Robot-assisted kidney transplantation for right versus left living donor kidneys: A single-center outcome and learning curve analysis

ABSTRACT

Introduction:

Robot-assisted kidney transplantation (RAKT) is the standard of care in experienced hands. Transplantation of right kidney (RK) from a living donor (LD) is challenging because the right renal vein is shorter and thinner, which can lead to underutilization of RKs from LD. Data for RK-RAKT are scarce. We aim to compare the surgical, peri-operative, and long-term outcomes after RAKT from RK donors versus left kidney (LK) donors and the learning curve (LC) for the entire RAKT cohort.

Methods:

After ethical committee approval, we retrospectively analyzed 409 adult RAKTs from LDs performed by a single surgeon between 2013 and 2021. We compared donor/recipient demographics, intra-operative data, immediate and late graft function, and graft/patient survival.

Results:

Overall, 18.5% were RK-RAKT. Donor/recipient demographics were similar between the groups. Total vascular (32.9 ± 8.9 vs. 29.6 ± 5.8 min, P = 0.003) and venous anastomosis times (14.4 ± 6.1 vs. 11.4 ± 2.5 min, P < 0.0001) were significantly longer in the RK group. No significant differences were observed in the serum creatinine and estimated glomerular filtration rate levels at day 1 and 7; 1 month; 1, 3, 5, 7, 10 years. 10-year Death-censored graft survival (77.4% for left vs. 79.17% for right, P = 0.917) and patient survival (83.9% for left vs. 75% for right, P = 0.10) were comparable. LC was shorter for critical vascular steps and graft functional outcomes.

Conclusions:

RK-RAKT achieves equivalent functional and survival outcomes to LK-RAKT. Concerns regarding vascular thrombosis are not supported by our findings. These results advocate for broader use of RK, potentially decreasing the wait times and improving the access to transplantation.

INTRODUCTION

The side of living donor nephrectomy (LDN) and its effect on the graft and recipient outcomes remains a debate even in this era.[1] Left-sided LDN is preferred by most centers because of the longer and thicker renal vein that facilitates anastomosis with the recipient’s iliac vein with ease.[2,3] Right-sided LDN is associated with technical problems of short renal vein and renal vein thrombosis (RVT) in the recipients.[4,5] Recently, robot-assisted kidney transplantation (RAKT) has been proposed as an alternative approach to open surgery, particularly due to its potential benefits for fragile and immunocompromised recipients in terms of peri- and postoperative outcomes, length of hospital stay, postoperative pain, wound infection rate, and cosmetic results.[6] When surgeons with previous experience in open kidney transplantation (OKT) and robotic surgery performed RAKT, the surgical and functional results were acceptable.[7] However, the data regarding the outcomes of RAKT with right kidney (RK) and the learning curve (LC) of RAKT are limited. Our study aims to assess and compare the surgical, early peri-operative, and long-term outcomes of RAKT from RK versus left kidney (LK) donors and to analyze the LC of the entire cohort of RAKT.

MATERIALS AND METHODS

Study population

This was a single-center retrospective analysis of LDs and their recipients who underwent RAKT at our institute between January 2013 and December 2021. The study period was defined from January 2013 to December 2024, and all the recipients were followed up for at least 3 years. The study was approved by the Institute Ethics Committee (No: EC1/2021/014; on August 9, 2021) with a waiver of informed consent for retrospective data collection. The authors confirm the availability of, and access to, all the original data reported in this study. The authors have not used artificial intelligence (AI) or AI-assisted technologies, including large language learning models, in the preparation of the manuscript. Regarding the selection of the donor side, the LK was preferred by default, and the RK was selected when the LK was unsuitable for donation due to multiple renal vessels, anatomical anomalies, or significantly higher split renal function on the left side. All donors underwent pure retroperitoneoscopic (laparoscopic) donor nephrectomy.

