Comparison of suction technique and non-suction technique in retrograde intrarenal stone surgery: a systematic review and meta-analysis

Abstract

Objective

To evaluate the clinical efficacy of retrograde intrarenal stone surgery (RIRS) using the vacuum suction technique for the treatment of upper urinary calculi.

Methods

A comprehensive literature search was conducted across multiple databases, including PubMed, Embase, Sino Med, CNKI, WANFANG DATA, and Cochrane. We included studies comparing vacuum suction RIRS with non-vacuum RIRS. Following the PRISMA guidelines, we performed a meta-analysis of the selected studies. Inclusion criteria were randomized controlled trials (RCTs), case–control studies, and retrospective studies evaluating the efficacy of these techniques. Key outcomes analyzed included operative time, hospitalization duration, stone-free rates, and complication rates. Statistical analyses were conducted using mean differences (MD) for continuous variables and odds ratios (OR) for dichotomous outcomes, with corresponding 95% confidence intervals (CI).

Results

Sixteen studies (6 RCTs, 1 case–control study, and 9 retrospective studies) involving a total of 2029 patients were included. Meta-analysis revealed that the vacuum suction technique significantly reduced operative time (MD = − 14.45 min, 95% CI [− 18.45; − 10.44], P < 0.00001) and hospital stay (MD = − 0.54 days, 95% CI [− 0.80; − 0.28], P < 0.00001). In addition, patients in the vacuum suction group had a higher stone-free rate (OR = 3.57, 95% CI [2.57; 4.95], P < 0.00001) and lower complication rates, particularly in reducing postoperative fever.

Conclusion

The application of the vacuum suction technique in RIRS significantly improves clinical outcomes by reducing operative time and hospitalization duration, enhancing stone-free rates, and lowering postoperative complication rates. This technique demonstrates a clear clinical advantage over non-vacuum RIRS and should be considered a preferred option for the management of upper urinary tract stones.

Supplementary Information

The online version contains supplementary material available at 10.1007/s11255-024-04280-6.

Introduction

Retrograde intrarenal surgery (RIRS) has increased cumulative admission and is now recognized as the main treatment for renal stones up to 2 cm in size [1]. This trend is further extended to stones larger than 2 cm, pediatric cases, and anomalous kidneys, making it a viable alternative to percutaneous nephrolithotomy (PCNL) [2–4]. Upper urinary tract calculi are a common condition with a high incidence and recurrence rate [5]. Failure to treat these stones promptly can lead to serious complications due to blockage of the collection system. Consequently, minimally invasive therapies have become the main focus of therapeutic strategies.

In recent years, the development of endoscopic technologies, such as miniaturized endoscopes, improved deflection mechanisms, enhanced optical quality, and the introduction of disposables, has significantly improved the clearance rate of RIRS for stones in the renal pelvis and upper/middle pelvis [6, 7]. Studies have shown that experienced surgeons can achieve treatment outcomes similar to those of PCNL for these types of kidney stones while benefiting from reduced trauma, making RIRS a preferred choice.

A key drawback of RIRS is the passive expulsion of stone fragments, which can extend the duration of stone passage and increase the risk of urinary tract infection and stone recurrence. To mitigate this issue, technological advancements in the form of vacuum suction sheaths have been introduced. This tool, which is an innovative variation of the conventional sheath, is engineered to connect with a negative-pressure suction catheter and is now used in RIRS.

Scientific studies suggest that this vacuum suction sheath provides considerable benefits in reducing operative time and improving stone-free rates compared to a sheath devoid of negative-pressure suction. However, its influence on postoperative complications remains debatable. Certain studies have documented significant decreases in postoperative fever rate, discomfort, and urinary tract infections [8–12]. Conversely, other research findings present no substantial variation in specific complications [13, 14].

