Currently, percutaneous nephrolithotomy (PCNL) and URS are the two primary surgical methods commonly used in urology clinics for the treatment of larger upper ureteral stones [14, 15]. PCNL can achieve satisfactory stone clearance for larger upper ureteral stones. According to certain research, PCNL achieves an 85–100% success rate for treating upper ureteral stones larger than 15 mm [16]. Nevertheless, PCNL is atraumatic open surgery and may result in severe complications such as unbearable pain, hemorrhage and damage to adjacent organs after the procedure [17, 18]. Postoperative bleeding is always a potential disadvantage of PCNL surgery. Some studies have shown that the rate of bleeding after PCNL is 14%-24%, and 0.8% of cases may require interventional embolization to halt the bleeding [19]. URS is a surgical procedure operated through the body's natural lumen, which has the advantages of less trauma and faster recovery. It is a safe and effective endoscopic surgery for the treatment of ureteral calculi [20, 21]. Because upper ureteral stones are located nearby the renal pelvis, they are more likely to migrate upward during R-URS. This can necessitate the use of a stone blocker, or F-URS, in addition to R-URS [22], which increases treatment costs and operating times. As a result, the use of R-URS for upper ureteral stones is limited. Currently, F-URS is a commonly used treatment for proximal ureteral stones less than 20 mm in diameter [6]. It is safe and effective in treating upper urinary tract stones. Research has indicated that prolonged ureteroscopic procedures are linked to a higher incidence of complications. Therefore, it is recommended that attempts be undertaken to restrict the procedure duration to under 90 minutes [23]. The application of F-URS in the treatment of larger stones necessitates longer surgical procedures to attain the intended outcome, which could potentially lead to a higher incidence of complications following the procedure. In fact, it has been discovered that F-URS not only has a high stone retention rate when treating stones larger than 20 mm in diameter, but it is also more probably to cause complications like serious infections and stone bit formation [8]. Furthermore, F-URS is still expensive and delicate[24]. As of now, it seems that urology clinics lack a surgical method for treating large upper ureteral stones that can combine high stone clearance efficiency with minimal trauma.
A closed-circulation "water channel" forms between the Sotn-URS negative-pressure irrigation suction device and the collecting system. The use of vacuum suction removes larger stone fragments and dust in time, lowering the pressure on the renal pelvis and enhancing the visibility of the surgical field. Currently, Sotn-URS demonstrates greater efficacy and sees more frequent usage for upper urinary tract stones [9, 10, 25]. However,less research has been done on its effectiveness with larger stones. Referencing Diomidis G [26]and Bozkurt IH[16], this study compared the clinical efficacy and safety of Sotn-URS with F-URS using upper ureteral calculi with a diameter ≥ 15 mm as inclusion criteria.
The study's findings indicated that the Sotn-URS group underwent a shorter operation than the F-URS group(45.82 ± 18.81 vs. 54.21 ± 23.05 min; P = 0.036), a higher SFR of one day after operation (47.92% vs. 24.56%; P = 0.004), and a higher SFR of one month after operation (87.50% vs. 73.68%; P = 0.030). With a large sample of data, Li [9]et al. investigated the efficacy of the novel semirigid Sotn ureterorenoscope in the treatment of proximal ureteral or renal pelvis stones. They discovered that the SFR was 86.5% and the operative time was 40 (30–70) mins. All the results of our present study are fairly similar to those that were reported. Additionally, a study by Zhang[27]et al. discovered that the novel vacuum suction ureteroscopic lithotripsy for upper ureteral stones can significantly improve the SFR, with a stone-free rate at 3–5 days of up to 90.0% and a stone-free rate at 1 month of up to 96.4%, when compared to traditional ureteroscopic laser lithotripsy. The clinical outcomes of Sotn-URS in the treatment of larger upper ureteral stones were obviously effective as shown by research results.
This study revealed that for stones with a CT numerical value of ≥ 1000 Hu, the Sotn-URS group operative time was significantly shorter than the F-URS group (45.36 ± 20.26 vs. 58.51 ± 24.75 min;P = 0.006)and had a higher SFR of one day after operation(43.28% vs. 15.38%;P = 0.003༉. These findings suggest that Sotn-URS is also more beneficial for treating stones with a high CT numerical value and a large diameter, as it can both shorten the operative time and achieve a higher stone clearance efficiency. The main cause of Sotn-URS's capacity to reduce operative time and increase SFR is its special negative pressure suction effect, which can remove larger stones concurrently with lithotripsy, lessen leftover stone fragments, and reduce stone escape. All of these elements increase the efficiency and SFR while also reducing operative time. By modifying the pressure valve of the negative pressure suction, the intra-operative pressure in the ureter and renal pelvis can be regulated, thereby decreasing the likelihood of stone escape, the rate of stone retention, and the risk of stone bit formation following surgery. Furthermore, the negative pressure suction effect can draw out the air bubbles, blood clots, and gravel created during the stone crushing process, making the surgical field of view clearer, reducing operative time, and increasing stone removal efficiency.
The overall postoperative complications in the Sotn-URS group were lower than in the F-URS group in terms of complication rates (7.3% vs.19.3%;P = 0.026). The Sotn-URS group also had a lower postoperative complication rate than the F-URS group(5.97% vs. 20.51%;P = 0.050༉for stones with CT numerical value ≥ 1000 Hu. During endourological procedures, inadequate drainage or improper irrigation can result in increased pressure in the renal pelvis and increased absorption of the flushing fluid. These factors can raise the risk of complications like infection and fever. Exceeding 3.99 kPa (30 mmHg) [28] of renal pelvic pressure can cause various types of renal damage, including fluid reflux or extravasation, infection spread, urinary sepsis, and infectious shock [29]. The Sotn-URS group's postoperative fever rate in our current study was 2.08%, which is similar to the 1.7% reported by Gan et al [30]. Furthermore, Wu [31]et al.'s study discovered that the novel vacuum suction ureteroscopic laser lithotripsy(VS-URS) group's fever rate was noticeably lower than that of the traditional ureteroscopic laser lithotripsy (T-URS) group. The results of the relevant studies showed that Sotn-URS has a higher safety and fewer postoperative complications, which may be related to the fact that Sotn-URS has a significant negative pressure suction effect. By adjusting the negative pressure suction device, the surgeon can actively control the suction force, maintaining low pressure in the renal pelvis. These maneuvers may reduce the incidence of complications such as bleeding, infection, and septic shock caused by elevated renal pelvis pressure. Continuous convection water circulation created by negative pressure suction can quickly remove heat produced by the holmium laser lithotripsy procedure [32], reduce ureter thermal damage, and lower the risk of surgical complications like ureteral injuries, avulsions, and even perforation. Overall, upper ureteral calculi with a diameter ≥ 15mm can be safely treated by Sotn-URS.
In theory, Sotn-URS is a more beneficial method of treating impacted upper ureteral stones because of its ability to achieve "simultaneous lithotripsy and stone removal" and timely relief of ureteral obstruction through the utilization of negative pressure suction. In fact Wu [31]et al.'s study discovered that the VS-URS is an effective modality for impacted upper ureteral stones, and has a shorter operating time,a lower fever rate, less stone retropulsion, and a higher primary stone-free rate compared with T-URS.
However, this research has certain limitations, including a small sample size and a non-randomised retrospective design, as well as data sourced from a single institution. In order to further validate the current findings, we need to carefully organize a large-sample, multicenter, randomized, controlled prospective study in the future.