Abstract
Background and Objective
Among the complications of ureteroscopic lithotripsy, withdrawal difficulties due to ureteroscopic impaction have not been well studied. Most of the existing literature is limited to single-center retrospective analysis or small-sample case reports. The purpose of this article is to elucidate the causes of intraoperative ureteroscopic impaction, summarize relevant research evidence, and propose effective prevention and management strategies.
Methods
Through a systematic search of PubMed and Web of Science spanning from 1999 to 2024, English and Chinese literature containing keywords such as “ureteroscopy”, “difficult ureteroscope withdrawal”, “ureteroscopic impaction”, and “ureteral injury” were included. The search covered retrospective studies, case reports, and experimental studies.
Key Content and Findings
This review identified that the primary causes of ureteroscopic impaction encompass operator-related factors, instrumental characteristics, ureteral anatomical strictures, pathological strictures, and ureteral spasms. Preventive strategies involve comprehensive preoperative assessment, appropriate ureteroscopy selection, and meticulous procedural technique. Regarding management, mild cases may resolve spontaneously with observation, whereas severe impaction necessitates employment of specialized exit techniques.
Conclusions
This review offers clinicians comprehensive strategies for preventing and managing ureteroscopic impaction, which can help reduce surgical risks and improve patient outcomes. Further multicenter, prospective studies are necessary to optimize relevant technologies and methods in the future.
Keywords: Ureteroscope, difficult ureteroscope withdrawal, ureteroscopic impaction
Introduction
While minimally invasive ureteroscopy has revolutionized urological practice, intraoperative complications such as ureteral injury and scope impaction persist as significant challenges. Over 70% ureteral injuries are iatrogenic from improper endoscopy handling (1,2). The ureter’s narrow fragile lumen, prior-surgery scarring and physiological constrictions raise ureteroscopy-related injury and difficulty risks. Literature indicates ureteral injury incidence is 0.5–10% (3). Intraoperative complications involve full-thickness ureteral tears, mucosal lacerations, perforations, ureteral transections, liquid absorption, etc. (4). It has been demonstrated that intraoperative placement of a ureteral access sheath may induce iatrogenic injury to the ureteral mucosa (5), potentially leading to postoperative complications such as infectious ureteritis, structural strictures, and hemorrhagic events. These adverse outcomes worsen patient prognosis, prolong hospitalization, and cause more psychological distress and financial burden.
A major cause of these complications is “ureteroscope impaction” mismanagement, namely failed ureteroscope access when advancing rigid or flexible ones through ureteral segments, due to anatomical variations, pre-existing pathological strictures, severe ureteral spasm or impacted calculi. To address this, comprehensive preoperative evaluation, effective preventive measures, and prompt intraoperative management are essential to reducing the risk of complications. This review aims to clarify ureteroscopic impaction causes, summarize prevention and management evidence, propose a new non-invasive solution and discuss its clinical value. This section examines the causes of difficult ureteroscope withdrawal secondary to intraoperative impaction. We present this article in accordance with the Narrative Review reporting checklist (available at https://tau.amegroups.com/article/view/10.21037/tau-2025-208/rc).
Methods
A systematic literature search was conducted in PubMed and Web of Science from 1999 to 2024. The search strategy employed keywords including “ureteroscopy”, “difficult ureteroscope withdrawal”, “ureteroscopic impaction”, “ureteral stricture”, “ureteroscopic complications” and “ureteral injury” combined with Boolean operators. Detailed search parameters (databases, timeframe, terms, inclusion/exclusion criteria) are summarized in Tables 1,2.