Given the potential limitations of small sample sizes in certain clinical studies, the potential benefits of using a vacuum suction sheath to reduce postoperative complications may not have been clearly established. To assess the effectiveness of the vacuum suction sheath in terms of reducing postoperative complications, as well as its impact on operative time and stone-free rates compared with the traditional sheath in RIRS, we conducted a systematic review. This analysis involved gathering and analyzing pertinent studies sourced from reputable databases, namely PubMed, Embase, Cochrane Library, and CNKI.

Materials and methods

Using certain search keywords, we searched the databases of PubMed, Embase, (China National Knowledge Infrastructure) CNKI, and Cochrane for publications that were published before to October 28, 2024. After that, we screened the papers that we had gotten. A review was conducted on articles that used both English and Chinese. Randomized controlled trials, prospective cohort studies, and retrospective cohort studies are all included in systematic reviews and data synthesis. These studies compare conventional sheaths with negative-pressure suction sheaths. [PubMed database search keywords: (vacuum (“intelligent pressure control” [Title/Abstract] OR Suction [Title/Abstract]]] In the end, 16 publications were found based on the above search terms: 6 randomized controlled trials, 10 retrospective studies, and a total of 2029 individuals. (“Ureteroscopy” [Mesh] or “Retrograde Intrarenal Stone Surgery” [Title/Abstract]) AND (“Retrograde Intrarenal Stone Surgery” [Title/Abstract]). ‘Retrograde Intrarenal Stone Surgery’: ab,ti OR RIRS: ab,ti OR Ureteroscopy: ab,ti AND (vacuum: ab,ti OR ‘intelligent pressure control’: ab,ti OR suction: ab,ti) are the kind of procedures that are included in the Embase databases. Cochrane databases: ((vacuum):ti,ab,kw OR (intelligent pressure control):ti,ab,kw OR (suction):ti,ab,kw) AND ((MeSH descriptor: [ureteroscopy] this term only MeSH) OR ((RIRS):ti,ab,kw) OR (Retrograde Intrarenal Stone Surgery):ti,ab,kw) (Fig. 1).

Fig. 1.

The searching and screening flowchart of this systematic review

Quality assessment

Jadad scores served as a metric to evaluate the performance of the RCTs incorporated in the analysis. The Newcastle–Ottawa Scale (NOS) was employed to assess the likelihood of bias in non-randomized studies (refer to Table S1 for NOS scales and Table S2 for Jadad scores).

Inclusion/exclusion criteria

Included studies must satisfy the following PICO inclusion criteria:

1. Patients: the patient presented with upper urinary calculi, which were addressed with retrograde intrarenal stone surgery (RIRS).

2. Intervention: the suction method was the only therapy intervention.

3. Comparisons: a comparison was conducted between vacuum suction and non-vacuum suction procedures.

4. Outcomes: essential outcome data (stone-free rates and operative duration for effectiveness, complications for safety) were included in the findings.

5. Research: randomized controlled trials and both prospective and retrospective research were aggregated. Our meta-analysis excluded studies that used previously published reviews and/or meta-analyses. Furthermore, all papers now included were accessible in full text with enough data. There is no restriction on sample size for research used in the data synthesis.

Criteria for exclusivity:

1. Single-arm studies or insufficient data.

2. Chinese research excludes original studies without English titles and abstracts.

Statistical analysis

The meta-analysis utilized Review Manager 5.4, a commonly employed software for such analyses. Statistical significance was assessed using a two-tailed threshold of P < 0.05. The meta-analysis employed a random-effects model, incorporating a 95% confidence interval (CI). Given that the outcomes of the random effect model and the fixed effect model align in the absence of heterogeneity, this study utilized the random effect model to aggregate all data. The pooled results of all dichotomous variables were presented using odds ratios (OR), and the pooled results of all continuous variables were presented using mean differences (MD). Heterogeneity was evaluated through the application of Cochran’s Q statistics and I-square statistics. Publication bias was evaluated using visual analysis tools from Review Manager 5.4.

