The Safety and Efficacy of Sotn ureteroscopy for Renal and Upper Ureteral Calculi: A Prospective Multicenter Randomized Controlled Trial

doi:10.21203/rs.3.rs-3215758/v1

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Research Article

The Safety and Efficacy of Sotn ureteroscopy for Renal and Upper Ureteral Calculi: A Prospective Multicenter Randomized Controlled Trial

https://doi.org/10.21203/rs.3.rs-3215758/v1

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Purpose

Sotn ureteroscopy is a new lithotripsy procedure developed on the basis of ureteroscopy and includes a rigid ureteral access sheath, standard mirror, lithotripsy mirror, and Sotn perfusion aspirator. Thus, we performed a prospective multicenter randomized controlled trial comparing the safety and efficacy of Sotn ureteroscopy in the treatment of renal and upper ureteral calculi.

Materials and Methods

224 patients with renal and upper ureteral calculi were randomly divided equally into study and control groups from March 2018 to March 2022. All of the patients were approved by the hospital ethics committee (proof number: ZF-2018-164-01 and ZF-2018-165-01) of the Second Affiliate Hospital of Guangzhou University of Chinese Medicine in China. The primary outcome was stone-free rate (SFR) assessed by computed tomography on the 1st day and month after treatment and operation duration. The secondary outcome was postoperative complication rate.

Results

In total, for upper ureteral calculi, the SFR of 1 day after operation of the Sotn ureteroscopy group was significantly higher than the rigid ureteroscopy group (83.6% vs. 60%, P = 0.006). Moreover, operative time (33.7 ± 1.80 vs. 52.9 ± 2.73 min, P < 0.005) of the Sotn ureteroscopy group was significantly lower than the rigid ureteroscopy group. Additionally, the SFR of 1 day after operation and operative time for the study group (Sotn ureteroscopy combined with flexible ureteroscopy) and the control group (flexible ureteroscopy alone) were 63.2% and 36.8% (P = 0.005), 65.6 ± 4.06 and 80.3 ± 4.91 (P = 0.023), respectively. However, there were no significant differences in the SFR of 1 month after operation, success rate of ureteral access sheath placement, and postoperative complications between the two groups (P > 0.05). In subgroups with stone diameters ≥ 1.5 cm and stone CT values ≥ 1,000 Hounsfield units, Sotn ureteroscopy showed more advantages in terms of the SFR of 1 day after operation. Importantly, complications such as ureteral injury, sepsis, fever and severe haematuria were not statistically different between the two groups (P > 0.05).

Conclusions

For renal and upper ureteral calculi, Sotn ureteroscopy has the advantage of a higher SFR of 1 day after the operation, a shorter operative time and low complication rates, suggesting that the Sotn ureteroscopy may have further potential applications in clinics.

renal calculi

upper ureteral calculi

Sotn ureteroscopy

stone-free rate

randomized controlled trial

Urinary calculi are one of the most common diseases in urology. Patients with severe stone obstruction may cause kidney damage and affect the physiological function of the kidneys. Currently, the main treatment modality for renal and upper ureteral calculi is minimally invasive surgical treatment, which is also the current trend. The current treatment options for renal and upper ureteral stones are extracorporeal shock wave lithotripsy (ESWL), percutaneous nephrolithotripsy (PNL), ureteroscopic lithotripsy (URL) and flexible ureteroscopy (F-URL).^1,2 It is well known that PCNL is safe and effective in achieving high stone free rates (SFR), but the risk of bleeding and patient pain scores are higher compared to other procedures.^3,4 Moreover, F-URL has also been widely used in clinical practice for the treatment of kidney and upper ureteral stones. However, F-URL can only be used to retrieve stones using lithoplasty blue, which is less efficient. Moreover, postoperative infection is one of the most common complications of F-URL, and in severe cases a systemic inflammatory response syndrome or even septic shock may occur.^5,6 F-URL require constant fluid flushing to maintain a clear view, which can lead to the absorption of bacteria and endotoxins into the bloodstream, increasing the risk of post-operative infection.⁷ The incidence of fever and urosepsis in the non-suctioning ureteral access sheath group of F-URL was higher and accounted for 13.9% in the retrospective study and no significant difference was noted in the incidence of hematuria. Hence, the clinical significance of postoperative urinary tract infections should not be overlooked.^8,9