The technique of right-side pure retroperitoneoscopic donor nephrectomy

The technique of right-side pure retroperitoneoscopic donor nephrectomy was performed as previously described by Modi et al.[8] We describe the key technical aspects of port placement and stapler application. Three ports were placed initially: a 10 mm camera port at the tip of the 12^th rib, a 5 mm port at the anterior axillary line, and a 10 mm port at the renal angle. A 12-mm port for stapler application was kept approximately 1.5 cm above the iliac crest on the lateral aspect of the paraspinal muscles. An Endo-TA (Auto Suture, US Surgical, Norwalk, CT) stapler was applied on the Inferior vena cava (IVC). Flush to the staple line, the cuff of the IVC was divided, obtaining additional renal vein length.

Bench surgery

Stay sutures were taken at the upper edge of the artery, vein, and upper pole of the kidney for orientation. To hold the kidney in place in the pelvis, a jacket for the kidney was created by wrapping it in a single-layer gauze piece such that the hilar vessels remain exposed. For grafts with dual renal veins, on the right side both veins were procured together on a common IVC cuff and anastomosed as a single common channel to the external iliac vein (EIV); on the left side spatulation and side-to-side reconstruction to form a single channel was performed. Sometimes, ligation of small accessory veins was performed. For grafts with multiple renal arteries, reconstruction was performed using the pantaloon technique where feasible, or separate anastomosis to the external iliac artery was performed when arteries were widely separated or were of disproportionate caliber.

Technique of robot-assisted kidney transplantation

All RAKT were performed by a single surgeon who had extensive experience in OKT and laparoscopic kidney transplant[9]. Important technical aspects are described below. The recipients were placed in a 30-degree Trendelenburg and lithotomy position. A camera port was placed two fingerbreadths above the umbilicus, and robotic ports were placed eight cm apart, and an assistant port was placed between the camera port and the right robotic port. The robot was docked between the two legs. The peritoneum over the external iliac vessels was dissected. The peritoneal flap was raised lateral to the iliac vessels, taking care not to injure the genitofemoral nerve and the gonadal vessels. The bladder was dropped down. Through a 7 cm Pfannenstiel incision or the vaginal route, the kidney was dropped into the abdomen, providing better cosmesis and less pain. The external aponeurosis was closed, and the robot was redocked. Bulldog clamps were applied on the EIV, and venotomy and flushing of the vein was carried out. Gore-tex suture on a CV-6 needle was used for end-to-side anastomosis of the renal vein to the EIV. A bulldog clamp was applied on the renal vein, and bulldogs from the EIV were removed, restoring the venous drainage of the lower limb. Arterial anastomosis was carried out to the external iliac artery in a similar fashion. Bulldog clamps from the renal vein, followed by the arteries, were opened, and hemostasis was achieved. The graft was flipped onto the psoas muscle. Ureteroneocystostomy (UNC) was performed by the modified Lich-Gregoir method. We don’t use stents and drains routinely. We did not use regional hypothermia after the first 58 cases due to the consistent reduction in anastomosis times and observed benefit in graft outcomes. In the case of 2^nd and 3^rd transplants, the left external iliac vessels and right common iliac vessels were used for vascular anastomosis, respectively.

Dataset

Variables include sociodemographic data, intraoperative data, and surgical and functional outcomes. The key area of interest was the side, right or left, of the LD kidney and its recipient outcomes, respectively. Donor baseline characteristics included for analysis were age, gender, body mass index (BMI) and the number of renal arteries and veins in the donor kidney. Recipient baseline characteristics included were age, gender, BMI, blood loss, warm ischemia time (WIT), cold ischemia time (CIT), re-warming time (RWT), total console time, total vascular anastomosis time, arterial and venous anastomosis time, UNC time, serum creatinine and e-GFR at day 1 and 7; 1 month; 1, 3, 5, 7 and 10 years, graft and patient survival.

Technical graft loss was defined as graft thrombosis within seven days after transplant. Primary failure was defined as graft loss within 30 days after transplant. RWT is defined as the time between graft insertion into the abdominal cavity and revascularization.