Results

The original data retrieved from 6 RCTs, 1 case–control study, and 9 retrospective cohort studies (RCS) were included in this systematic review and meta-analysis after literature screening and quality control (Table 1) [8–23]. Detailed NOS and Jadad scales are shown in Tables S1 and S2. All studies contained efficacy and safety outcomes, except the study by Harris et al., which did not have a detailed description of complications. 2029 patients were included in the quantitative analysis.

Table 1.

Basic information of included studies in this systematic review

Author	Year	Area	Study design	Sample size N(exp)/N(con)	Age	Gender (F/M)	Stone size	Stone Density
ZHANG YuBai	2021	Asia	RCT	100/100	46.91±15.77/45.99±16.76	45/55, 42/58	191.8±68.34/201.2±67.95	1044±235.5/1069±208.4
DUAN Zhiguo	2021	Asia	RCT	52/56	４６．４８±１１．７/４５．３５±１２．４	25/27, 27/29	１．１８±０．４2/１．２１±０．３８	Nr
Wu Jun-yong	2019	Asia	RCT	41/38	42.30±5.20 /41.24±5.42	41/0, 38/0	1.10±0.45/1.12±0.46	Nr
Xu Duanya	2019	Asia	RCT	40/40	51.0/51.5	15/25, 13/27	10.4±2/9.5±1.2	Nr
Du, C.	2019	Asia	RCT	62/60	47.36 (SD, 13.16) /46.95（SD，15.72）	25/37, 24,36	Maximum stone diameter: 21.88 (SD, 4.93) mm/21.37 (SD, 3.61) mm	1022.8 (215.3)/984.5 (226.8)
Lechevallier E	2003	Asia	RCT	21/26
Tang	2023	Asia	RCT	87/86	51.3 (8.2) /52.7 (9.3)		15 (5) /16 (4)
LIU Jia	2020	Asia	RCS	62/68	49.69±12.87/ 49.81±12.43	18/44, 19/49	11.82±2.15/12.19±2.14	821.81±262.87/881.04±286.47
Tian Li	2018	Asia	RCS	46/50	67.1±3.4 /65.8±3.2	26/20,28/22	nr	Nr
ZHANG KaiNeng	2022	Asia	RCS	31/31	50. 03±12. 01/49. 42±15. 93		2. 12±0. 11/2. 11±0. 10	967. 42±269. 94/834. 52±274. 49
Chen Hua	2018	Asia	RCS	145/122	45.7±11.9/ 42.9±15.9	81/64, 57/65	1.58±0.36/1.57±0.33	Nr
WuJianfa	2022	Asia	RCS	65/55	(45.90 ±1.59)/(48.90± 1.63)	30/35, 28/27	(18．30±0.38) mm/（17.80±0.39)mm
Zhai, Q.	2023	Asia	RCS	60/60/60	46.2（SD，6.9）/45.7（SD，6.5）/47.2（SD，4.5）		Stone burden (mm2) ：131.8± 25.1/136.5± 26.6/135.9± 24.8
Zhang, L. W.	2021	Asia	RCS	56/54	53.8 ± 12.1/55.2 ± 10.2	22/34, 17/37	13.9 ± 4.7/12.7 ± 5.5	708.59 ± 343.70/684.22 ± 376.30
Gauhar, V.	2022	Asia	RCS	28/30	49.0 (37.0–61.0)/46.0 (39.3–53.8)	13/15, 10/20	13.0 (11.8–15.0) / 22.0 (18.0–28.8)
Wu, Z. H.	2022	Asia	RCS	76/82	48.49 ± 12.44/44.91 ± 12.66	33/43, 36/46	165.30 ± 33.36/157.02 ± 34.59	937.73 ± 85.04/916.40 ± 80.71
Qian, X.	2022	Asia	CCS	81/81	51 (42.0, 57.0)/50.0 (43.0, 57.0)	29/52, 25/56	19.0 (17.0, 23)/20.0(17.0,23.0)	912.25(52.90)/906.48(63.47)/897.10(94.20)
Huang	2023	Asia	RCS	103/103	54.7 (10.7)/54.5 (11)		17 (5)/17 (6)
Lai	2020	Asia	RCS	56/28			38.2(5.4)/35.3(6.3)	729(83.7)/676.1(42.2)