Currently, there are limitations in the treatment of upper urinary tract stones via the natural channel technique, such as stone displacement, inability to achieve simultaneous lithotripsy, risk of sepsis due to pelvic hypertension, low stone removal rates and the need to change equipment between techniques. However, there is no technique that can overcome or improve on these limitations currently. Here, negative pressure combined with ureteroscopy, also known as Sotn ureteroscopy, is a new lithotripsy procedure that has emerged in China in recent years. Sotn ureteroscopy can remove stones while crushing them, reducing the risk of residual stone fragments and the formation of stone streets after the procedure. In addition, the Sotn ureteroscopy maintains the renal pelvis at a low pressure through vacuum suction to reduce damage to the kidney as well as reducing the risk of infection and bleeding due to the length of the procedure. Hence, we conducted a randomized controlled prospective multicenter clinical trial comparing the surgical outcomes of Sotn ureteroscopy for renal and upper ureteral calculi.

2.1. Study Design and Participants

We conducted a prospective, multi-institutional randomized controlled trial of patients who were diagnosed with renal and upper ureteral calculi and treated with Sotn ureteroscopy (patent certificates were shown in supplementary material) and Sotn ureteroscopy combined with F-URL in the Second Affiliate Hospital of Guangzhou University of Chinese Medicine from March 2018 to March 2022. The study was approved by both the ethics committee and the review board of our hospital (No. ZF-2018-164-01 and ZF-2018-165-01) and was performed according to the Declaration of Helsinki and the Clinical Trials Act. Our study was also registered with the Chinese Clinical Trial Registry (RCTs042190074). All of the patients provided written informed consent for participation.

In total, inclusion criteria of the study are listed as follows: 1) age 18–65 years and either sex; 2) upper ureteral stones between 0.8 and 2 cm in size; 3) individual renal stones less than 2.5 cm in size and less than 3 cm in total; 4) all patients underwent urinary tract CT [noncontrast computed tomography (NCCT) examinations; 5) patients were informed and consented to this study. Exclusion criteria are also mentioned and are listed below: patients with urinary tract abnormalities such as severe urethral strictures, cardiopulmonary dysfunction, coagulation disorders, or those who cannot tolerate surgical treatment.

For upper ureteral stones, the patients were divided into the Sotn ureteroscopy group (55 cases) and the rigid ureteroscopy group (55 cases). In addition, in the patients diagnosed with renal stones, they were divided into the Sotn ureteroscopy group (107 cases) and the Sotn ureteroscopy combined with flexible ureteroscopy group (107 cases).

2.2. Outcome Assessment

The primary outcomes include SFR of 1 day after the operation, SFR of 1 month after the operation, success rate of ureteroscopic sheathing, and operative time. Moreover, SFR was assessed according to the urinary tract CT scan on the 1st day and 1st month after the surgery. Importantly, the primary SFR was defined as no residual stones seen intraoperatively or a maximum residual stone diameter of ≤ 4 mm on postoperative CT or a residual stone diameter of ≤ 4 mm measured intraoperatively under direct vision using a 200um holmium laser. Complications were assessed and classified according to the modified Clavien-Dindo classification system,⁹ which including ureteral injury, fever (temperature > 38.5°C), severe haematuria, sepsis, and the rate of secondary surgery.

