLINT 2020: stent removed at nine days). This study has a low risk of bias with a clear, unambiguous and reasonable definition for diagnosing UTI which is clinically relevant. Subgroup analysis also suggested that there is no impact on UTI risk when the prophylactic antibiotic regime co‐trimoxazole is used (Analysis 1.6). Studies detailing prophylaxis (Bassiri 1995 excluded) with long‐term co‐trimoxazole 480 mg/day (or 960 mg alternate days) had an equivalent RR for infection between stented and non‐stented patients (Analysis 1.6.1 (3 studies, 594 participants): RR 0.97, 95% CI 0.71 to 1.33; P = 0.85; I² = 0%) compared with other regimes (Analysis 1.6.2 (5 studies, 860 participants): RR 1.71, 95% CI 1.40 to 2.09; P < 0.00001; I² = 0%). The co‐trimoxazole regime detailed by Dominguez 2000 included only three doses of co‐trimoxazole 480 mg/week.

1.6. Analysis.

Comparison 1: Stent versus no stent, Outcome 6: UTI: antibiotic regimen

Haematuria

Graft implantation requires bladder incision, and there will always be a level of haematuria after kidney transplantation. As a symptom or clinical finding, haematuria was sporadically reported by investigators, and the definitions varied widely (see Table 5: Incidence of haematuria). Three studies reported cases of ureteric clot retention (Benoit 1996; Dominguez 2000; SPLINT 2020), and only four studies gave specific definitions for haematuria (Bassiri 1995; Osman 2005; Pleass 1995; SPLINT 2020). Zaki 2013 only reported the incidence of haematuria if it lead to urinary retention and, therefore, intervention. Of the four studies that gave figures for haematuria, two studies reported more morbidity in the stented group, and one study reported more in the non‐stented group. There was no evidence that the presence of a stent resulted in recurrent or severe haematuria Analysis 1.7 (8 studies, 1546 participants): RR 1.09, 95% CI 0.59 to 2.00; P = 0.79; I² = 33%). With inconsistencies in definitions of pathological haematuria compared to 'expected haematuria' post‐kidney transplant, this was judged to be low certainty evidence.

4. Incidence of haematuria.

Study	Stent	No stent
Bassiri 1995	5.7%	0%
Benoit 1996	Not reported	1 ureter clot retention (1.0%)
Charan Kumar 2016	Not reported	Not reported
Dominguez 2000	Not reported	1 ureter clot retention (0.7%)
Guleria 1998	Not reported	Not reported
Kumar 1998	0%	0%
Majeed 2022	Not reported	Not reported
Osman 2005	6.0%	2.0%
Pleass 1995	6.0%	10.0%
SPLINT 2020	76%	1 ureter clot retention (50%)
Zaki 2013	0.7%	1.3%

1.7. Analysis.

Comparison 1: Stent versus no stent, Outcome 7: Haematuria

Other complications

See Table 6: Other stent‐related complications.

5. Other stent‐related complications.

Study	Irritative symptoms	Breakage	Migration/malpositioning	Encrustation	Forgotten	Expulsion
Bassiri 1995	Not reported	Not reported	Not reported	5.7%	Not reported	0
Benoit 1996	Not reported	2.1%	1.0%	2.1%	Not reported	1.0%
Charan Kumar 2016	Not reported	Not reported	Not reported	Not reported	Not reported	Not reported
Dominguez 2000	0%	0%	0 %	0%	Not reported	0%
Guleria 1998	5.6%	0%	7.4%	0%	Not reported	7.4%
Kumar 1998	5.3%	0%	0%	0%	7.0%	0
Majeed 2022	Not reported	Not reported	Not reported	Not reported	Not reported	Not reported
Osman 2005	Not reported	0%	4.0%	0%	0	0
Pleass 1995	Not reported	0%	"+"	"++"	Not reported	> 1 patient
SPLINT 2020	Not reported	Not reported	Not reported	Not reported	Not reported	Not reported
Zaki 2013	1.33%	Not reported	0.7%	Not reported	Not reported	Not reported

The most significant complications reported were two graft losses in Benoit 1996. Only two stent breakages were reported, both in patients receiving simultaneous pancreas‐kidney transplants with bladder exocrine drainage. Encrustation appeared to be a considerable problem for stents left for longer periods (Bassiri 1995; Pleass 1995), although this statistic was not reported in the original paper by Pleass 1995. The highest rate of stent migration and expulsion was reported by Guleria 1998 who used the longest (24 cm) stent. Cases of "forgotten" stents were reported in Kumar 1998, but none of these cases were associated with excess morbidity. Stents appeared well tolerated whilst in situ, with only three studies reporting an excess of irritative symptoms and pain not associated with infection (Guleria 1998; Kumar 1998; Zaki 2013). No studies reported complications from routine removal or secondary obstruction from encrustation.

In summary, the maximum reported non‐infectious complications were irritative symptoms (5.6%) (Guleria 1998), breakage (2.0%) (Benoit 1996), migration/malposition/expulsion (7.4%) (Guleria 1998), encrustation/urolithiasis (5.7%) (Bassiri 1995) and "forgotten" stents (7%) (Kumar 1998).

Discussion

Summary of main results

MUCs require interventions varying in severity from a radiological nephrostomy to surgical urinary diversion. Consequently, any intervention which can safely and cost‐effectively lower their incidence is to be welcomed. Our analysis demonstrates that universal prophylactic ureteric stenting probably reduces the incidence of MUCs (RR 0.30, 95% CI 0.16 to 0.55; P < 0.0001; I² = 16%). Overall, the evidence was moderate certainty due to the risk of bias. However, the single study deemed low risk of bias across all domains (SPLINT 2020) confirmed that universal prophylactic ureteric stenting reduced the incidence of MUCs and was consistent with the main meta‐analysis results.

Universal prophylactic ureteric stent insertion probably reduces the risk of MUCs in the subgroup of studies with short duration (≤ 14 days) of stenting (RR 0.39, 95% CI CI 0.21 to 0.72; P = 0.003; I² = 0%) and in studies where stenting was continued for > 14 days (RR 0.22, 95% CI 0.08 to 0.61; P = 0.004; I² = 29%). There was no evidence of subgroup differences (P = 0.60), suggesting that a longer duration of stenting may not result in greater benefits in terms of the incidence of MUCs. However, further high‐quality studies are required to address this question and define the optimal duration of ureteric stenting.

While we performed subgroup analyses based on stent duration, this systematic review did not include studies directly comparing short versus long duration of stenting. Our group has published a review that included studies directly comparing early (≤ 14 days) and late (> 14 days) stent removal and concluded that there may be a benefit from removing the stent early with respect to the incidence of UTIs and with no increase in the incidence of MUC's (Thompson 2018). Further high‐quality studies must be done in order to achieve a definitive conclusion on this matter, as current practice ranges from stitching the ureteric stent to the catheter (and therefore removal before one week) to ureteric stent removal several weeks later on elective theatre lists.