Author	Suction devices	Control sheath	Lithotripsy	Definition of SFR	Technique used to determine stone size	Infection	Types of ureteroscope	Stone location	Quality assessment (Jadad for RCTs and NOS for non-RCTs)
ZHANG YuBai	Shuotong, F11.5/F12.5	B o s ton Scientific，F11/F13	Holmium laser（EMS，FT-211，20W）	d≤4 mm/30 days	Ultrasound+CT	Septic pyemia：qSOPA≥ 2	ureteroscope (Wolf，F8/ F9.8) 、flexible ureteroscope ( O l y m p u s ，U R F - P 6 ，F7 . 9 5)	Kidney stones	5
DUAN Zhiguo	Fr 12/14	Nr	Holmium laser（0.8-1.5J，20-30Hz）	d<0.3 cm	Ultrasound, KUB、IVP ,CT	Fever：>38 °C	Nr	Ureteral stones	4
Wu Jun-yong	Y-type negative pressure sheath	Nr	Holmium laser		Ultrasound, KUB+IVU	Nr	Ureteroscope (6-7.5 F)	ureteral stones	4
Xu Duanya	Negative pressure system	Nr	Holmium laser（1-2J，10-20Hz）	KUB shows no residual stones	Color ultrasound, KUB, IVU, CT	Nr		ureteral stones	4
Du, C.	Patented perfusion and suctioning platform		Holmium laser（0.6–0.8 J/ 25–30 Hz ，550 μm	d≤4 mm/30 days	CT，KUB, ultrasound	Nr	F7/8.4Storz ureteroscopes	Ureteral stones	4
Lechevallier E			Nr	Nr	Nr	Nr		Ureteral stones	5
Tang			Ho:YAG lithotripsy (0.8–1.0 J, 15–20 Hz), 200 μm fibre	Fragments ≤2 mm	CT, KUB			Upper ureter 86 Renal 0	5
LIU Jia	Three-way negative pressure sheath（12/14Fr	COOK 12/14Fr	Holmium laser（30W，276μm	d≤4 mm/2 weeks	CT	Fever：≥ 37.5 °C		Kidney stones	8
Tian Li	Cook 12/14 Fr		Holmium laser（nr	d≤4 mm/30 days	KUB	SIRS	Olympus URF-P5 flexible ureteroscope	Kidney stones	8
ZHANG KaiNeng	Cook	Cook	Holmium laser（100W）	d≤4 mm/2 weeks	CT, KUB	Fever：≥ 37.5 °C	ureteroscope (Wolf，F8/ F9.8)	Kidney stones	8
Chen Hua	12F	12F	holmium laser（0.8J，30Hz）	<0.3 cm	CT, KUB	Nr	Ureteroscope (7.0~8.4 F)，electronic flexible ureteroscope(11 278VU，8.5 F)	Kidney stones	8
WuJianfa			Holmium laser（1J，20Hz， 20 0 μm ）		CT, KUB, IVU		Ureteroscope (F8/9.8 Wolf)	ureteral stones ，renal pelvic stones, and kidney stones	8
Zhai, Q.	Shenzhen Kang Yi Bo Technology Development Co. Ltd.,		Holmium laser (0.6–1.0 J/20–30 Hz, 275μm)	d<4 mm/ 30 days	Ultrasound, CT, KUB		8-9.8 Fr Wolf single-channel semi-rigid ureteroscope，6.8–7.5 Fr Wolf single-channel semi-rigid ureteroscope	ureteral stones	9
Zhang, L. W.	Negative pressure system		200-μm holmium laser	d<4 mm/ 3-5 days and 30 days	CT		8/9.8 F ureteroscope	upper ureteral	8
Gauhar, V.			Holmium 100-watt laser / TFL 35 watt	the absence of a single residual fragment >3 mm or in the absence of multiple fragments of any size	CT		single-use 7.5 Fr ureteroscope Uscope, with a 11 Fr/13 Fr dual lumen SUAS ClearPetraTM/A 7.5 Fr reusable or single-use 7.5 Fr ureteroscope Uscope	Kidney	9
Wu, Z. H.	Composed of a 5F ureteral catheter and a tee joint		Holmium-YAG laser machine an energy level of 0.3–0.8 J and a frequency of 15–30 Hz	no visible stone fragments on KUB.	KUB, NCCT	38 °C	7.5 F/9.8 F semi-rigid ureteroscopes (Schoelly Fiberoptic GmbH, Germany)	upper ureteral stones	8
Qian, X.	12/14F, cook medical		Holmium laser（12-20W，14-20Hz，200μm）	d<4 mm/one day and 30 days	CT, KUB	SIRS Fever：temperature above 38.0 °C within 48 h	7.5 Fr flexible ureteroscope	Kidney stones	8
Huang			Ho:YAG Lithotripsy (1.2 J, 20 Hz)	Fragments <3 mm	CT				8
Lai				No residual fragments	CT			Ureter 0 Renal pelvis 28 Upper calyx 13 Middle calyx 15 Lower calyx 11	8