2.3. Main Surgical Instruments and Materials

For a detailed description of the Sotn ureteroscope, please see the following website: http://sotnmedical.com. The Sotn ureteroscope consists of a standard ureteroscope (length 45 cm, outside diameter 7.5 (tip)/11.3F (shaft); Patent No. ZL201110030512.9), a gravel ureteroscope (length 46 cm, outer diameter 4 (tip)/6 F [shaft]; patent no. ZL201120029461.3), a modified UAS (metal material, tapered tip, no hydrophilic coating, length of 40 cm and outer diameter of 11.6 or 12.9 F; Patent no. ZL201430394938.7), an irrigation and vacuum suction system (Patent No. ZL201420607795.4), the Lumenis Holmium laser (maximum power, 100 W), and an adapter (Patent No. ZL201430394936.8 and ZL201520891360.5).

2.4. Surgical Technique

General anesthesia is applied and the patient is placed in the truncated position. The standard scope and rigid ureteral access sheath are combined, guided by an F3 ureteral stent tube, entered through the urethral orifice and passed up to the upper ureter or renal pelvis orifice, where the rigid outer sheath is left in place and the standard scope is withdrawn. A special negative pressure suction device is then attached to the end of the rigid sheath and connected to the Sotn perfusion suction device to form a closed loop between the collecting system and the negative pressure system, and then a good working channel is established. The gravel ureteroscope enters the collection system through the operating hole of the negative pressure suction sheath, and a 200 um holmium laser fibre is inserted to break up the stone into fragments with a power of 8–30 W (0.4–1 J/20–30 Hz). The lithotripsy process is accompanied by the use of a negative pressure suction device to remove stone fragments and powder. The infused fluid and fine fragments can be aspirated by negative pressure through the space between the gravel ureteroscope and the modified rigid sheath. The operator can adjust the negative pressure suction device with the left hand to control the amount of negative pressure and thus actively control the rate of aspiration of drainage fluid and fragment by observing the degree of pelvic and ureteral dilation. It is recommended to set the perfusion mode of the medical perfusion pump to "continuous", the perfusion level to "1" and the negative pressure to 5-6Kp. For unmanageable stones in the lower renal calyces, the gravel ureteroscope is withdrawn and a flexible ureteroscope is placed inside the rigid outer sheath to fragment the stone into large particles and then flush them out using water pressure or remove them with a stone basket to the renal pelvis or calyces accessible by the gravel ureteroscope, and then replace them with the gravel ureteroscope for lithotripsy. After examination of the renal pelvis and calyces with no obvious stone fragments, discontinue perfusion and negative pressure suction. The gravel ureteroscope is withdrawn and replaced by a standard scope, which is fastened to the modified rigid sheath. The standard scope and the modified rigid sheath are withdrawn simultaneously under direct vision, and the mucosal damage to the renal pelvis and ureter is observed while withdrawing the scope (see animated video for details in supplementary material).

2.5. Statistical analysis

All statistical analyses were conducted with the Stata statistical software (version 15.0; serial number: 10699393; StataCorp Wyb). Continuous variables were expressed as means (standard deviation-SD). Independent t-tests were used to compare differences between groups. Categorical variables were compared using the X² test. We considered P-value < 0.05 values to be statistically significant.

3.1 Efficacy and Safety Analysis of Sotn Ureteroscopy

In the group of patients with upper ureteral stones receiving Sotn ureteroscopy, there were 41 men and 14 women, the mean age of patients was 48.5 ± 1.37 years, the mean body mass index (BMI) was 25.7±0.32, the CT value of the stones was 908.95±37.61 Hounsfield units (HU), the mean diameter of the ureteral stones was 1.10±0.05 cm, and the mean preoperative creatinine was 96.0±5.93 umol/L. Moreover, for patients with upper ureteral stones receiving rigid ureteroscopy, there were 33 men and 22 women, the mean age of patients was 45.1±1.43 years, the mean BMI was 25.1±0.40, the CT value of the stones was 905.75±28.72 HU, the mean diameter of the ureteral stones was 0.97±0.05 cm, and the mean preoperative creatinine was 93.4±5.65 umol/L. However, no significant difference was observed among patients in basic information such as gender, age, BMI, preoperative white blood cell count, preoperative creatinine, preoperative blood neutrophil ratio, the diameter of the ureteral stone, the CT value of stones, and the degree of preoperative hydronephrosis (P > 0.05, Table 1).