We could not identify a particular stent design associated with a better outcome as a wide variety of stent designs, calibres and lengths were used. Non‐infectious adverse events appeared more common in studies using longer stents (Guleria 1998; Osman 2005) and/or longer treatment periods (Bassiri 1995; Pleass 1995), although there was no evidence that haematuria was more common. These idiosyncratic stent‐related complications were mostly managed by endoscopic removal of the stent ‐ a minimally invasive procedure ‐ which was unavoidable after initial stent placement and has been successfully combined with other necessary interventions for transplant recipients (e.g. peritoneal and haemodialysis catheter removal). Irritative symptoms and stent‐related pain were much less frequent than would be expected from studies examining the use of stents in native ureters after general urological procedures where the incidence may be as high as 80% (Joshi 2003). Kumar 2004 suggested that the combination of a denervated kidney and the high anterior placement of the stent reduces the combination of vesicoureteric reflux pain and trigonal irritation. However, none of the studies specifically used a validated questionnaire to quantify the urinary symptoms or bother associated with either stent usage or removal, and this may well be an underestimate of the morbidity burden.

Two grafts were lost as a result of stent‐related infectious complications. However, the pooled results indicated that it is uncertain whether stenting has an impact on developing UTI (RR 1.32, 95% CI 0.97 to 1.80; P = 0.007; I² = 60%; very low certainty evidence due to imprecision, risk of bias, heterogeneity and inconsistent definitions). Subgroup analysis demonstrated that UTI risk is not increased if short‐duration stenting is used (nine days) and that there is no impact on UTI risk when the prophylactic antibiotic regime co‐trimoxazole 480 mg/day is used. Co‐trimoxazole, at a dose of 480 mg/day or 960 mg every other day, is standard therapy in most units and recommended in published guidelines for all kidney transplant recipients as prophylaxis against Pneumocystis carinii pneumonia (EBPG 2002). It should be emphasised that these subgroup analyses, in common with all the analyses, are based on a small number of studies and are open to reporting errors.

Only one study reported a cost‐benefit analysis, and although the morbidity associated with stents appears minimal and the therapeutic benefit sizeable, there remain unanswered questions regarding economic and QoL issues. In this respect, a study of selective versus universal stenting, utilising a stent‐specific QoL instrument, would not only provide the opportunity for a more realistic cost‐benefit analysis of universal prophylactic stenting but also demonstrate whether surgeons can identify intra‐operatively urinary tracts that need to be stented. Such a study would also need to stratify surgeons by experience to have significant worldwide implications for practice.

Overall completeness and applicability of evidence

The 12 studies included in this review took place in a variety of locations (India, Pakistan, Europe, Canada, Iran and Brazil), illustrating the involvement of a multitude of surgeons, patients and experts. The majority of the studies included took place over a decade ago, which arguably gives rise to the idea that the results are somewhat outdated, but with the same surgical techniques, management protocols, and complications seen today, the results can still be utilised. Overall, we feel the results of this review are applicable to many different transplant centres and settings.

All 12 studies recorded the incidence of MUCs in both stented and non‐stented groups, and data was provided with the exception of Barbosa Neto 2018, which was only available as an abstract. With respect to other secondary outcomes, patient survival was reported in six studies and graft survival was reported in four studies. Data was available on UTI incidence in 10 studies, whilst haematuria rates were recorded in eight studies. It is noteworthy that definitions for diagnosing UTIs, as well as thresholds for recording haematuria, were inconsistent across the studies. There was limited data on other stent‐related complications (e.g. migration/malposition, breakage, irritation, encrustation) and not one study reported on all complications; however, collectively, four studies reported irritative symptoms, six reported stent breakage, six reported malpositioning, six reported encrustation and six reported expulsion. Of the 12 study authors, three (Dominguez 2000; Osman 2005; Pleass 1995) answered enquiries about their study design and results; however, the original data was unavailable, and responses were recalled from personal memory; these were not included to avoid publication bias.

We have reported the number of stents needed to prevent one MUC from occurring in our results. This number was generated from the incidence of MUCs across the 12 included studies. We feel this can be applied to transplant centres universally, but factors such as surgeon experience, method of surgical technique and type of stent must also be considered. Within the subgroup analysis, we also reported the NNT with respect to MUC incidence when one experienced surgeon performs versus the inclusion of many surgeons involved; the application of this information is specific to the transplant centre with the surgical team and expertise that are at their disposal.

Quality of the evidence

A summary of identified biases can be found in the Risk of bias in included studies section.

SPLINT 2020 was deemed low risk of bias across all domains. The remaining 11 studies were of low or medium quality, with a high or unclear risk of bias in at least one domain. The study designs were heterogeneous, with discordant donors, intervention periods, outcome assessments, and statistical analysis; however, common themes of randomisation and control were present in all studies. The older studies (those published prior to 2000) had short manuscripts, making it difficult to assess the risk of bias.

The primary outcome in 11 studies was the incidence of MUCs in both stented and non‐stented patients following a kidney transplant. SPLINT 2020 specifically assessed MUCs requiring percutaneous nephrostomy with or without further intervention. Indications for this include urinary leak or a rise in SCr combined with hydronephrosis. Barbosa Neto 2018 attempted to measure the incidence of bacteriuria and/or UTI as its primary outcome; as mentioned, this study was only available in abstract form and no data was reported with respect to this outcome.

Our primary outcome of incidence of MUCs was measured within three months post‐transplant; therefore, the majority of patients would not be in hospital throughout this time period. This could have led to difficulty in ensuring complete follow‐up of the patients; however, nine of the studies included all the relevant information regarding pre‐determined outcomes, and all patients were followed up. In the majority of studies, the primary outcome was reported in a standardised fashion; studies simply reported raw data with the incidence of MUCs recorded for the stented and non‐stented groups. Only Barbosa Neto 2018 did not, as it was only available as an abstract. This resulted in high certainty evidence for this outcome.

No study reported all of our secondary outcomes. The incidence of UTI was the second most reported outcome in 10 studies. Furthermore, the studies had different definitions for what they deemed a positive UTI and thresholds for reporting haematuria. This meant that the quality of evidence for outcomes other than the incidence of MUCs was lower (see Table 1).

Potential biases in the review process

There was an attempt to minimise biases at each stage of our review. The Cochrane Kidney and Transplant Specialised Register was used to perform the search for the included studies, and it was done in a systematic and regulated fashion. Two independent authors screened the identified studies prior to inclusion in the review. A standardised data extraction form was used to collect data from included studies. This was done independently by two authors, and any discrepancies were resolved. Subgroup analysis was only performed if prespecified in our protocol to limit bias from multiple comparisons. There is, however, always a possibility that we failed to identify some relevant studies.

Agreements and disagreements with other studies or reviews

Comparing this meta‐analysis with other reviews, Mangus 2004 reported a similar treatment effect. This study included only five RCTs (796 patients). However, there is a significant "caveat" to these conclusions. RCTs with unblinded treatment allocation have been acknowledged to overestimate the beneficial effects of medical interventions by up to 40% (Schulz 1995). Such an overestimate would comprehensively negate the treatment effect described here. It was slightly surprising, therefore, that despite nine of the 12 studies showing a reduction in the MUC incidence, only three studies recommended universal prophylactic stenting.