Efficacy of stone‐free assessment

A total of 16 studies involving 2029 patients were included in the assessment of stone-free rates compared to vacuum suction and conventional techniques [8–23]. The findings from the analysis revealed a statistically noteworthy difference between the two sense modalities (Fig. 2A, odds ratio [OR] = 3.57; 95% confidence interval [CI] 2.57–4.95; P = 0.37), indicating a higher likelihood of achieving a stone-free status with the vacuum suction technique. Notably, the analysis demonstrated minimal heterogeneity among the included studies (Fig. 2A, I²=0)), further supporting the consistency of our findings. For a visual representation of the data, please refer to the corresponding funnel plot, which is available in the additional file (Fig. 3A).

Fig. 2.

Forest plots of safety and efficacy comparisons between vacuum suction technique and traditional sheath. A Stone-free rate, B operation time, C hospital stay, D RPP, E PCT, F WBC, G infection, H noninfectious complications

Fig. 3.

Funnel plots of meta-analysis. A Operation time, B stone-free rate, C hospital stay, D RPP, E PCT, F WBC, G infection, H noninfectious complications

Operative time comparison

A total of 16 studies involving 2029 patients provided data comparing the operative time between the vacuum suction technique and the non-vacuum technique [8–23]. A comprehensive synthesis of these studies revealed a significant reduction in operation time associated with the suction technique (Fig. 2B, mean difference [MD] = − 14.45; 95% confidence interval [CI] − 18.45 to − 10.44). However, it is important to note that a high degree of heterogeneity was observed among the included studies (Fig. 2B, I²=97%; P < 0.00001). The heterogeneity of operation duration may be caused by different operators’ operating habits, the level of the operator’s RIRS technology, and other factors. However, it is worth noting that the mean difference for all included studies was negative, so the inference that overall negative-pressure suction technology leads to shorter surgical duration is robust. The Additional file contained the corresponding funnel plot, which can be referenced for further analysis (Fig. 3B).

Hospitalization stay comparison

Compared with the non-vacuum suction group, the hospital stay was significantly shorter (Fig. 2C, MD = − 0.54; 95% CI − 0.80 to − 0.28). 11 studies (comprising 1164 patients) provided data on this comparison [12, 14, 15, 17, 19, 21, 23, 24]. However, high heterogeneity was detected among studies (Fig. 2C I²=90%; P < 0.00001). The heterogeneity of hospitalization duration is difficult to directly assess. We speculate that in some studies, the diameter of the stones included in the study may be relatively large, so the effect of negative-pressure suction technology on hospitalization duration is more significant. When negative-pressure suction technology is applied to patients with smaller diameter stones, its advantages may be difficult to demonstrate. However, it is worth noting that the mean differences in all included studies were negative, so the inference that overall negative-pressure suction technology leads to shorter hospital stays is robust. An Additional file presents the corresponding funnel plot (Fig. 3C).