The SFR of 1 day after operation of the Sotn ureteroscopy group was significantly higher than the rigid ureteroscopy group (83.6% vs. 60%, P = 0.006). Moreover, operative time (33.7±1.80 vs. 52.9±2.73 min, P < 0.005) of the Sotn ureteroscopy group was significantly lower than the rigid ureteroscopy group (Table 1). In subgroups with stone diameters ≥1.5 cm and stone CT values ≥1,000 HU, Sotn ureteroscopy showed more advantages in terms of the SFR of 1 day after operation (Table 3). However, there were no significant differences in the SFR of 1 month after operation and success rate of ureteral access sheath placement between the two groups (P > 0.05) (Table 1). In terms of complications, the incidence of ureteral injury, sepsis, fever and severe haematuria was low and not statistically different between the two groups (P > 0.05) (Table 2).

3.2 Efficacy and Safety Analysis of Sotn Ureteroscopy Combined with Flexible Ureteroscopy

In the Sotn ureteroscopy combined with flexible ureteroscopy group, there were 36 men and 21 women, the mean age of patients was 50.5±1.45 years, the mean BMI was 24.5±0.38, the CT value of the stones was 892.2±38.0 HU, the mean diameter of the ureteral stones was 1.93±0.08 cm, and the mean preoperative creatinine was 87.0±5.58 umol/L. Nevertheless, in the flexible ureteroscopy group, there were 37 men and 20 women, the mean age of patients was 47.5±1.72 years, the mean BMI was 24.6±0.36, the CT value of the stones was 876.3±41.5 HU, the mean diameter of the ureteral stones was 1.74±0.09 cm, and the mean preoperative creatinine was 86.2±7.02 umol/L. We could not observe significant difference between two groups of patients in all general information (P > 0.05, Table 4).

Additionally, the SFR of 1 day after operation and operative time for the study group (Sotn ureteroscopy combined with flexible ureteroscopy) and the control group (flexible ureteroscopy alone) were 63.2% and 36.8% (P = 0.005), 65.6±4.06 and 80.3±4.91 (P = 0.023), respectively (Table 4). The effectiveness of the study group was equally significant in subgroup analysis with stone diameters ≥1.5 cm and stone CT values ≥1,000 HU regarding the SFR of 1 day after operation (Table 6). However, no significant differences were detected in the SFR of 1 month after operation and success rate of ureteral access sheath placement between the two groups (P > 0.05) (Table 4). Finally, complications such as ureteral injury, sepsis, fever and severe haematuria were not statistically different between the two groups (P > 0.05) (Table 5).

At present, there are many means of treating upper urinary tract stones. Percutaneous nephrolithotomy has the advantages of efficient and rapid stone extraction and high stone removal rate, but there is a risk of serious complications such as haemorrhage, pneumothorax, infection and adjacent organ damage.¹⁰ Ureteroscopy via the natural channel is relatively safe and has become one of the most important means of treating upper urinary tract stones. Hyams et al. reported a high SFR of 83% with flexible ureteroscopy for renal stones ≤ 2 cm.¹¹ In recent years, a large number of studies in China have also confirmed that flexible ureteroscopy is safe and effective in treating kidney stones with a maximum diameter > 2 cm kidney stones is safe and effective.¹² However, there are still some shortcomings in rigid ureteroscopy and flexible ureteroscopy: stones in the upper ureter can easily escape, the repeated entry and exit of the mirror can easily damage the ureter, the success rate of sheathing for beginners is not high and can easily injure the mucosa or even cause perforation.¹³ More attention needs to be paid to that the intraoperative perfusion pressure is relatively high and stones cannot be actively expelled, and the prolonged use of the flexible ureteroscopy can easily cause wear and tear.