LC and patient safety analysis were performed for the entire cohort of RAKT. We analyzed the correlation between LC and functional results with the following variables (arterial and venous anastomosis times, UNC time, RWT, and estimated glomerular filtration rate (eGFR) at post-operative day 30– pretransplant eGFR [eGFR30-pretx]).

Statistical analysis

The collected data were entered into Microsoft Excel and analyzed with IBM SPSS Statistics for Windows, Version 29.0. (Armonk, NY: IBM Corp). To describe the data, descriptive statistics, frequency analysis, and percentage analysis were used for categorical variables, and the mean and standard deviation (SD) were used for continuous variables. To find the significant difference between the bivariate samples in independent groups, the independent sample t-test was used. To find the significance in qualitative categorical data, the Chi-square test was used; similarly, if the expected cell frequency was <5 in 2 × 2 tables, then Fisher’s Exact test was used. To assess the relationship between the variables, Pearson correlation was used. To find the cumulative death-censored graft survival and patient survival, the Kaplan–Meier curve was used with the log-rank method.

We used a cumulative summation (CUSUM) chart to analyze the LC and Shewart control chart (SCC) to monitor patient safety. The target and SD values for CUSUM and SCC were set referring to the outcomes of procedures by Breda et al. (target + 2SD = alert threshold, target + 3SD = alarm threshold).[10] An exception was made in setting the RWT target value at 45 and an SD of 15 min based on Wickham’s experiment.[11]

RESULTS

A total of 514 LD nephrectomies and RAKTs were performed. Patients with missing data were excluded (25). Pediatric recipients (80 of which 5 recipients received RK) were excluded as these populations are expected to have variable demographics and outcome profiles that may be inadequately captured by the measured variables. A total of 409 adult recipients and donors were analyzed.

Donor characteristics and operative data

Of the 409 donors, 76 (18.58%) underwent right and 333 (81.42%) underwent left donor nephrectomy. RK grafts were utilized throughout the entire study period and were not confined to the later phase of the program. Of the 76 right donor kidney RAKTs, 28 (36.8%) were performed during the first 103 consecutive RAKTs, and 52 (68.4%) were completed within the first half of the study period (first 205 cases), indicating that right donor kidneys were adopted early in our experience. This chronological distribution indicates that RK grafts were incorporated from the early experience onward and were not selectively reserved until after completion of the LC, minimizing the likelihood of temporal selection bias. There was no statistically significant difference between the mean age, gender, and the BMI of RK and LK donors. Out of the 54 multiple renal arteries on the left side, 4 donors had triple renal arteries, and the rest had double renal arteries. 12 right-side donors had dual renal arteries. A significantly higher proportion of RK donors had dual renal veins (14.4% vs. 3.9%, P = 0.0005). On the right side, linear staplers were used for augmenting the renal vein length with IVC cuff in 39 donors whenever needed; in nine donors, hem-o-lok clip was used to control the vein. On the left side, retroaortic renal vein was seen in 8 donors, and 13 donors had circumaortic renal vein. Complete duplication of ureters was seen in two donors on the right side and one on the left side. There was no statistically significant difference between the mean donor operative times and blood loss between the right and left LDN. There was no mortality in either group [Table 1].

Table 1.

Donor characteristics and operative data

Donor characteristics	LK donor (n=333), n (%)	RK donor (n=76), n (%)	P
Age (year), mean±SD	48.6±9	46.3±8.3	0.42
Female/male, n (% femaDle donors)	254/79 (76.3)	57/19(75)	0.814
BMI (kg/m2), mean±SD	25±4.5	25.2±5	0.791
Multiple renal arteries	54 (16.2)	12 (16.4)	0.996
Dual renal vein	13 (3.9)	11 (14.4)	0.0005
Operative time (min), mean±SD	131.1±66.3	125.6±49.5	0.424
Blood loss (min), mean±SD	46.8±30.7	44.2±32.7	0.507