Infective complications comparison

In this meta-analysis, a comprehensive review of 13 studies involving 1742 patients was conducted to compare the incidence of infective complications between suction and conventional technique. The analysis revealed a significant disparity between the two modalities, with the suction technique displaying a lower risk of infective complications (Fig. 2D, odds ratio [OR] = 0.25; 95% confidence interval [CI] 0.16–0.38; P = 0.91).

Importantly, the results of the included studies demonstrated a consistent pattern without any heterogeneity (Fig. 2D, I²=0), indicating agreement between the findings. This suggests a reliable and consistent association between the use of the suction technique and reduced risk of infective complications.

For a more visual representation of the data, the corresponding funnel plot can be found in the additional file, providing an overview of the included studies and their respective effect sizes (Fig. 3D).

Noninfectious complications comparison

The occurrence of noninfectious complications between suction and conventional techniques was rigorously examined in a comprehensive analysis of 7 studies involving a total of 932 patients [11, 12, 15, 17, 22, 23]. The findings revealed a substantial disparity between the two approaches, with the suction technique significantly mitigating the risk of noninfectious complications (Fig. 2E, odds ratio [OR] = 0.13; 95% confidence interval [CI] 0.06–0.28; P = 0.31).

Significantly, the included studies exhibited a remarkable absence of heterogeneity (Fig. 3E, I²=0%), indicating a consistent pattern of results, reinforcing the reliability of the findings. A visual representation of the data can be found in the additional file, featuring a corresponding funnel plot for a clearer overview of the included studies and their respective effect sizes.

Comparison of RPP (renal pelvic pressure), PCT and WBC

Two [17, 19], six [12, 17, 19, 21, 22] and four studies [17, 19, 22] (comprising 204, 708, and 524 patients, respectively) provided data on RPP (Fig. 2F), PCT (Fig. 2G), and WBC (Fig. 2H), respectively. According to the overall synthesis results, there was a significant difference between the two modalities (MD = − 13.2/− 1.14/− 4.65, 95% CI [− 14.58, − 11.46]/ [− 1.63, − 0.65]/[− 9.19, − 0.11]). However, high heterogeneity was observed among the studies (I² = 66%, 99%, and 100%; P < 0.00001). It is challenging to explicitly evaluate the heterogeneity of the measured indicators in the blood. Similarly, we hypothesize that the diameter of the stones included in certain studies may be relatively large, which could result in a substantial impact on the duration of hospitalization due to negative-pressure vacuum technology. The advantages of negative-pressure vacuum technology may be challenging to demonstrate when it is implemented on patients with stones of smaller diameter. Nevertheless, it is important to mention that the mean differences in all the included studies were negative. Consequently, the inference that negative-pressure suction technology would lead to a reduced risk of infection is a robust one. An Additional file presents the corresponding funnel plot (Fig. 3F–H).

Subgroup analysis (only RCTs)

Subgroup analysis did not reveal any statistically significant contradictions with the primary analysis above (Table 2).

Table 2.

Subgroup analysis based on study design

Subgroup	Pool effect	P	Heterogeneity
Stone clearance rate
RCTs (n=7)	6.09 [1.63, 22.73]	0.007	I2=63% P=0.02
Non-RCTs (n=12)	3.57 [2.54, 5.03]	<0.0001	I2=0% P=0.93
Infection
RCTs (n=6)	0.17 [0.07, 0.39]	<0.0001	I2=0% P=0.86
Non-RCTs (n=10)	0.29 [0.17, 0.48]	<0.0001	I2=0% P=0.81
Noninfectious complications
RCTs (n=3)	0.08 [0.03, 0.26]	<0.0001	I2=0% P=0.84
Non-RCTs (n=4)	0.21 [0.05, 0.82]	0.03	I2=50% P=0.11
Surgery time
RCTs (n=6)	− 17.55 [− 24.51, − 10.59]	<0.0001	I2=94% P<0.0001
Non-RCTs (n=10)	− 12.84 [− 18.08, − 7.60]	<0.0001	I2=97% P=<0.0001