Table 1. The search strategy summary.
| Items | Specification |
|---|---|
| Date of search | December 31, 2024 |
| Databases and other sources searched | PubMed, Web of Science |
| Search terms used | Ureteroscopy, difficut ureteroscope withdrawal, ureteroscopic impaction, ureteral stricture, ureteroscopic comlications and ureteral injury |
| Timeframe | 1999 to 2024 |
| Inclusion criteria and exclusion criteria | Inclusion criteria: retrospective studies, case reports, experimental studies; Chinese and English literature; the full text is available. Exclusion criteria: non-original research (e.g., reviews, editorials) |
| Selection process | Literature screening was performed independently by H.T. and F.Y., and consensus was reached through discussion in case of divergence |
Table 2. Detailed search strategy for PubMed and Web of Science.
| Search selection | Search terms and strategy |
|---|---|
| Selection 1 | “Ureteroscope” OR “Ureteroscopic” AND “Impaction” |
| Selection 2 | “Ureteroscope” OR “Ureteroscopic” AND “Withdrawal” |
| Selection 3 | “Ureteral injury” OR “Ureteral stricture” |
| Selection 4 | “Ureteroscopy complications” OR “Ureteroscope impaction” |
Two investigators (H.T. and F.Y.) independently screened titles/abstracts of retrieved articles. Full texts of eligible studies—retrospective analyses, case reports, and experimental studies in English or Chinese—were assessed. Discrepancies were resolved through consensus. Non-original research (e.g., reviews, editorials) was excluded.
Causes of difficulty in ureteroscope withdrawal due to impaction during ureteroscopy
Operator and procedural factors
Operator inexperience and improper handling are major contributors to ureteroscope impaction (6,7). For instance, scholars have identified inadequate operator experience as a substantial risk factor for urethral injury during cesarean section procedures. The ureter’s narrow, elongated lumen and thin walls, often complicated by physiological or pathological strictures and scarring, make selecting an appropriately sized ureteroscope crucial. The limited field of view offered by the ureteroscope necessitates careful, precise, and patient manipulation. Inexperienced operators may apply excessive axial force during scope manipulation, increasing mucosal friction and edema, as demonstrated in biomechanical study (8). When this edema becomes severe, it can result in ureteroscope impaction, further complicating the procedure.
Instrument-related factors
According to published research, thin rigid ureteroscopes and pediatric ureteroscopes cause less ureteral damage compared to thicker rigid ureteroscopes, allowing for easier insertion and withdrawal with fewer postoperative complications (9-11). This evidence indicates that larger-caliber ureteroscopes are associated with elevated iatrogenic complication rates. In a comparative analysis of 4.5–6.5 Fr (French) versus 8.5–11.5 Fr semi-rigid ureteroscopes (S-URS), Atis et al. demonstrated that the 4.5–6.5 Fr S-URS cohort exhibited a significantly lower incidence of ureteral mucosal injury and postoperative hematuria compared to the larger-diameter group. These findings substantiate the clinical advantage of smaller-caliber ureteroscopes in minimizing procedure-related morbidity and enhancing postoperative recovery outcomes (12). Ureteroscopes are slender instruments comprising optical fibers and related components, initially designed primarily for diagnosing ureteral stones. They are classified into rigid and flexible types. Rigid ureteroscopes are smaller in diameter, typically ranging from 6.0 to 9.8 Fr, with a length of approximately 35–45 cm, including pediatric versions (4.5/6.0 Fr) (13). The rigid ureteroscope features a non-flexible, tapered design with a narrow front and wider rear. The distal end is equipped with a sheath lip, making it generally suitable for ureteral examination and lithotripsy in the mid and lower ureter. They are commonly used for ureteral examinations and the fragmentation of stones in the mid to lower ureter. It is important to highlight that the diameter of the rigid ureteroscope correlates closely with the risk of ureteral injury, underscoring the importance of selecting an appropriately sized instrument to minimize complications (14).
In contrast, flexible ureteroscopes feature a softer shaft and a bendable tip, making them ideal for exploring the renal collecting system and addressing stones in the renal pelvis or upper ureter. Flexible ureteroscopes are further subdivided into fiberoptic and electronic types, with the latter being more commonly used in clinical practice. While rigid ureteroscopes are effective for managing mid to lower ureteral stones, repeated insertion can increase friction against the ureteral wall, potentially causing mucosal edema (15). Their tapered design also raises the likelihood of becoming lodged in narrow segments of the ureter, complicating withdrawal (16). Flexible ureteroscopes, often paired with a flexible sheath, mitigate this friction. However, prolonged sheath pressure can still lead to mucosal edema, making device removal challenging. Therefore, choosing the appropriate type and size of ureteroscope is essential for minimizing procedural complications (17).