SD=Standard deviation, BMI=Body mass index, LK=Left kidney, RK=Right kidney

Recipient characteristics and operative data

The baseline characteristics, age, gender, and BMI of the recipients in the two groups were comparable. RK recipients had significantly longer WIT and RWTs (187.4 ± 54.5 vs. 140.6 ± 51.1 seconds, P = 0.0005; 46.4 ± 11.7 vs. 41.4 ± 8.5 min, P = 0.001). The total operative time and console time were significantly longer in the RK recipient group (206 ± 57.7 vs. 185.6 ± 42.6 min, P = 0.005; 144.7 ± 44.7 vs. 127.4 ± 37.2 min, P = 0.002). Arterial anastomosis time, UNC time, and blood loss were comparable between the two groups. Total vascular anastomosis time and venous anastomosis time were significantly longer in the RK recipients compared to the left (32.9 ± 8.9 vs. 29.6 ± 5.8 min, P = 0.003; 14.4 ± 6.1 vs. 11.4 ± 2.5 min, P = 0.00004). Technical graft loss occurred in one right renal allograft due to venous thrombosis. One LK recipient with dual renal arteries reconstructed with pantaloon developed a pseudoaneurysm within 2 weeks of transplant; it was managed by re-exploration and pseudoaneurysm repair. Urinary leak occurred in two cases, managed by exploration and ureteric reimplantation; both were from the left-side allografts [Table 2]. One case required laparoscopic-guided percutaneous graft biopsy without any complication since the RK was kept in the true pelvis as it could not be flipped over the psoas muscle and was not retroperitonealized.[12]

Table 2.

Recipient characteristics and operative data

Recipient characteristics	LK recipient (n=333)	RK recipient (n=76)	P
Age (year), mean±SD	34.7±10.5	35.3±11.2	0.661
Female/male, n (% female recipients)	46/287 (13.8)	17/59 (22.4)	0.062
BMI (kg/m2), mean±SD	20.6±3.9	21±4.2	0.403
WIT (s), mean±SD	140.6±51.1	187.4±54.5	0.0005
CIT (min), mean±SD	92.6±51.1	88.2±40.4	0.485
RWT (min), mean±SD	41.4±8.5	46.4±11.7	0.001
Operative time (min), mean±SD	185.6±42.6	206±57.7	0.005
Console time (min), mean±SD	127.4±37.2	144.7±44.7	0.002
Blood loss (min), mean±SD	52.7±92.1	50.7±88.8	0.863
Total vascular anastomosis time (min), mean±SD	29.6±5.8	32.9±8.9	0.003
Arterial anastomosis time (min), mean±SD	12.9±2.9	13.1±3.8	0.643
Venous anastomosis time (min), mean±SD	11.4±2.5	14.4±6.1	0.00004
UNC time (min), mean±SD	29±7.2	31.4±11.4	0.802

UNC=Ureteroneocystostomy, SD=Standard deviation, BMI=Body mass index, LK=Left kidney, WIT=Warm ischemia time, CIT=Cold ischemia time, RWT=Re-warming time

Functional outcomes

Figure 1a and b reflects the serum creatinine levels and eGFR of both the left and RK recipients; both curves show a progressive improvement in the renal function. There was no significant difference in the serum creatinine (mg/dl) at day 1, day 7, 1 month, 1, 3, 5, 7 and 10 years between the LK and RK recipients respectively (day 1-1.84 ± 1.27 vs. 2.09 ± 1.36, P = 0.138; day 7-1.75 ± 5.35 vs. 1.66 ± 1.2, P = 0.881; 1 month - 1.28 ± 0.52 vs. 1.37 ± 0.81, P = 0.217; 1 year - 1.37 ± 0.67 vs. 1.29 ± 0.53, P = 0.366; 3 years-1.4 ± 0.64 vs. 1.32 ± 0.54, P = 0.285; 5 years-1.44 ± 0.57 vs. 1.33 ± 0.54, P = 0.285; 7 years - 1.46 ± 0.6 vs. 1.46 ± 0.68, P = 0.95;10 years-1.41 ± 0.45 vs. 1.53 ± 0.91, P = 0.614). Also, there was no significant difference in the e-GFR (ml/min/1.73 m²) at day 1, day 7, 1 month, 1, 3, 5, 7 and 10 years between the LK and RK recipients respectively (day 1-56.55 ± 26.4 vs. 52.48 ± 29.5, P = 0.63; day 7-69.48 ± 29.3 vs. 65.4 ± 28.19, P = 0.239; 1 month - 77.29 ± 26.06 vs. 72.95 ± 27.08, P = 0.198; 1 year-70.77 ± 26.06 vs. 73.49 ± 24.79, P = 0.404; 3 years - 64.26 ± 22.77 vs. 68.72 ± 26.83, P = 0.25; 5 years - 62.78 ± 22.38 vs. 68.13 ± 26.53, P = 0.179; 7 years - 62.18 ± 21.59 vs. 60.13 ± 24.96, P = 0.671;10 years - 61.5 ± 21.63 vs. 64.13 ± 30.18, P = 0.78).