One explanation for this may be an "experience" effect. The four studies with a single senior surgeon performing or supervising all the operations had a lower complication rate in the control group when compared with studies where more than one surgical team performed the operations. This has been suggested previously and may explain the conclusions of senior study investigators, cognisant of their considerable personal experience, extolling a policy of selective stenting (French 2001).

Similar conclusions can be drawn from this update compared to previous versions. It is still consistent that routine intraoperative prophylactic stenting in kidney transplant patients decreases the incidence of MUCs, and although stents do pose a risk of specific complications, surgeons may opt for a selective stenting approach to minimise stent‐related morbidity.

A second team from our group has published a review looking at early (≤ 14 days) and late (> 14 days) stent removal and concluded that there may be a benefit of removing the stent early on the incidence of UTIs (Thompson 2018) with no increase in the incidence of MUCs. Consequently, in this most recent review, we have removed the parameters of stent duration. However, the two reviews should be considered independently when determining policy.

Authors' conclusions

Implications for practice.

Routine prophylactic stenting reduces the incidence of MUCs in patients undergoing kidney transplantation. These benefits are seen even with a short duration (≤ 14 days) of stenting. It is uncertain whether stenting has an impact on developing UTIs. Furthermore, if there is a short duration of stent insertion time, UTI risk is not increased. There is also no impact of using prophylactic co‐trimoxazole at a dose of 480 mg/day to reduce the risk of UTIs associated with stent placement.

Implications for research.

The optimal stent calibre, length, design, and duration remain to be determined, and further studies could be instituted to address these issues. Well‐designed studies of stenting versus selective stenting, with appropriate patient selection protocols, randomisation, QoL questionnaires, cost‐benefit analyses and surgeon stratification, would answer the more clinically important question of whether it is possible and desirable to identify the appropriate patients to stent at the time of graft implantation. Although we included subgroup analyses based on stent duration, we did not include studies directly comparing stent durations; the latter is the topic of another Cochrane review (Thompson 2018).

What's new

Date	Event	Description
9 July 2024	New search has been performed	New studies included
9 July 2024	New citation required but conclusions have not changed	New version

History

Protocol first published: Issue 3, 2004
Review first published: Issue 4, 2005

Date	Event	Description
27 March 2013	New search has been performed	Repeat literature search performed, 14 abstracts evaluated. All excluded, no further changes to review.
8 January 2013	Amended	Search strategies updated
19 January 2010	Amended	Contact details updated.
8 May 2008	New search has been performed	Six potential studies identified and excluded
8 May 2008	Amended	Converted to new review format.
24 August 2005	New citation required and conclusions have changed	Substantive amendment

Appendices

Appendix 1. Electronic search strategies

Database searched	Search terms
CENTRAL	MeSH descriptor: [Kidney Transplantation] this term only kidney transplant*:ti,ab,kw (Word variations have been searched) renal transplant*:ti,ab,kw (Word variations have been searched) 1 or 2 or 3 MeSH descriptor: [Stents] explode all trees stent*:ti,ab,kw in Trials (Word variations have been searched) 5 or 6 4 and 7
MEDLINE	Kidney Transplantation/ exp Stents/ stent$.tw. or/2‐3 and/1,4
EMBASE	exp kidney transplantation/ exp stent/ exp urologic stent/ stent$.tw. or/2‐4 and/1,5

Appendix 2. Risk of bias assessment tool

Potential source of bias	Assessment criteria
Random sequence generation Selection bias (biased allocation to interventions) due to inadequate generation of a randomised sequence	Low risk of bias: Random number table; computer random number generator; coin tossing; shuffling cards or envelopes; throwing dice; drawing of lots; minimization (minimization may be implemented without a random element, and this is considered to be equivalent to being random).
	High risk of bias: Sequence generated by odd or even date of birth; date (or day) of admission; sequence generated by hospital or clinic record number; allocation by judgement of the clinician; by preference of the participant; based on the results of a laboratory test or a series of tests; by availability of the intervention.
	Unclear: Insufficient information about the sequence generation process to permit judgement.
Allocation concealment Selection bias (biased allocation to interventions) due to inadequate concealment of allocations prior to assignment	Low risk of bias: Randomisation method described that would not allow investigator/participant to know or influence intervention group before eligible participant entered in the study (e.g. central allocation, including telephone, web‐based, and pharmacy‐controlled, randomisation; sequentially numbered drug containers of identical appearance; sequentially numbered, opaque, sealed envelopes).
	High risk of bias: Using an open random allocation schedule (e.g. a list of random numbers); assignment envelopes were used without appropriate safeguards (e.g. if envelopes were unsealed or non‐opaque or not sequentially numbered); alternation or rotation; date of birth; case record number; any other explicitly unconcealed procedure.
	Unclear: Randomisation stated but no information on method used is available.
Blinding of participants and personnel Performance bias due to knowledge of the allocated interventions by participants and personnel during the study	Low risk of bias: No blinding or incomplete blinding, but the review authors judge that the outcome is not likely to be influenced by lack of blinding; blinding of participants and key study personnel ensured, and unlikely that the blinding could have been broken.
	High risk of bias: No blinding or incomplete blinding, and the outcome is likely to be influenced by lack of blinding; blinding of key study participants and personnel attempted, but likely that the blinding could have been broken, and the outcome is likely to be influenced by lack of blinding.
	Unclear: Insufficient information to permit judgement
Blinding of outcome assessment Detection bias due to knowledge of the allocated interventions by outcome assessors.	Low risk of bias: No blinding of outcome assessment, but the review authors judge that the outcome measurement is not likely to be influenced by lack of blinding; blinding of outcome assessment ensured, and unlikely that the blinding could have been broken.
	High risk of bias: No blinding of outcome assessment, and the outcome measurement is likely to be influenced by lack of blinding; blinding of outcome assessment, but likely that the blinding could have been broken, and the outcome measurement is likely to be influenced by lack of blinding.
	Unclear: Insufficient information to permit judgement.
Incomplete outcome data Attrition bias due to amount, nature or handling of incomplete outcome data.	Low risk of bias: No missing outcome data; reasons for missing outcome data unlikely to be related to true outcome (for survival data, censoring unlikely to be introducing bias); missing outcome data balanced in numbers across intervention groups, with similar reasons for missing data across groups; for dichotomous outcome data, the proportion of missing outcomes compared with observed event risk not enough to have a clinically relevant impact on the intervention effect estimate; for continuous outcome data, plausible effect size (difference in means or standardized difference in means) among missing outcomes not enough to have a clinically relevant impact on observed effect size; missing data have been imputed using appropriate methods.
	High risk of bias: Reason for missing outcome data likely to be related to true outcome, with either imbalance in numbers or reasons for missing data across intervention groups; for dichotomous outcome data, the proportion of missing outcomes compared with observed event risk enough to induce clinically relevant bias in intervention effect estimate; for continuous outcome data, plausible effect size (difference in means or standardized difference in means) among missing outcomes enough to induce clinically relevant bias in observed effect size; ‘as‐treated’ analysis done with substantial departure of the intervention received from that assigned at randomisation; potentially inappropriate application of simple imputation.
	Unclear: Insufficient information to permit judgement
Selective reporting Reporting bias due to selective outcome reporting	Low risk of bias: The study protocol is available and all of the study’s pre‐specified (primary and secondary) outcomes that are of interest in the review have been reported in the pre‐specified way; the study protocol is not available but it is clear that the published reports include all expected outcomes, including those that were pre‐specified (convincing text of this nature may be uncommon).
	High risk of bias: Not all of the study’s pre‐specified primary outcomes have been reported; one or more primary outcomes is reported using measurements, analysis methods or subsets of the data (e.g. subscales) that were not pre‐specified; one or more reported primary outcomes were not pre‐specified (unless clear justification for their reporting is provided, such as an unexpected adverse effect); one or more outcomes of interest in the review are reported incompletely so that they cannot be entered in a meta‐analysis; the study report fails to include results for a key outcome that would be expected to have been reported for such a study.
	Unclear: Insufficient information to permit judgement
Other bias Bias due to problems not covered elsewhere in the table	Low risk of bias: The study appears to be free of other sources of bias.
	High risk of bias: Had a potential source of bias related to the specific study design used; stopped early due to some data‐dependent process (including a formal‐stopping rule); had extreme baseline imbalance; has been claimed to have been fraudulent; had some other problem.
	Unclear: Insufficient information to assess whether an important risk of bias exists; insufficient rationale or evidence that an identified problem will introduce bias.

