Urinary stone disease is a prevalent global urological condition with a steadily increasing incidence (1, 2). Upper urinary tract stones (including kidney stones and ureteral stones) constitute the predominant component of urinary stones, accounting for over 90% of cases; among these, ureteral stones represent approximately 30%–40% of all urinary stone cases (3, 4). The clinical presentation of upper ureteral stones often includes unilateral colicky pain that can significantly impair quality of life and may result in death in the worst cases (5). There are no international guidelines defining larger proximal ureteral stones, but there are isolated reports in the literature defining stones larger than 10 mm as larger proximal ureteral stones (6, 7). An impacted ureteral calculus is usually defined as a stone that has stayed in the same location in the ureter for at least two months, is unable to pass out on its own, and causes ureteral obstruction (8).

Currently, ureteroscopic lithotripsy (URS) is widely recommended for the management of mid-to-upper ureteral stones (9). However, conventional rigid ureteroscopic lithotripsy (R-URS) is associated with a significantly lower SFR and a higher risk of stone migration when treating larger upper ureteral stones (10). Although flexible ureteroscopic lithotripsy (F-URS) offers satisfactory efficacy and is considered a first-line option for upper ureteral stones, its use is limited by high costs, inferior durability, and expensive maintenance (11, 12). Moreover, particularly in elderly patients, F-URS for larger proximal ureteral stones may result in suboptimal SFR and an increased risk of complications such as severe infections and stone bit formation (13).

Recently, a novel semirigid ureteroscope integrated with a vacuum suction device was developed in China (14). It integrates the benefits of vacuum suction and perfusion in the UAS to achieve simultaneous lithotripsy and stone removal, lower intra-renal pressure, and clear surgical fields. Preliminary studies have demonstrated the safety and efficacy of the novel semirigid ureteroscopy with a vacuum suction device for treating renal pelvic and proximal ureteral stones (14, 15).

Based on the “simultaneous lithotripsy and stone removal” feature of novel vacuum suction semirigid ureteroscopy, it may theoretically have an advantage in the treatment of larger upper ureteral stones and impacted calculus. However, clinical evidence validating its superior efficacy and efficiency in such cases remains limited. Therefore, this study aimed to retrospectively evaluate the clinical efficacy of the novel vacuum suction semirigid ureteroscopy in treating upper ureteral stones larger than 10 mm and impacted calculi and further assess the efficacy by using a vacuum suction device during lithotripsy procedures.

Currently, percutaneous nephrolithotomy (PCNL) and URS are the primary surgical modalities for larger upper ureteral stones (19, 20). While PCNL achieves an 85%–100% success rate for treating larger upper ureteral stones (21), it is a traumatic endoscopic procedure associated with severe complications, including unbearable pain, hemorrhage (with reported bleeding rates of 14%–24%), and potential injury to adjacent organs (22–24). In contrast, URS, a minimally invasive approach utilizing the natural urinary lumen, offers the advantages of reduced trauma and quicker recovery and is a safe and effective endoscopic surgery for the treatment of ureteral calculi (25, 26). However, the application of conventional R-URS for upper ureteral stones is limited by a propensity for stone migration upward into the renal pelvis, often necessitating adjunctive measures such as stone blockers or F-URS, thereby increasing procedural time and cost (27). Although F-URS is an established first-line treatment for proximal ureteral stones less than 20 mm (9), its efficacy diminishes with stones larger than 20 mm, where it is associated with high stone retention rate and higher risks of complications, including serious infections and stone bit formation (13). Furthermore, F-URS is still expensive, less durable, and costly to maintain.