Figure 1.

Comparative outcomes between right and left kidney recipients. (a) Serum creatinine trajectory over time in recipients of right versus left donor kidneys. (b) Estimated glomerular filtration rate trajectory over time in recipients of right versus left donor kidneys. (c) Kaplan–Meier curve depicting death-censored graft survival in right versus left donor kidney recipients. (d) Kaplan–Meier curve showing overall patient survival in right versus left donor kidney recipients

Causes of all-cause graft loss and patient loss

Between 2013 and 2024, 123 recipients lost their graft. RKs accounted for 27 (35.5% of the RK recipients) of the grafts lost compared to the LK accounting for 96 (28.8% of LK recipients). The most common cause of graft loss was death with a functioning kidney that occurred in 36.5% of LK and 48.1% of RK recipients. Technical cause of graft loss was seen in only one recipient, who received the RK, who lost the graft due to RVT and expired subsequently. Primary non-function (primary failure) accounted for one recipient of RK and three recipients of LK.

A total of 55 recipients (15 patients who received RK and 40 patients who received LK) died during the study period. The most common cause of death in both the groups was infection, primarily pneumonia. The causes of death in the RK recipients were infections (46.67%), cardiovascular disease (40%), and one patient each died due to intracerebral hemorrhage and RVT. Causes of death in the LK recipients were infections (55%), cardiovascular disease (37.5%), and one patient each died due to cerebrovascular accident, acute liver failure, and aspiration.

Kaplan–Meier estimates of death-censored graft and patient survivals:

Death-censored graft and patient survival at 1, 3, 5 and 10 years have been listed in Table 3. At 10 years, overall graft survival was 71.1% for LKs and 64.4% for RKs. The death-censored graft survival at 10 years was comparable, and there was no significant difference between the two groups (77.4% for left vs. 79.17% for right, log-rank P = 0.917). Patient survival was not significantly different between LK and RK recipients at 10 years (83.9% for left vs. 75% for right, log-rank P = 0.10) [Table 3 and Figure 1c, d].

Table 3.

Death-censored graft survival and patient survival

	1 year (%)	3 year (%)	5 year (%)	10 year (%)	Overall event (graft/patient loss), n	Survival (censored), n	Log rank P
Death-censored graft survival
Left	96.7	91	82.7	77.4	61	272	0.917
Right	94.7	85.5	84.72	79.17	14	62
Patient survival
Left	95.5	92.2	89.08	83.9	40	293	0.10
Right	96.05	89.47	80.6	75	15	61

Cumulative summation analysis

The LC for arterial anastomosis required up to 12 cases, and venous anastomosis required up to nine cases. The plateau for RWT was achieved after 132 cases. Unlike arterial and venous anastomosis times, which reflect a single focused technical step that is mastered relatively early, RWT is a composite measure spanning graft positioning through completion of both vascular anastomoses to revascularization. Its CUSUM curve therefore reflects the cumulative effect of multiple sequential steps and overall operative coordination, rather than a single skill, which explains why its cumulative deviation took longer to stabilize compared to the individual anastomosis times. Difference between eGFR on postoperative day 30 and preoperative eGFR (eGFR [30-pretx]) stabilized after 22 cases [Figure 2a].

Figure 2.