Previous studies have reported the advantages of good efficacy, high safety, rapid postoperative recovery and few complications in the treatment of kidney stones with the Sotn ureteroscopy, but there is a lack of multicentre, randomized controlled clinical studies. The results of this study showed that the Sotn ureteroscopy has the following characteristics and advantages:

The ureteral sheath can be inserted under direct vision. The rigid ureteral sheath is placed simultaneously with the standard scope under direct vision, and in the event of ureteral torsion or stricture, a guide wire, catheter guidance or techniques such as compression of the scope itself to complete the placement until the target site is reached. Compared to the blind pushing of a conventional flexible ureteroscope UAS, it is easier for beginners to get started and less likely to damage the ureter, shortening the learning curve.

The SFR and the lithotripsy was more efficient. Due to the intraoperative use of negative pressure active suction, when dealing with stones in the upper ureter, the Sotn ureteroscopy enables perfusion and reflux to circulate within the sheath, and air bubbles, blood clots and debris produced during lithotripsy can be aspirated, resulting in a clear view and high efficiency of stone clearance when compared to conventional rigid ureteroscopy. In addition, the negative pressure suction can hold the stone in place, which not only reduces stone escape, but also greatly reduces the burn rate of the Holmium laser on the ureteral mucosa by lithotripsy in the hard sheath. During lithotripsy of kidney stones, the stone particles and powder can be directly aspirated within the UAS sheath to achieve integration of stone crushing and clearing. The SFR of 1 day after operation of the Sotn ureteroscopy in our study was 83.6%, higher than the 67. 6% reported in other large samples in the literature.¹⁴ Moreover, the rigid and flexible scopes can be used alternately, improving the efficiency of lithotripsy, saving the operation time and reducing the use of soft scopes. Our studies have shown that the SFR of the Sotn ureteroscopy is equally high for large upper ureteral stones and stones > 2 cm in the middle and upper renal calyces.

Post-operative complications are low. Fever or even severe sepsis after surgery via the natural cavity is the most serious complication of intracavitary surgery. The Sotn ureteroscopy uses a controlled negative pressure suction device, which allows for active intraoperative control of the magnitude of the attraction by the operator, minimising the pressure in the renal pelvis. The results of this study showed that the most common postoperative complication was fever, with a fever rate of 3.6% in Sotn ureteroscopy group alone and 3.5% in Sotn ureteroscopy combined with flexible ureteroscopy group, which we believe is related to the low pressure in the renal pelvis.

Our study is the first large-scale randomized controlled study to investigate the safety and efficacy of Sotn ureteroscopy for renal and upper ureteral calculi. However, there are also certain limitations of this study that need to be mentioned. For example, in our study, the number of cases in both groups was relatively small and we look forward to our next study with a larger size sample. Secondly, the Sotn ureteroscopy does not allow for real-time monitoring of actual renal pelvic pressure and should be further improved in the future.

The study showed that Sotn ureteroscopy is a safe and effective minimally invasive procedure for the treatment of renal stones and upper ureteral stones. Post-operative complications were also significantly reduced, although there was no statistical difference between the two groups of patients. Hence, Sotn ureteroscopy should be given more consideration by urological clinicians and has a good clinical future. Moreover, we hope to develop an immediate intraoperative intracavitary pressure sensing system to regulate the amount of water in and out of the cavity to achieve precise and rapid pressure control in real time in the future.

Author Contributions: Conceptualization, Shusheng Wang, Shu Gan, Songtao Xiang; Data curation, Zhenlang Guo, Zhichao Wang, Xiangtao Weng; Formal analysis, Chiming Gu, Qianming Zou, Yuan Li; Investigation, Yanquan Tang, Deneng Wu, Fan Cheng, Bin Chen, Huilong Tang, Jinsheng Cui; Methodology, Zhenlang Guo, Zhichao Wang, Xiangtao Weng; Project administration, Zhenlang Guo; Resources, Shusheng Wang; Supervision, Shusheng Wang; Validation, Shusheng Wang; Writing—original draft, Zhenlang Guo, Zhichao Wang, Xiangtao Weng; Writing—review and editing, Zhenlang Guo, Zhichao Wang, Xiangtao Weng. All authors have read and agreed to the published version of the manuscript.