Data and analyses

Comparison 1. Stent versus no stent.

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1.1 Urine leak and obstruction	11		Risk Ratio (M‐H, Random, 95% CI)	Subtotals only
1.1.1 Combined: urine leak and obstruction	11	1834	Risk Ratio (M‐H, Random, 95% CI)	0.30 [0.16, 0.55]
1.1.2 Urine leak	11	1834	Risk Ratio (M‐H, Random, 95% CI)	0.26 [0.12, 0.56]
1.1.3 Ureteric obstruction	10	1726	Risk Ratio (M‐H, Random, 95% CI)	0.47 [0.25, 0.87]
1.2 Subgroup analysis for major urological complications: duration of stenting	11	1834	Risk Ratio (M‐H, Random, 95% CI)	0.30 [0.16, 0.55]
1.2.1 Stent duration ≤ 14 days	2	480	Risk Ratio (M‐H, Random, 95% CI)	0.39 [0.21, 0.72]
1.2.2 Stent duration > 14 days	8	1246	Risk Ratio (M‐H, Random, 95% CI)	0.22 [0.08, 0.61]
1.2.3 Stent duration not specified	1	108	Risk Ratio (M‐H, Random, 95% CI)	0.20 [0.01, 4.07]
1.3 Subgroup analysis for major urological complications: surgeon's experience	10		Risk Ratio (M‐H, Random, 95% CI)	Subtotals only
1.3.1 Same surgeon	4	380	Risk Ratio (M‐H, Random, 95% CI)	0.39 [0.08, 1.86]
1.3.2 Many surgeons	6	1254	Risk Ratio (M‐H, Random, 95% CI)	0.21 [0.07, 0.64]
1.4 UTI	10	1726	Risk Ratio (M‐H, Random, 95% CI)	1.32 [0.97, 1.80]
1.5 UTI: diagnostic criteria	8		Risk Ratio (M‐H, Random, 95% CI)	Subtotals only
1.5.1 Culture only	4	602	Risk Ratio (M‐H, Random, 95% CI)	1.23 [0.73, 2.06]
1.5.2 Culture plus symptoms/signs	4	752	Risk Ratio (M‐H, Random, 95% CI)	1.21 [0.82, 1.78]
1.6 UTI: antibiotic regimen	8		Risk Ratio (M‐H, Random, 95% CI)	Subtotals only
1.6.1 Co‐trimoxazole: 480 mg once/day (960 mg on alternate days)	3	594	Risk Ratio (M‐H, Random, 95% CI)	0.97 [0.71, 1.33]
1.6.2 Other regimen	5	860	Risk Ratio (M‐H, Random, 95% CI)	1.71 [1.40, 2.09]
1.7 Haematuria	8	1546	Risk Ratio (M‐H, Random, 95% CI)	1.09 [0.59, 2.00]

Characteristics of studies

Characteristics of included studies [ordered by study ID]

Barbosa Neto 2018.

Study characteristics
Methods	Study design Parallel RCT Setting: single centre Country: Brazil Duration of study: July 2015 to April 2016 Follow‐up: 3 months after procedure and 1 month after stent removal
Participants	Study characteristics Inclusion criteria: kidney transplant recipients Exclusion criteria: paediatric patients, double transplant (liver‐kidney or pancreas‐kidney) and patients with bladder augmentation surgeries Baseline characteristics Number: intervention group (65); control group (61) Mean age ± SD (years): not reported Sex (M/F): no reported
Interventions	Intervention group Stent type: 2J Stent calibre: not reported Stent length: not reported Stent duration (mean time of removal): 52 days Antibiotic regimen: not reported Anastomosis: not reported Surgeon: not reported Control group No ureteric stenting but otherwise treated identically to the stent group
Outcomes	Reported outcomes Incidence of bacteriuria and/or UTI
Notes	Additional information Funding: not reported Abstract‐only publication
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Only an abstract was available, no details on the randomisation process were given
Allocation concealment (selection bias)	Unclear risk	Only an abstract was available, no details on allocation concelament were given
Blinding of participants and personnel (performance bias)	Unclear risk	Only an abstract was available, and no information on if there was blinding or not. Additional urine cultures sent where UTI suspected would cause high risk of reporting bias if personnel not blinded
Blinding of outcome assessment (detection bias)	Unclear risk	Only an abstract was available, no details on blinding of outcome were given
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	No dichotomous data given in the abstract on the number of patients who suffered UTI, only stated as ‘no difference between groups’
Selective reporting (reporting bias)	Unclear risk	Incomplete data on their primary outcome in the abstract, no mention of any other secondary or unexpected adverse effects
Other bias	High risk	Available as abstract only with no protocol, no full text, and lack of any information required for a thorough risk of bias assessment

Bassiri 1995.