(a) Cumulative sum analysis illustrating the learning curve for robot-assisted kidney transplantation (RAKT). (b) Shewhart control chart demonstrating procedural consistency and safety across sequential RAKT cases

Shewhart control charts

Arterial anastomosis time was below the alert/alarm threshold in 99%/99.5% of the RAKTs, while 99.5% of the venous anastomosis time was below the alert/alarm threshold. The RWT was below the alert/alarm threshold in 98.8%/99.8%. The UNC time was below the alert/alarm threshold in 87.9% and 90.2% of the cases, respectively. The eGFR differences (30 days postoperative) were at least 25 and 35 ml/min/1.73 m² in 94.2% and 86.9%, respectively [Figure 2b].

DISCUSSION

To the best of our knowledge, this is the largest single-center comparative study on outcomes of RAKT from RK vs. LK LDs. The only other similar study published is a multicenter study by the ERUS-RAKT working group.[7,13,14] Our study uniquely offers: (1) homogeneous single-surgeon data minimizing inter-operator variability; (2) long-term follow-up data of up to 10 years for both death-censored graft survival and patient survival-currently sparse in the RK RAKT. In our study, the recipient’s mean operative time, console time, WIT, RWT, vascular anastomotsis and venous anastomosis times were significantly longer in the RK recipient group, but it did not affect the post-operative functional outcomes and long-term survival outcomes. In the ERAS-RAKT working group study, there were no significant differences in the median first WIT and median CIT between the groups. While the median times to complete venous (17 min in each group) and arterial anastomoses (16 min in each group) were comparable between RK-RAKT and LK-RAKT, the median RWT and overall operative time were longer in the RK group (46 vs. 43 min, P = 0.004 and 228 vs. 210 min, P = 0.002, respectively) and no significant differences in median eGFR at the last follow-up (52 vs. 53 ml/min/m²). Both these studies on RAKT of RKs have shown that RK was not associated with poor functional outcomes.

A retrospective analysis of the ANZDATA registry of OKT between 2004 and 2018 reached similar conclusion and reported that the patient and graft survival beyond 30 days was not associated with LD kidney side.[15] However, they showed that right LD kidneys have a twofold increased risk of delayed graft function (DGF), graft loss, and death-censored graft loss within the first 30 days of transplant. Two meta-analyses have also shown that RKs were not associated with increased risk of DGF or graft loss at 1 year.[16,17] In our study, contrastingly, there were no differences in the early functional outcomes between the groups. Our data demonstrate a technical graft loss rate of <1% within the first 30 days, providing robust evidence to support broader utilization of RKs. Thus, our study shows the RK-RAKT results are comparable to those of RK-OKT.

Data on important factors such as increased WIT on the right donor nephrectomy may be attributable to the use of a linear stapler. Longer re-warming, operative and console time, as well as vascular and venous anastomosis times on the right side could suggest that there are increased surgical challenges with RK-RAKT. The longer venous anastomosis time in the RK group (14.4 ± 6.1 vs. 11.4 ± 2.5 min) is attributable to two reasons (1) fragile and shorter veins on the right side, which require more meticulous suturing to avoid tension and tearing and (2) the significantly higher proportion of RKs with dual renal veins (14.4% vs. 3.9%). In these cases, both veins were procured together with a common IVC cuff using the stapler technique described in the Methods section, resulting in a wider venous orifice for implantation. Anastomosis of this wider cuff to the EIV required a longer circumferential suture line, accounting for the increased anastomosis time. The longer RWT on the right side is explained by this same prolonged vascular anastomosis process, since RWT spans from graft insertion to revascularization and is therefore directly influenced by the anastomosis duration.

Many studies have observed the RKs to be at increased risk of thrombosis.[5,18,19,20] In our study, during the early days, one right renal allograft with dual renal veins was lost due to RVT, likely due to technical reasons, suggesting that there is no significantly increased risk of graft thrombosis associated with RK-RAKT.