Discussion

Urinary calculi, also known as urinary stones, are among the most prevalent conditions in urological surgery departments. Ureteral stones account for approximately 12.3% of all urinary stone diseases [25]. To date, various guidelines and consensus have recommended PCNL as the preferred treatment for kidney stones > 20 mm in size. However, the complexity and surgical trauma associated with percutaneous nephrolithotomy hinders its widespread adoption [26].

In recent years, advances in flexible ureteral nephoscopy, along with improvements in material technology and surgical techniques, have significantly improved the stone clearance rate in retrograde intrarenal stone surgery (RIRS) [27]. Experienced surgeons have achieved similar treatment outcomes to percutaneous nephrolithotomy, with the added benefit of reduced invasiveness, making RIRS increasingly popular [28].

Retrograde intrarenal surgery (RIRS) has several advantages, including minimal direct harm to the patient’s kidneys and a quicker recovery period, making it a highly favorable treatment option for upper urinary calculi. However, to ensure optimal visualization during the procedure and prevent potential injury to the renal collecting system, intraoperative saline perfusion is necessary. Unfortunately, this perfusion technique leads to an increase in renal pelvic pressure (RPP). A high RPP can lead to postoperative infective complications by facilitating the admission of local bacteriological creatures and endotoxins into the bloodstream [27, 28]

Large ureteral stones present with various challenges. These often result in numerous stone fragments, making post-surgery discharge difficult. Repetitive ureteroscopic procedures for thorough lithotripsy may cause secondary ureteral injury and postoperative ureteral stricture [29–31]. The size of the stones also affects discharge time, and some patients may require secondary surgery with low success rates [32]. According to a study by Gdor et al. study [33], the success rate of transurethral ureteroscopic holmium laser lithotripsy for large ureteral stones was only 56% (5/9), and there was only one successful case in the proximal ureteral segment (1/3). Similarly, other researchers reported that for large proximal ureteral stones, the initial success rate of holmium laser lithotripsy was not satisfying [34]. The use of suctioning techniques in RIRS aims to lower the RPP and maintain clear intraoperative visualization [35]. Successful laser lithotripsy in RIRS entails complete fragmentation of stones in all locations, avoiding complications, and ensuring total removal of fragments to prevent clinically significant residual stones during follow-up [36]. However, there is no consensus on whether basketing or dusting techniques alone are superior in rendering patients stone-free post-RIRS [37, 38].

Recent attention has shifted to the utilization of suction in RIRS. Some single-center studies have reported the utility of suction sheaths [39, 40], highlighting potential benefits such as lower intrarenal temperatures, reduced pressure, minimized infective complications, improved operating times, and enhanced SFR compared to old-style RIRS. The connected vacuum suction tube creates a negative pressure that effectively removes irrigating fluid, small stone fragments, and pus moss from the renal pelvis via the sheath, thereby ensuring a clear visual field for the surgeon and expediting the operation [35]. The suction technique also provides continuous perfusion for stone crushing and facilitates rapid discharge of crushed stones, resulting in shorter operative times and improved stone-breaking efficiency [35].

During our literature review, we observed that almost all research combining negative-pressure technology and RIRS originated in China, likely due to the country’s recent economic development and doctors’ proactive adoption of new technologies. Systematic reviews have highlighted the advantages of negative-pressure techniques. These techniques offer the potential for clearer surgical vision, enabling surgeons to perform the procedures more effectively. In addition, they have the potential to reduce surgical time, leading to more efficient operations. By implementing negative-pressure techniques, hospitals may experience decreased hospital stays, providing a cost-effective solution for healthcare providers. Moreover, these techniques have demonstrated the ability to improve lithotomy rates, resulting in more successful stone removal. Furthermore, negative-pressure techniques have shown promise in decreasing postoperative complications and contributing to better patient outcomes.