Anatomical constrictions of the ureter
As previously mentioned, the fundamental cause of difficult ureteroscope withdrawal is the ureteral diameter being smaller than the ureteroscope diameter for various reasons (such as the anatomical constrictions), resulting in the ureteroscope being trapped. The ureter contains three key physiological constrictions, including the ureteropelvic junction (UPJ; diameter approximately 2 mm), the point where the ureter crosses the iliac vessels (about 3 mm), and the intramural segment within the bladder wall (approximately 1–2 mm) (18). The muscular layer of the proximal ureter at the UPJ is frequently hypoplastic, predisposing to luminal stenosis or structural deformity. These anatomical alterations may significantly impair flexible ureteroscope advancement during retrograde access. In addition, the inner part of the bladder wall is the narrowest, making it a frequent site for rigid ureteroscope impaction. The proximal ureter exhibits the highest compliance, whereas the distal ureter shows reduced compliance. Age-related remodeling of the ureteral wall further alters its mechanical properties (19). Moreover, the mechanical characteristics of human ureters, demonstrating that ureteral tissue is stiffer longitudinally compared to circumferentially (20). This difference is attributed to the alignment of collagen fibers along the axial direction, which provides structural support but limits flexibility.
Pathological strictures
Iatrogenic injury is responsible for approximately 75% of ureteral strictures (2). The remaining cases are attributed to congenital abnormalities or malignancies. Published data indicate that the incidence of ureteral strictures following ureterolithotomy ranges from 0.2% to 24% (21). Persistent pressure exerted by ureteral stones can lead to localized ischemia of the ureteral wall, triggering inflammatory changes, mucosal congestion, and edema. These pathological processes may eventually result in granuloma formation and scar tissue development, culminating in luminal narrowing. Researchers identified that edematous and villous changes associated with stone impaction lead to ureteral mucosal edema and fibrosis, further contributing to stricture formation (22). Moreover, intraoperative mucosal injury, compounded by postoperative exposure to urine and inflammatory mediators at the injury site, accelerates scar formation and exacerbates luminal narrowing (23).
Ureteral spasm
Ureteral spasm is a complex phenomenon with multifactorial causes during ureteroscopy. It is influenced by factors such as anesthesia, intraoperative manipulation, and associated pathological conditions.
Anesthesia
A single-center retrospective study indicates that surgeons may prefer general anesthesia over regional anesthesia to minimize the risk of ureteral trauma (24). Ureteroscopy can be performed under various anesthetic techniques, including local, combined spinal-epidural, and general anesthesia. Achieving adequate anesthetic blockade, extending from the T8 thoracic spinal nerves to the sacral plexus, is essential (25). The choice of anesthesia is particularly critical for elderly patients. Local anesthesia, administered via infiltration, has minimal impact on cardiopulmonary function and facilitates quicker postoperative gastrointestinal recovery (26). However, its limited analgesic efficacy often results in heightened pain during prolonged procedures, increasing the risk of ureteral spasm and scope impaction. Consequently, local anesthesia is rarely employed in ureteroscopy. Combined spinal-epidural and general anesthesia provide superior anesthetic coverage and analgesia. While combined spinal-epidural anesthesia allows patients to remain conscious, inadvertent movements may risk ureteral or urethral injuries (27). General anesthesia, by inducing loss of consciousness, mitigates these risks and is therefore the preferred option in most clinical settings (28,29).
Intraoperative factors
Excessive force or repetitive scope manipulation may induce mucosal edema, triggering ureteral spasm and increasing impaction risk. Holmium laser lithotripsy, used to fragment calculi, generates significant heat via an yttrium-aluminum-garnet medium (30-32). Prolonged laser activation elevates local temperatures beyond 43 ℃, causing cytotoxic damage to adjacent tissues (33). Using low-temperature irrigation fluid can help mitigate heat-related tissue damage (34), but may irritate the ureter, provoking spasms and further complicating the procedure. Therefore, selecting an optimal irrigation temperature is crucial to balance the prevention of thermal injury with reduced ureteral irritation (35).