Study characteristics
Methods	Study design RCT/ quasi‐RCT Setting: single centre Country: Iran Duration of study: not reported Follow‐up: 2 to 10 months
Participants	Study characteristics Inclusion criteria: kidney transplant recipients Exclusion criteria: bladder problems; previous pelvic operation Baseline characteristics Number: intervention group (35); control group (37) Mean age ± SD (years): not reported Sex (M/F): not reported
Interventions	Intervention group Stent type: double J Stent calibre: not reported Stent length: 16 cm Stent duration: 6 to 8 weeks Antibiotic regimen: not reported Anastomosis: L‐G Surgeon: same team Control group No ureteric stenting but otherwise treated identically to the stent group
Outcomes	Reported outcomes MUC Haematuria: unclear (no definitions given ‐ "frank haematuria") Graft loss Death Encrustation Expulsion
Notes	Additional information Funding: not reported Deaths and rejection excluded Donor source: not reported
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	High risk	The author did not report the method of sequence generation, and it is unclear if this was truly randomised or quasi‐randomised
Allocation concealment (selection bias)	High risk	The author did not report any information on allocation concealment or the randomisation process and it is unclear if this was truly randomised or quasi‐randomised
Blinding of participants and personnel (performance bias)	Unclear risk	No mention of blinding, unable to report this domain
Blinding of outcome assessment (detection bias)	Unclear risk	No mention of blinding and if this has an impact on the outcome of the paper
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	No information on the number of patients lost to follow‐up. Little information regarding pre‐specified outcomes so it was therefore difficult to judge. P values were not stated as well as graft and survival rate
Selective reporting (reporting bias)	High risk	Five Patients were excluded from the trial due to death or rejection—this was not included in the results section and should have been. There were no clear pre‐specified outcomes, and those that were mentioned were not commented on—the author could conceivably record any complications they deem acceptable.
Other bias	High risk	There is no clear, pre‐specified definition used for UTI diagnosis

Benoit 1996.

Study characteristics
Methods	Study design RCT/quasi‐RCT Setting: single centre Country: France Duration of study: 3 July 1991 to 26 August 1994 Follow‐up: up to 3 years
Participants	Study characteristics Inclusion criteria: 194 consecutive cadaveric, live, kidney alone, kidney‐liver, kidney‐pancreas Exclusion criteria: none Baseline characteristics Number: intervention group (97); control group (97) Mean age ± SD (years): not reported Sex (M/F): not reported
Interventions	Intervention group Stent type: double J Stent calibre: 7 Fr Stent length: 16 cm Stent duration: 1 month Antibiotic regimen Prophylactic antibiotics for 48 hours followed by co‐trimoxazole Co‐trimoxazole 480 mg/day Anastomosis L‐G: extravesical ureteroneocystostomy in 180 cases (when bladder permitted) L‐P: anastomosis via a transvesical approach in 14 cases (if detrusor was thick) Surgeon: many surgeons Control group No ureteric stent, but otherwise treated identically to the stent group
Outcomes	Reported outcomes MUC UTI: positive culture > 105 Haematuria, no definition Death Breakage Migration/malpositioning Encrustation Expulsion
Notes	Additional information Funding: not reported Two graft losses to stents Donor source: cadaveric, live, multiorgan
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	No mention of the method of random sequence generation
Allocation concealment (selection bias)	Unclear risk	Did not report on allocation concealment and no information on the whole randomisation process
Blinding of participants and personnel (performance bias)	Unclear risk	Did not report any blinding within this trial, therefore unable to judge bias of this domain
Blinding of outcome assessment (detection bias)	Low risk	There is no information provided regarding knowledge of allocated interventions by outcome assessors. However, outcomes are objective with clear definitions therefore low risk of bias in this domain
Incomplete outcome data (attrition bias) All outcomes	Low risk	Author includes all relevant information regarding the predetermined outcomes
Selective reporting (reporting bias)	Low risk	Primary and secondary outcomes of interest are pre‐specified, available and have been reported upon
Other bias	Low risk	No other obvious sources of bias

Charan Kumar 2016.

Study characteristics
Methods	Study design Prospective RCT Setting: single centre Country: India Duration of study: November 2012 to July 2015 Follow‐up: immediately, 4, 12 and 24 weeks postoperatively Samples were also taken when needed, depending on symptomatology. Follow‐up included urine culture, SCr, ultrasound, and Doppler examination of the graft, as per the protocol
Participants	Study characteristics Inclusion criteria: consecutive live‐related kidney transplant recipients Exclusion criteria: not reported Baseline characteristics Number: intervention group (36); control group (36) Mean age ± SD (years): not reported Sex (M/F): not reported
Interventions	Intervention group Stent type: not reported Stent calibre: not reported Stent length: not reported Stent duration: 4 weeks Antibiotic regimen: not specified directly, but mention of trimethoprim‐sulfamethoxazole use as prophylaxis Anastomosis: L‐G extravesical ureteroneocystostomy, 6‐0 double arm (13 mm) PDS suture Surgeon: no report of surgeon experience Control group No ureteric stenting but otherwise treated identically to the stent group
Outcomes	Reported outcomes UTI Urinary leak Ureteric obstruction
Notes	Additional information Funding: not reported Four patients excluded: DGF; haematoma compression and ureteric leak; renal artery thrombosis; sepsis and postoperative death
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Computer generated randomization using Rand between functions of Microsoft Excel
Allocation concealment (selection bias)	High risk	As the Rand between function on Excel was used, investigators probably knew which group allocation was next. On balance of probability, this suggests there was a lack of allocation concealment
Blinding of participants and personnel (performance bias)	Unclear risk	No reports of blinding within the trial
Blinding of outcome assessment (detection bias)	High risk	If no blinding had taken place, the clinicians knew which patients were in the stent and non‐stented groups When checking for UTI in response to symptomatology, bias could come into play if there was a disparity between thresholds of investigations, therefore under or over‐investigating in a group more than the other
Incomplete outcome data (attrition bias) All outcomes	High risk	Author did not include excluded patients in the results but the excluded patients did experience complications. Eg. One patient in Group B (non‐stent) had ureteric leak from ureteral ischemia requiring exploration and repeat ureteroneocystostomy with DJ stent
Selective reporting (reporting bias)	Low risk	Clear pre‐specified outcomes reported
Other bias	Low risk	Exclusion of patients purely because they had a urological complication (which was the outcome of the study). For example, a patent in the non‐stent group was excluded because they suffered a leak requiring stenting. Also group cross‐overs were excluded rather than analysed with ITT principle

Dominguez 2000.

Study characteristics
Methods	Study design Quasi‐RCT Setting: single centre Country: Canada Duration of study: January 1994 to December 1997 Follow‐up: 3 months
Participants	Study characteristics Inclusion criteria: first or repeat grafts from cadaveric or living donors, ability to give informed consent Exclusion criteria: undergoing multiorgan transplantation; receiving en bloc kidneys from a paediatric donor; abnormal urinary tract; ureteric lesions mandating stent placement Baseline characteristics Number: intervention group (143); control group (137) Mena age ± SD (years): intervention group (43 ± 12); control group (43 ± 12) Sex (M): intervention group (64%); control group (72%)
Interventions	Intervention group Stent type: double J Stent calibre: 6 Fr Stent length: 12 cm Stent duration: 7 to 10 days Antibiotic regimen: co‐trimoxazole 480 mg, 3 doses/week Anastomosis: L‐G Surgeon: many surgeons, no report on experience Control group No ureteric stenting but otherwise treated identically to the stent group
Outcomes	Reported outcomes MUC Urine culture > 105 bacteria plus fever/symptoms Haematuria, no definition Irritative symptoms Breakage Migration/malpositioning Encrustation Expulsion
Notes	Additional information Funding: not reported Donor source: mixed (cadaveric and live) Used an intraoperative stent for all anastomoses Attending surgeon altered treatment designation
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	The randomization sequence was generated by the study coordinator. Patients were not randomised until after the ureter had been shortened intraoperatively without complications. No mention of the specific method of generating the random sequence, but on balance of probability deemed to be at low risk
Allocation concealment (selection bias)	Low risk	Reported a clear concealment method‐ The randomised sequence was concealed from participating surgeons. Opaque sealed sequentially numbered envelopes containing the study assignments were kept on hand in the operating room
Blinding of participants and personnel (performance bias)	Unclear risk	No mention of blinding of participants within the trial. The study did not address this
Blinding of outcome assessment (detection bias)	Low risk	Does not report blinding, but clear objective definitions given for outcomes therefore low risk of bias
Incomplete outcome data (attrition bias) All outcomes	Low risk	No missing outcome data, the pre‐specific outcomes were all reported on
Selective reporting (reporting bias)	Low risk	Study protocol available and pre‐specific primary outcomes were reported. Secondary outcomes not reported. The author did also report on patients being assessed, enrolled or withdrawn prior to randomisation
Other bias	Low risk	No other obvious sources of bias reported. Appropriate ITT analysis used