Some published reviews have commented on negative-pressure techniques and have recognized that they may offer surgical performance. However, these lack clinical data and are based on in vitro or animal experiments, which can only indicate that the negative-pressure suction sheath is effective in reducing RPP [41–44]. The earliest clinical trial on this topic was conducted by the Service d’Urologie et Transplantation Rénale Hôpital Salvator in France and was published in 2003. This study focused on the use of the vacuum suction technique and its impact on ureteroscopy time. The researchers concluded that the application of this technique led to a significant reduction in the mean ureteroscopy time. In 2008, the Department of Urology at Ganzhou People’s Hospital, affiliated with Nanchang University in Jiangxi Province, China, conducted the largest clinical trial in the field. This study compared the use of negative-pressure suction sheaths with that of traditional Retrograde Intrarenal Surgery. The researchers found that the operative time in the negative-pressure group was shorter than that in the control group. In addition, the stone clearance rate was higher in the negative-pressure group, and the overall incidence of postoperative complications was lower than that in the control group.

Considering various factors such as sample size and the need for more comprehensive clinical guidance, further analyses were performed. This systematic synthesis aimed to provide a more robust conclusion regarding the effectiveness and safety of the application of negative-pressure suction sheaths versus traditional RIRS. The analysis considered parameters such as operative duration, stone clearance rate, postoperative complications, and length of hospital stay. The objective of this study was to establish the advantages of utilizing negative-pressure suction sheaths as a superior alternative to traditional RIRS. After a comprehensive search and data pooling, this meta-analysis found that using the suction technique could reduce the operative time and support the aforementioned points. However, the results showed relative heterogeneity. Our team posits that the observed high heterogeneity (e.g., operative time, length of hospitalization, PCT, and WBC) primarily arises from the limited sample size and the variability in the types of studies included. However, given the scarcity of published research in this field and the urgent need for clinical guidance in this area, we have opted to conduct and complete this study, striving to ensure the scientific rigor and robustness of our conclusions.

This study had some limitations. The meta-analysis included only six RCTs, one case control study and nine cohort studies, which might have introduced bias. Furthermore, the size and density of the stones were different in the included studies, which might have caused heterogeneity. Studies, especially RCTs with larger sample sizes, are required to obtain more reliable results.

Conclusion

Implementation of the vacuum suction sheath technique in RIRS has proven to be highly effective in addressing upper urinary tract calculi. This technique not only significantly reduced operative time and hospitalization but also demonstrated improvements in both instant and last stone-free rates. Moreover, it effectively decreases the renal pelvic pressure and minimizes postoperative problems. These promising outcomes underscore the considerable value and merit of promoting and adopting this technique. By embracing the vacuum suction sheath technique, healthcare providers can potentially enhance patient outcomes and optimize the organization of upper urinary tract calculi.

Supplementary Information

Below is the link to the electronic supplementary material.

Author contributions

P.C., G.M., and J.C.: conceptualized and designed the investigation; P.C., Y.L., and G.M.: data collection; P.C., G.M., and X.J.: data analysis and/or interpretation; P.C. and G.M.: drafted and critically revised the manuscript; K.W.: reviewed and authorized the final version of the manuscript. All the authors reviewed the manuscript. Pengan Chen and Gaoshen Mi have contributed equally to this work.

Funding

This work was supported by the Department of Science and Technology of Sichuan Province. Found ID: 2023YFS0029.

Data availability

All data generated or analyzed during this study are included in this published article and its additional files.

Declarations

Conflict of interest

The authors declare that they have no competing interests.

Ethical approval and consent to participate.

Not applicable.

Consent for publication

Not applicable.