Funding: This work was supported by Grants of the Guangzhou Municipal Health Commission, Guangzhou Regional Chinese and Western Medicine Collaborative Clinical Major Innovative Technology Project.

Institutional Review Board Statement: This clinical trial was approved by the Ethic Committee of The Second Affiliate Hospital of Guangzhou University of Chinese Medicine and conducted under their supervision (IRB number: ZF-2018-164-01 and ZF-2018-165-01).

Informed Consent Statement: Informed consent was obtained from all participants involved in the study.

Data Availability Statement: The datasets used and analyzed in the current study are available from the corresponding author upon reasonable request. The data are not publicly available because of privacy and ethical restrictions.

Conflicts of Interest: The authors declare no conflict of interest.

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Table 1. Comparison of the basic information and surgical effect in the two groups of upper ureteral calculi.

Variables	Total	Sotn group	Rigid group	P value
Cases	110	55	55	*
Sex (Male/Female)	74/36	41/14	33/22	0.104
Age	46.8±1.0	48.5±1.37	45.1±1.43	0.053
BMI	24.4±0.26	25.7±0.32	25.1±0.40	1
Calculi size (cm)	1.03±0.33	1.10±0.05	0.97±0.05	0.052
Calculi CT numerical value (HU)	907.35±24.82	908.95±37.61	905.75±28.72	0.621
Pre-operative hydronephrosis (mild/moderate/severe)	76/28/6	36/19/5	40/9/1	0.052
Pre-operative blood leucocytes (×10⁹/L)	7.87±0.26	7.99±0.42	7.75±0.31	0.327
Blood neutrophil percentage (%)	63.7±0.94	63.7±1.37	63.8±1.29	0.516
Pre-operative creatinine (umol/L)	94.7±4.08	96.0±5.93	93.4±5.65	0.375
Pre-operative uric acid (umol/L)	376.6±9.49	393.2±12.59	380.0±13.95	0.05
Pre-operative haemoglobin (g/L)	143.1±1.49	143.6±2.28	142.8±1.86	0.261
Pre-operative urinary tract infection	6.4% (7/110)	7.3% (4/55)	5.5% (3/55)	0.696
SFR of 1 day after operation	71.8% (79/110)	83.6% (46/55)	60% (33/55)	0.006
SFR of 1 month after operation	96.4% (106/110)	98.2% (54/55)	94.5% (52/55)	0.308
Operation time (min)	43.3±1.87	33.7±1.80	52.9±2.73	<0.001
Success rate of UAS placement	89.1% (98/110)	90.9% (50/55)	87.3% (48/55)	0.541
Post-operative urinary tract infection	21.8% (24/110)	16.4% (9/55)	27.3% (15/55)	0.166
Post-operative stone composition (calcium oxalate/calcium phosphate/uric acid)	100/9/1	50/4/1	50/5/0	0.574

Table 2. Comparison of the surgical complication in the two groups of upper ureteral calculi.

Variables	Total	Sotn group	Rigid group	P value
Ureteral injury	7.3% (8/110)	3.6% (2/55)	10.9% (6/55)	0.142
Fever (>38°C)	4.5% (5/110)	3.6% (2/55)	5.5% (3/55)	0.647
Sepsis	2.7% (3/110)	1.8% (1/55)	3.6% (2/55)	0.154
Severe haematuria	8.2% (9/110)	7.3% (4/55)	9.1% (5/55)	0.150

Table 3. Subgroup analyses of SFR in the two groups of upper ureteral calculi.

Variables	Total	Sotn group	Rigid group	P value
Stone diameter ≥ 1cm	66% (33/50)	76.5% (26/34)	43.8% (7/16)	0.023
Stone CT value ≥ 1000HU	54.3% (19/35)	81.3% (13/16)	31.6% (6/19)	0.012

Table 4. Comparison of the basic information and surgical effect in the two groups of renal calculi.