Guleria 1998.

Study characteristics
Methods	Study RCT Setting: single centre Country: India Duration of study: not reported Follow‐up: 6 months
Participants	Study characteristics Inclusion criteria: live‐related kidney transplants Exclusion criteria: not reported Baseline characteristics Number: intervention group (54)l control group (54) Mean age ± SD (years): not reported Sex (M/F): not reported
Interventions	Intervention group Stent type: double J Stent calibre: not reported Stent length: 24 cm Stent duration: 14 to 21 days Antibiotic regimen: oral cephalexin 5 days Anastomosis: L‐G and L‐P Surgeon: same team Control group No ureteric stenting but otherwise treated identically to the stent group
Outcomes	MUC UTI: on culture. Weekly urine culture Graft loss Death Irritative symptoms Breakage Migration/malpositioning Encrustation Expulsion
Notes	Additional information Funding: not reported
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Method of randomisation was by computer generated numbers
Allocation concealment (selection bias)	Low risk	A robust method of randomisation which would be unaffected by physician pre‐conception
Blinding of participants and personnel (performance bias)	Unclear risk	No information given in the abstract on this domain
Blinding of outcome assessment (detection bias)	Unclear risk	No information given on blinding
Incomplete outcome data (attrition bias) All outcomes	Low risk	All patients followed up at 6 months and no missing data
Selective reporting (reporting bias)	Unclear risk	No prespecified outcomes and no clear definition of what they regard as a positive UTI diagnosis
Other bias	High risk	Available as abstract only with no protocol, no full text, and lack of any information required for risk of bias assessment above

Kumar 1998.

Study characteristics
Methods	Study design RCT Setting: single centre Country: India Duration of study: January 1994 to April 1995 Follow‐up: 16 to 32 months
Participants	Study characteristics Inclusion criteria: consecutive live and related kidney transplants Exclusion criteria: not reported Baseline characteristics Number of patients: intervention group (57); control group (43) Mean age (years): intervention group (33.8); control group (32.7) Sex (M/F): intervention group (49/8); control group (31/12)
Interventions	Intervention group Stent type: double J Stent calibre: 6 Fr Stent length: 16 cm Stent duration: 4 weeks Antibiotic regimen: co‐trimoxazole 960 mg alternate days Anastomosis: L‐G Surgeon: single surgical team Control group No ureteric stenting but otherwise treated identically to the stent group
Outcomes	MUC UTI: "positive culture"; urine culture reported separately to UTI Haematuria: no definition Graft loss Death Irritative symptoms Breakage Migration/malpositioning Encrustation Forgotten Expulsion
Notes	Additional information Funding: not reported There is a very different number of patients in each group (57 in stent group and 43 in no stent group). This suggests: Approximately 7 participants randomised to no stent received a stent at the discretion of the operating surgeon and were then analysed in the stent group. This goes against the ITT principle and would bias the results in favour of the no stent group (i.e., the magnitude of any benefits of stents would be underestimated)
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Computer generated random number table used for randomisation process
Allocation concealment (selection bias)	Unclear risk	No report of concealment in allocation
Blinding of participants and personnel (performance bias)	Unclear risk	No report of blinding
Blinding of outcome assessment (detection bias)	Low risk	No report of blinding, but clear definitions and protocol follow‐up imaging makes this low risk
Incomplete outcome data (attrition bias) All outcomes	Low risk	There was no missing outcome data
Selective reporting (reporting bias)	Low risk	All outcomes which were prespecified were reported upon adequately
Other bias	High risk	There is no information on ITT. The very different number of patients in each group (57 in the stent group and 43 in the no stent group) suggests that several patients randomised to no stent actually received a stent at the discretion of the operating surgeon and were included in the stented group for the purposes of analysis. This could bias the results in favour of the no stent group

Majeed 2022.

Study characteristics
Methods	Study design RCT Setting: single centre Country: Pakistan Duration of study: 1 January 2014 to 31 December 2015 Follow‐up: did not report specific follow‐up time but did report if leakage was present
Participants	Study characteristics Inclusion criteria: aged 20 to 40 years; any gender; kidney transplant recipients Exclusion criteria: known lower urinary tract abnormality; any iatrogenic injury to the donor ureter Baseline characteristics Number: intervention group (54); control group (54) Mean age ± SD (years): intervention group (36.22 ± 5.66); control group (38.81 ± 5.58) Sex (M/F): intervention group (35/19); control group (30/24)
Interventions	Intervention group Stent type: double J Stent calibre: not reported Stent length: not reported Stent duration: not reported Antibiotic regimen: not reported Anastomosis: modified L‐G technique; extravesical ureteroneocystostomy Surgeon: all surgeries were done by experienced surgeons Control group No ureteric stenting but otherwise treated identically to the stent group
Outcomes	Reported outcomes Incidence of urinary leakage post‐transplant
Notes	Additional information Funding: not reported Donor source: unknown graft origin
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Lottery method was adopted to randomise the patients
Allocation concealment (selection bias)	Unclear risk	No reported information on the concealment of allocations prior to assignment
Blinding of participants and personnel (performance bias)	Unclear risk	The author stated that this trial was not double‐blinded. No report if it was a single blinded trial. If it was not blinded, then it could lead to performance bias The author did not judge that the outcome is not likely to be influenced by a lack of blinding
Blinding of outcome assessment (detection bias)	Low risk	Care provider is the outcome assessor and there is a clear outcome criteria of what constitutes urinary leakage
Incomplete outcome data (attrition bias) All outcomes	Low risk	Data available on yes/no for leak in Table 3. Follow up was 30 days
Selective reporting (reporting bias)	Low risk	Clear protocol and reported results of the pre‐specified outcome
Other bias	High risk	No mention of ITT analysis

Osman 2005.