An extra vacuum suction device is the primary distinction between the novel vacuum suction semirigid ureteroscopy and the conventional ureteroscopy. The core mechanism of the vacuum suction device mainly consists of two parts: the negative pressure suction pump and the closed circulation working channel. The vacuum suction device has a perfusion interface and a suction interface. One side of the perfusion interface is connected to the perfusion fluid, and the other side of the perfusion interface, as well as the suction interface, is connected to the end of the UAS. The procedure described above creates a closed circulation working channel between the vacuum suction device and the collection system, allowing the external perfusion fluid to be supplied to the surgical area. Continuous and steady negative pressure is produced by the negative pressure suction pump and can be delivered to the surgical area via the previously mentioned closed circulation working channel. The use of vacuum suction can remove larger stone fragments and dust in time, lowering the pressure on the renal pelvis and enhancing the visibility of the surgical field. Based on the above characteristics of the vacuum suction device, the novel vacuum suction semirigid ureteroscopy presents a promising theoretical solution for larger upper ureteral stones and impacted calculi, potentially offering high clearance efficiency with minimal invasiveness. However, robust clinical evidence validating this potential remains scarce. Therefore, this study aimed to retrospectively evaluate the clinical efficacy of the novel vacuum suction semirigid ureteroscopy in treating upper ureteral stones larger than 10 mm and impacted calculi and further assess the efficacy by using a vacuum suction device during lithotripsy procedures.

A study reported that semi-rigid ureteroscopy for proximal ureteral stones had an average operative time of 51.03 min and an SFR of 78% (28). In addition, a study reported that flexible ureteroscopy for proximal ureteral stones had an average operative time of 60.3 min and an SFR of 95% (9). This study showed that the novel vacuum suction semirigid ureteroscopy for >10 mm upper ureteral stones had an average operative time of 43.8 min and an SFR at 1 month postoperatively of 87.8%. In addition, this study revealed that the novel vacuum suction semirigid ureteroscopy for >10 mm impacted calculus had an average operative time of 48.0 min and an SFR at 1 month postoperatively of 88.1%. According to the study's findings, the novel vacuum suction semirigid ureteroscopy seems to be able to achieve good stone clearance outcomes and efficiency for the treatment of >10 mm upper ureteral stones and impacted calculus(Figure 3). This efficacy is primarily attributable to the special negative pressure suction device, which can remove larger stones concurrently with lithotripsy, lessen leftover stone fragments, and reduce stone escape. These elements increase the efficiency and SFR while also reducing operative time. By modifying the pressure valve of the negative pressure suction, the intraoperative 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.

In this study, the SFR at 1 day postoperatively was 57.7% for >10 mm upper ureteral stones and 54.8% for impacted calculi, which appears suboptimal. This can be explained by two main factors. First, the study cohort involved larger (mean diameter >15 mm) and impacted stones. The laser fiber may find it difficult to reach the stone's core if it is heavily impacted or encircled by granulation tissue. This could lead to low gravel efficiency and the generation of sizable, difficult-to-evacuate fragments. Second, despite the suction capability, the surgeon must be skilled in the dynamic balance of negative pressure suction and perfusion flow. Inadequate suction timing or pressure, or suction tubing obstruction by larger fragments, could cause fragments to escape beyond the negative pressure suction range into the renal calyx and remain within the kidney. Postoperative imaging confirmed that most residual fragments were located intrarenal (Figure 4). While combined use with F-URS could manage such migrated fragments, this study only included cases that were successfully completed using the novel vacuum suction semirigid ureteroscopy alone.

A study reported that the rate of postoperative complications of patients with proximal ureteral stones treated with semirigid ureteroscopy was 16% (28). In addition, a study reported that the rate of postoperative complications of patients with proximal ureteral stones treated with flexible ureteroscopy was 8.4% (9). This study showed that the novel vacuum suction semirigid ureteroscopy had a rate of postoperative complications of 9.0% for >10 mm upper ureteral stones and 10.7% for impacted calculus. According to the study's findings, the novel vacuum suction semirigid ureteroscopy seems to be able to achieve safe surgical outcomes, which may be related to the fact that the novel vacuum suction semirigid ureteroscopy has a special negative pressure suction device. 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 (29), reduce ureter thermal damage, and lower the risk of surgical complications like ureteral injuries, avulsions, and even perforation.