Variables	Total	Sotn & flexible group	flexible group	P value
Cases	114	57	57	*
Sex (Male/Female)	73/41	36/21	37/20	0.845
Age	49.0±1.13	50.5±1.45	47.5±1.72	0.181
BMI	24.6±0.26	24.5±0.38	24.6±0.36	0.875
Calculi size (cm)	1.84±0.06	1.93±0.08	1.74±0.09	0.126
Calculi CT numerical value (HU)	884.3±28.0	892.2±38.0	876.3±41.5	0.778
Pre-operative hydronephrosis (mild/moderate/severe)	17/80/14/3	4/47/5/1	13/33/9/2	0.054
Pre-operative blood leucocytes (×10⁹/L)	7.00±0.21	6.71±0.20	7.29±0.36	0.162
Blood neutrophil percentage (%)	61.1±0.91	62.5±1.29	59.6±1.25	0.110
Pre-operative creatinine (umol/L)	86.6±5.52	87.0±5.58	86.2±7.02	0.946
Pre-operative uric acid (umol/L)	382.1±9.18	379.9±11.92	384.3±14.07	0.813
Pre-operative haemoglobin (g/L)	140.1±1.81	138.4±2.70	141.9±2.42	0.333
Pre-operative urinary tract infection	10/114	3/57	7/57	0.185
SFR of 1 day after operation	50% (57/114)	63.2% (36/57)	36.8% (21/57)	0.005
SFR of 1 month after operation	72.8%（83/114）	78.9%（45/57）	66.7%（38/57）	0.087
Operation time (min)	73.0±3.25	65.6±4.06	80.3±4.91	0.023
Success rate of UAS placement	68.4% (78/114)	66.7% (38/57)	70.2% (40/57)	0.402
Post-operative urinary tract infection	43.9% (50/114)	38.6% (22/57)	49.1% (28/57)	0.647
Post-operative stone composition (calcium oxalate/calcium carbonate/calcium phosphate)	92/10/12	50/5/6	42/5/6	0.960
Stone location (upper/middle/lower/multiple calyces)	4/5/26/79	4/2/12/40	0/3/14/39	0.082

Table 5. Comparison of the surgical complication in the two groups of renal calculi.

Variables	Total	Sotn & flexible group	flexible group	P value
Ureteral injury	8.8% (10/114)	7.0% (4/57)	10.5% (6/57)	0.087
Fever (>38°C)	5.3% (6/114)	3.5% (2/57)	7.0% (4/57)	0.079
Sepsis	4.4% (5/114)	3.5% (2/57)	5.3% (3/57)	0.095
Severe haematuria	3.5% (4/114)	1.8% (1/57)	5.3% (3/57)	0.052

Table 6. Subgroup analyses of SFR in the two groups of renal calculi.

Variables	Total	Sotn & flexible group	flexible group	P value
Stone diameter ≥ 1cm	50% (41/82)	65.9% (29/44)	31.6% (12/38)	0.002
Stone CT value ≥ 1000HU	55.6% (25/45)	68.2% (15/22)	43.5% (10/23)	0.015

No competing interests reported.

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The Safety and Efficacy of Sotn ureteroscopy for Renal and Upper Ureteral Calculi: A Prospective Multicenter Randomized Controlled Trial

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1. Introduction

2. Materials and measures

2.1. Study Design and Participants

2.2. Outcome Assessment

2.3. Main Surgical Instruments and Materials

2.4. Surgical Technique

2.5. Statistical analysis

3. Results

3.1 Efficacy and Safety Analysis of Sotn Ureteroscopy

3.2 Efficacy and Safety Analysis of Sotn Ureteroscopy Combined with Flexible Ureteroscopy

4. Discussion

5. Conclusions

Declarations

References

Tables

Additional Declarations

Supplementary Files

Status:

Version 1