There has been increasing uptake of RAKT with initial studies indicating that it is non-inferior to OKT and feasible with multiple vessel grafts.[7,21] The outcomes of our present RK vs. LK RAKT study are promising and consistent with other RAKT studies, and RAKT can be considered as an alternative to the open approach in other centers with experience in robotic surgery and kidney transplantation. The shorter renal vein of RKs is particularly challenging in obese recipients and recipients with a narrow pelvis in the setting of the OKT. During RAKT, the kidney lies in the true pelvis medial to the iliac vein; this, along with the magnification and dexterity of robotic surgery, is very advantageous as it facilitates tension-free vascular anastomosis even in the case of short renal veins. However, implementation of this technique requires appropriate training and extensive experience in both robotic surgery and OKT.

CUSUM analysis confirmed that LC for vascular anastomosis was shorter and functional outcomes stabilized early (22 cases), indicating greater proficiency and reliable transplantation results. Plateau of RWT after 132 cases reflects broader operative efficiency improvements over time.

SCC analysis demonstrates excellent procedural consistency and safety in RAKT. Vascular anastomosis times remained below the alert and alarm thresholds in more than 99% of the cases, which highlights a stable and reproducible surgical technique. RWT was similarly well controlled, staying within the safe limits in 98.8% to 99.8% of the cases. Although UNC time showed slightly more variability, with 87.9% and 90.2% of the cases remaining within alert and alarm thresholds, respectively, the majority still demonstrated acceptable performance. eGFR differences were within the safe thresholds (≥25 and ≥35 ml/min/1.73 m²) in 94.2% and 86.9% of the cases, respectively, indicating that functional outcomes were never compromised.

The limitations of the present study are its retrospective design, missing data related to the causes of graft loss, and single-center, single-surgeon design. A prospective design was not feasible given the long recruitment period (2013–2021) required to accumulate an adequately powered cohort of RK-RAKT cases, which are inherently less common. However, data were drawn from a prospectively maintained institutional database of all consecutive adult primary kidney transplant recipients at our center, which minimizes recall and selection bias. The single-surgeon design limits the generalizability across surgeons but removes inter-surgeon variability as a confounding factor. The marked imbalance between the groups (76 right vs. 333 left) reflects real-world practice, where RKs are inherently less frequently utilized owing to the surgical concerns regarding the shorter renal vein – a pattern consistent with virtually all published series on this topic, including the multicenter ERUS-RAKT data. This imbalance reduces the statistical power, particularly for detecting smaller differences in less common outcomes such as graft loss and survival; a true difference of smaller magnitude between the groups cannot be entirely excluded, and our findings should be interpreted with this constraint in mind. In addition, the LC analysis was performed for the entire RAKT cohort rather than being stratified by kidney side, as RK and LK cases were performed concurrently throughout the study rather than in sequential phases and a separate LC analysis for RK grafts alone was not feasible given the small subgroup size, which would have limited the statistical robustness of an independent CUSUM analysis. Strengths of this study include the large single-center cohort with long-term follow-up of up to 10 years. Nearly one-fifth of the donor nephrectomies and transplants included RK; our data provide a robust comparison of donor as well as recipient outcomes from a single-center.

CONCLUSION

The results of our study are significant in addressing the concerns surrounding the use of RK for RAKT. Despite the technical challenge and longer RWT and vascular anastomosis times for RK-RAKT, it did not translate into inferior functional or survival outcomes, reinforcing the safety of RK utilization in RAKT. We have shown that RK-RAKT is associated with a very low risk of vascular thrombosis and yields comparable functional and survival outcomes to LK-RAKT. Consequently, patients in the need of renal transplantation should not be denied this opportunity based solely on the donor kidney’s laterality. Our data provide crucial evidence for clinicians to counsel recipients effectively and should encourage broader consideration of RKs, thereby potentially shortening the wait times and increasing the access to transplantation.

Findings of our LC analysis suggest that RAKT can be effectively and safely performed with a relatively short LC for critical vascular steps, and with excellent recipient outcomes once surgical proficiency is achieved.

Conflicts of interest

There are no conflicts of interest.

Funding Statement

Nil.