Study characteristics
Methods	Study design RCT Setting: single centre Country: Egypt Duration of study: January 2002 to March 2003 Follow‐up: 7 to 16 months
Participants	Study characteristics Inclusion criteria: consecutive isolated live‐donor kidney transplantation Exclusion criteria: intra‐operative technical difficulties; abnormal urinary tracts; < 10 years; ureteroureteral anastomosis Baseline characteristics Number: intervention group (50); control group (50) Mean age ± SD (years): intervention group (31.7 ± 11.4); control group (29.5 ± 9.6) Sex (M/F): intervention group (40/10); control group (37/13)
Interventions	Intervention group Stent type: double J Stent calibre: 5 Fr Stent length, type: 20 cm, multilength Stent duration: removed after 2 weeks Antibiotic regimen: IV amoxicillin 5 days Anastomosis: L‐G Surgeon: Same team, single institute Control group No ureteric stenting but otherwise treated identically to the stent group
Outcomes	Reported outcomes MUC UTI: positive urine culture bacteria > 105 (every other day) Haematuria: change in heparin dose required to control Graft loss Death Breakage Migration/malpositioning Encrustation Forgotten Expulsion
Notes	Additional information Funding: not reported Excluded: 2 patients were lost in the early post‐op period unrelated to the randomization process and those patients were excluded from final analysis One patient died from pulmonary embolism on 10th day A graft nephrectomy was indicated in the second patient because of graft artery thrombosis on the 6th day
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Envelope technique used to determine randomisation
Allocation concealment (selection bias)	Low risk	Blind envelope technique using opaque sealed envelopes containing study assignments
Blinding of participants and personnel (performance bias)	Unclear risk	No mention of patient, investigator or assessor
Blinding of outcome assessment (detection bias)	Low risk	No information on blinding, but unlikely to impact on the objective outcomes
Incomplete outcome data (attrition bias) All outcomes	Low risk	No missing data on the intended outcomes
Selective reporting (reporting bias)	Low risk	Standard outcomes with clear definitions
Other bias	High risk	No information on ITT. Note graft loss and death were excluded from other analyses, but for our review they will be considered outcomes

Pleass 1995.

Study characteristics
Methods	Study design RCT Setting: single centre Country: UK Duration of study: not reported Follow‐up: 3 months
Participants	Study characteristics Inclusion criteria: live and cadaveric, multiorgan Exclusion criteria: no paediatric Baseline characteristics Number: intervention group (150); control group (150) Mean age ± SD (years): not reported Sex (M/F): not reported
Interventions	Intervention group Stent type: double J Stent calibre: 7 Fr Stent length: 12 cm Stent duration: 3 months Antibiotic regimen: co‐trimoxazole 960 mg alternate days Anastomosis: L‐G Surgeon: operations were performed by surgeons experienced in kidney transplantation; no mention of number Control group No ureteric stenting but otherwise treated identically to the stent group
Outcomes	Reported outcomes MUC UTI diagnosed clinically (fever/symptoms) and confirmed on microscopy Haematuria: catheter clot obstruction requiring washout Breakage Migration/malpositioning Encrustation Expulsion
Notes	Additional information Funding: not reported This was a four‐armed trial, here we have combined the groups to compare stent versus no stent
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Envelope technique used to determine the randomisation
Allocation concealment (selection bias)	Low risk	Blind envelope technique used
Blinding of participants and personnel (performance bias)	Unclear risk	Unclear whether all parties of participants and personnel were blinded‐ it does not specify
Blinding of outcome assessment (detection bias)	Unclear risk	Study did not address this outcome and provided insufficient information on what was blinded. No strict definitions for obstruction or leak were given
Incomplete outcome data (attrition bias) All outcomes	Low risk	States all participants followed up for 3 months (complete follow‐up)
Selective reporting (reporting bias)	Low risk	Both primary outcomes were addressed and adequate reported on
Other bias	Unclear risk	No information on ITT analysis

SPLINT 2020.

Study characteristics
Methods	Study design Non‐inferiority RCT Setting: single centre Country: the Netherlands Duration of study: April 2014 to March 2017 Follow‐up: 12 months
Participants	Study characteristics Inclusion criteria: live donor kidney transplant Exclusion criteria: declined informed consent; < 18 years; reconstructed urinary tract or conduit after total or partial cystectomy; bladder dysfunction that required continuous or intermittent catheterization; donor kidney with duplicated ureters; FSGS that still had residual urinary output Baseline characteristics Number: intervention group (100); control group (100) Mean age ± SD (years): intervention group (52 ± 14); control group (55 ± 13) Sex (M/F): intervention group (61/39); control group (63/37)
Interventions	Intervention group Stent type: single J (Teleflex) Stent calibre: 7‐fr suprapubic externalised Stent length: not reported Stent duration: removed 9 days postoperatively Antibiotic regimen: not reported Anastomosis: L‐G; extravesical ureteroneocystostomy Surgeon: not reported Control group No stent
Outcomes	Reported outcomes Probability of a PCN insertion during a 12‐month follow‐up relating to urological complications which needed stenting Indications for PCN insertion: urinary leak or rise in creatinine combined with hydronephrosis Graft function: based on GFR, surgery duration, perioperative blood loss, any surgical re‐intervention performed within < 12 months of kidney transplantation, length of hospital stay, haematuria, UTI and graft rejection < 1 month after kidney transplantation
Notes	Additional information Funding: " This study was supported by Stichting Coolsingel."
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Randomization was performed with a concealed opaque envelope system prepared by an independent statistician at the Erasmus MC, University Medical Center, Rotterdam
Allocation concealment (selection bias)	Low risk	Patients were randomised after intubation in the operating room
Blinding of participants and personnel (performance bias)	Low risk	Blinding was not possible due to use of externalised stent but unlikely to impact on outcome of major urological complication requiring intervention after the stent was removed
Blinding of outcome assessment (detection bias)	Low risk	Blinding was not possible due to use of externalised stent ‐ but unlikely to impact outcome assessment of major urological complication requiring intervention
Incomplete outcome data (attrition bias) All outcomes	Low risk	The authors included all relevant information regarding predetermined outcomes, all patients were followed up within the correct time frame and there was no missing data
Selective reporting (reporting bias)	Low risk	Clear prespecified definitions
Other bias	Low risk	No other clear and obvious sources of bias

Zaki 2013.