The novel vacuum suction semirigid ureteroscopy is a surgical technique that combines negative pressure suction technology. While it can produce secure and effective surgical results in clinical practice, its use is still fraught with issues related to cost, technical accessibility and security. Firstly, compared with traditional endoscopes, it requires specialized UAS, a vacuum suction device, and ancillary equipment, resulting in higher overall procurement costs. Vacuum suction devices require regular maintenance, and UAS are worn out and replaced more frequently (especially when dealing with complex stones), leading to higher maintenance costs. Secondly, it is highly dependent on vacuum suction devices, perfusion equipment, and ancillary facilities and may be difficult to popularize in areas where medical resources are scarce (e.g., in some developing countries). Thirdly, it requires the physician to be skilled in the dynamic balance of negative pressure suction and perfusion flow, and the learning curve may be longer than that of conventional endoscopy. In addition, the rigid ureteral sheath is made of metal, and the placement of which in combination with rigid instruments may increase the risk of ureteral injury. There is a theoretically higher risk of ureteral injury for patients with large impacted ureteral stones (>10 mm) that have been in place for over two months. Such stones often induce mucosal inflammation, granulation tissue formation, edema, and fibrosis, leading to ureteral stiffness and luminal narrowing (30). Advancing the abovementioned rigid combination through narrowed or tortuous segments increases the potential for mucosal stripping, deep laceration, or even perforation. Therefore, surgeons must possess detailed anatomical knowledge and employ a “gentle and mild” technique during the insertion of the rigid ureteral sheath combination, particularly at sites of ureteral physiological narrowing.

Furthermore, a critical consideration with this novel ureteroscopy is the management of intrarenal pressure (IRP). While the vacuum suction can lower IRP, the absence of integrated pressure monitoring poses a potential risk (31). Procedures for larger and impacted stones often require prolonged laser use and higher irrigation flows to maintain visibility, which can elevate IRP and increase the risk of postoperative fever and infection (32). Furthermore, excessive suction force itself may theoretically cause ureteral mucosal bleeding or injury, a concern supported by two observed cases of minor mucosal bleeding in this study. Therefore, surgical success and safety are highly dependent on the surgeon's ability to manually maintain a dynamic balance between suction and irrigation. The current lack of integrated pressure monitoring and control devices represents a primary limitation of this novel ureteroscopy (31). Future technological iterations could significantly benefit from incorporating intelligent pressure-control systems, such as the recently reported intelligent platform that maintains a safe, real-time monitored renal pelvic pressure during F-URS (33–37). Integrating such advancements would be a crucial step forward in standardizing the safety profile of the novel vacuum suction semirigid ureteroscopy. In addition, the flexible navigable suction ureteral access sheath (FANS) represents a significant advancement in sheath technology recently, integrating continuous suction with a flexible, navigable tip (38, 39). In contrast to the rigid UAS used in our study, FANS can better conform to the natural anatomy of the upper urinary tract, potentially improving the capability to reach the renal pelvis and calyces and reducing the risk of iatrogenic injury. Its successful application in treating larger stones (20–30 mm) highlights the clinical value of combining suction with excellent flexibility (40, 41). The evolution of the novel vacuum suction semirigid ureteroscopy could draw valuable insights from these technologies in the future. Incorporating the intelligent pressure-control systems and flexible, navigable sheath designs would be a critical step toward developing next-generation devices that are both more efficient and safer.

This study provides an initial investigation into the clinical efficacy of the novel vacuum suction semirigid ureteroscopy in treating >10 mm upper ureteral stones and impacted calculus. Additionally, it offers an initial evaluation of the efficacy of utilizing a vacuum suction device during lithotripsy procedures. However, this research has certain limitations, including a lack of data on other lithotripsy procedures as a control, a small sample size, and a non-randomized retrospective design, as well as data sourced from a single institution. In the future, a carefully designed prospective study involving a large-sample, multicenter, randomized, and controlled study is required to further validate the current findings.

The novel semirigid ureteroscopy with a vacuum suction device is a safe and effective surgical procedure for the treatment of >10 mm upper ureteral stones and impacted calculus. During the lithotripsy procedure, the use of a vacuum suction device has the potential to improve stone removal efficiency. However, due to the critical limitation of the lack of integrated pressure monitoring and control devices, potential complications caused by negative pressure suction and perfusion flow imbalance should be watched out for.