Study characteristics
Methods	Study design RCT Setting: single centre Country: Pakistan Duration of study: January 2008 to 31 December 2012 Follow‐up: 1 to 4 years (average 2.12 years)
Participants	Study characteristics Inclusion criteria: live‐related donors Exclusion criteria: hyperacute rejection; severe bladder abnormalities Baseline characteristics Number: intervention group (150); control group (150) Mean age ± SD (years): not reported Sex (M/F): not reported
Interventions	Intervention group Stent type: double J Stent calibre: not reported Stent length: not reported Stent duration: removed within 3 to 4 weeks Antibiotic regimen: 3rd generation cephalosporin as prophylactic antibiotic Anastomosis: L‐G; extravesical ureteroneocystostomy Surgeon: performed by the same surgical team Control group No ureteric stenting but otherwise treated identically to the stent group
Outcomes	Reported outcomes Incidence of urological complications Urological complications include: Ureteric leakage Stent migration Ureteric necrosis Ureteric stenosis Haematuria leading to intervention Symptomatic vesicoureteric reflux UTI Lymphocele leading to obstruction Lower urinary tract symptoms
Notes	Additional information Funding: not reported
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	High risk	Did not report the method of sequence generation. Unclear if this was truly randomised or quasi‐randomised
Allocation concealment (selection bias)	High risk	Did not report any information on allocation concealment, and virtually no information on the entire randomisation process
Blinding of participants and personnel (performance bias)	Unclear risk	Did not report any blinding within this trial, therefore unable to judge bias of this domain
Blinding of outcome assessment (detection bias)	Unclear risk	No blinding of outcome assessors and no clear definitions of the outcomes in question
Incomplete outcome data (attrition bias) All outcomes	Low risk	There was little data in relation to outcomes, there was missing data in relation to P values however the overall results were not significant anyway
Selective reporting (reporting bias)	Low risk	Author reported on the appropriate outcomes
Other bias	High risk	Did not pre‐publish a protocol or register the study on a trials database

DGF: delayed graft function; FSGS: focal segmental glomerulosclerosis; GFR: glomerular filtration rate; ITT: intention to treat; L‐G: Leisch Gregoir; L‐P: Leadbetter‐Politano; M/F: male/fermale; MUC: major urological complication; PCN: percutaneous nephrostomy; RCT: randomised controlled trial; SCr: serum creatinine; SD: standard deviation; UTI: urinary tract infection

Characteristics of excluded studies [ordered by study ID]

Study	Reason for exclusion
Asadpour 2011	Wrong intervention: compared length of ureteric spatulation
Battaglia 2005	Wrong intervention: compared different types of stent
Dadkhah 2010	Wrong intervention: compared anterior and posterolateral ureteroneocystostomy techniques
DRKS00015038	Wrong intervention: compared standard ureter splint versus a novel magnetic ureter splint
Gunawansa 2011	Wrong intervention: compared early versus late stent removal
Huang 2012	Wrong intervention: compared early versus late stent removal
Indu 2012	Wrong intervention: compared early versus late stent removal
ISRCTN89369862	Wrong intervention: compared umbilical vein catheters versus DJ stent insertion
Liu 2017	Wrong intervention: compared early versus late stent removal
Moray 2005	Wrong design: "RCT" however on contacting author used a historical cohort of patients "randomly chosen" as controls for the treatment group
Nadjafi‐Semnani 2020	Wrong comparator: no control group without a stent
NL‐OMON21650	Wrong intervention: compared double J stenting versus externalized single J stenting
Pansaksiri 2023	Wrong intervention: no stent arm
Parapiboon 2012	Wrong intervention: compared early versus late stent removal
Smith 2012a	Wrong intervention: compared umbilical vein catheters versus DJ stent insertion
Taghizadeh‐Afshari 2014	Wrong intervention: compared stent attached to Foley catheter to conventional technique (stent separated from Foley)
Tavakoli 2007	Study design error: prospective RCT; however, ITT analysis and randomisation flawed. "Clerical error" in the randomisation process led to significantly different numbers from protocol in each group. 11/112 (c.10%) of patients in No Stent group removed from analysis. Contacted author team and asked for details of these patient outcomes; unfortunately data not available; therefore the study had to excluded
TCTR20210204005	Wrong comparator: compared two types of stents (4.8 Fr DJ stents and 6 Fr DJ stents)
TrUST 2011	Wrong intervention: compared early versus late stent removal
Verma 2002	Wrong intervention: compared early versus late stent removal
Wongtreeratanachai 2023	Wrong comparator: compared different size stents
Yari 2014	Wrong intervention: compared optimal time for removing stent
Zargar 2005	Wrong intervention: compared two different surgical techniques (Taguchi versus modified Lich‐Gregoir)

RCT: randomised controlled trial

Characteristics of ongoing studies [ordered by study ID]

CTRI/2018/05/013647.

Study name	Stent vs no stent in ureteroneocystostomy in live related renal transplant: a prospective randomized controlled trial
Methods	Study design RCT Method of generating randomization sequence: computer‐generated randomisation Method of allocation concealment: sequentially numbered, sealed, opaque envelopes Blinding and masking: open‐label Setting: single centre Country: India Follow‐up: 3 months
Participants	Inclusion criteria: all patients undergoing Live Related Renal Transplant Exclusion criteria Paediatric kidney transplantation (< 18 years) Cadaveric kidney transplantation Patients with previous urinary bladder surgery Patients undergoing re‐transplantation Patients refusing consent Live unrelated renal transplant Target sample size: 100
Interventions	Intervention group Double J stent Control group No stent
Outcomes	Planned outcomes UTI: 1, 3, 7, 2nd week, 3rd week, 4th week, end of 2nd month and end of 3rd month Haematuria Pus cells in urine Anastomotic leak Ureteric stricture formation
Starting date	Date of registration: 3 May 2018 Date of first enrolment: 16 June 2018 Recruitment completed: 31 October 2019
Contact information	Name: Dr Souvik Dey Email: dr.asurikrishna@gmail.com Affiliation: AIIMS, New Delhi Name: Dr Asuri Krishna Email: dr.asurikrishna@gmail.com Affiliation: AIIMS, New Delhi
Notes

UTI: urinary tract infection

Differences between protocol and review

Within the most recent review, a thorough risk of bias assessment using the risk of bias 1 tool (Higgins 2022) was implemented; the study quality in previous reviews was assessed independently by CHW and AAB without blinding to authorship or journal using the checklist developed for the Cochrane Renal Group. Discrepancies were resolved by discussion with DMM.

We also removed the intervention protocol requiring the stent to be in situ for 14 days for an adequate treatment period. This was in light of increasing evidence that even short durations of stenting can be beneficial. In addition, our group performed a separate review demonstrating that earlier stent duration following kidney transplantation was not associated with a higher risk of MUC (Thompson 2018).

Contributions of authors

Writing of review: LGP, SJT, CHW, AAB, DMM
Screening of titles and abstracts: CHW, AAB, LGP, SJT
Quality assessment: LGP, SJT, CHW
Data extraction: LGP, SJT, CHW, AAB
Data analysis: LGP, SJT, CHW, AAB, DMM
Resolution of discrepancies/disagreements: CHW

Sources of support

Internal sources

• No internal sources of support, UK

External sources

• NIHR Blood and Transplant Research Unit, UK, UK

  This study was supported by the National Institute for Health Research (NIHR) Blood and Transplant Research Unit in Organ Donation and Transplanation at the University of Cambridge, in collaboration with Newcastle University and in partnership with the National Health Service Blood and Transplant (NHSBT). The views expressed are those of the review authors and not necessarily those of the National Health Service, the NIHR, the Department of Health or NHSBT.

Declarations of interest

• Laurence Patterson: No relevant interests were disclosed

• Samuel Tingle: No relevant interests were disclosed

• David Rix: No relevant interests were disclosed

• Derek Manas: No relevant interests were disclosed

• Colin Wilson: No relevant interests were disclosed

New search for studies and content updated (no change to conclusions)