Pathological contributions
Urinary calculi, obstruction, and ureteral reflux frequently coexist with urinary tract infections, which contribute to ureteral wall edema, mucosal damage, and fibrosis. These changes reduce the elasticity of ureteral smooth muscle, further increasing the risk of ureteroscope impaction (36,37).
Prevention strategies for ureteroscopic impaction during ureteroscopy withdrawal
Preoperative preparation and intraoperative management strategies
A thorough preoperative evaluation should be conducted to assess for ureteral strictures or obstructions, including renal ultrasound, computed tomography (CT) urography, magnetic resonance imaging (MRI), and retrograde urethrography as appropriate (38,39). Based on the evaluation, a well-defined surgical plan should be made to reduce the risk of intraoperative complications (40). In cases of severe preoperative infection, antibiotic therapy should be initiated, and placement of a ureteral stent via cystoscopy in the affected upper urinary tract should be considered. Surgery should proceed only after effective infection control has been achieved.
During the operation, careful handling of instruments is essential to avoid excessive force and maintain a clear surgical field, with strict avoidance of blind maneuvers. If significant ureteral wall edema or mucosal injury is observed intraoperatively, placing a ureteral stent may be necessary. This measure helps facilitate urine drainage and preserve renal function, enabling further surgical intervention after the edema subsides.
Management strategies and techniques for difficult ureteroscope withdrawal during ureteral stricture
During procedures, if a ureteroscope becomes impacted, it is crucial to remain calm and avoid forceful withdrawal, as this may result in serious complications such as full-thickness ureteral tear, mucosal laceration, perforation, or rupture (41). Initially, consider transient ureteral spasm; maintain the position of the ureteroscope and wait for 10 to 30 minutes for the spasm to resolve spontaneously before gently rotating the ureteroscope for withdrawal until successful (42). If this approach fails, consider administering additional muscle relaxants to facilitate smooth muscle relaxation. If withdrawal remains challenging and resistance is significant, observe the view of the endoscopic. If the ureteroscope exhibits “reverse” motion relative to the ureter, it indicates that smooth muscle fiber tension has not reached its limit, allowing for gentle rotation and withdrawal. Conversely, if resistance is pronounced and the ureteroscope shows “co-linear” movement with a stable image, this suggests that smooth muscle fiber tension has reached its maximum, and forceful withdrawal should be avoided. We propose that when the tension of the ureteral smooth muscle fibers reaches its limit, a phenomenon known as “ureteroscope locking” occurs. In cases of ureteroscope locking, our recommended approach for females involves using the index and middle fingers to apply firm pressure on the ureteroscope wall at the urethral orifice via the vaginal canal. For males experiencing similar locking, the same technique can be applied through the rectum. Increased force may then be used to withdraw the ureteroscope until successful removal is achieved. During this process, it remains essential to observe the “reverse” and “co-linear” movement phenomena to prevent serious complications such as ureteral dislodgment or tearing. If these methods prove ineffective for ureteroscope removal, ureterotomy may be required to extract the scope and resolve the impaction (Figure 1).
Figure 1.
Flowchart for the management of difficult ureteroscope withdrawal secondary to ureteroscopic impaction. Lower ureter: apply transvaginal/transrectal counter-pressure; mid/upper ureter: proceed to ureterotomy.
In clinical practice, standard management for difficulties in withdrawing a ureteroscope due to impaction typically involves waiting for 10 to 30 minutes before attempting retraction, administering muscle relaxants to alleviate smooth muscle tension in the ureter, or performing ureterotomy for retrieval. The first two methods are effective for common instances of ureteroscope impaction, such as transient ureteral spasm or when the tension in the ureteral wall fibers has not reached its limit. However, these approaches are ineffective for cases where the tension has reached its maximum, resulting in a “stuck” phenomenon. In such instances, ureterotomy becomes necessary to resolve the impaction. Nonetheless, ureterotomy is an invasive procedure that increases patient trauma, discomfort, hospital stay, and economic burden, and may lead to postoperative complications such as ureteral stricture. Through clinical observation and reflection, we have successfully developed and applied a method for assessing and addressing the “stuck” phenomenon of the ureteroscope. When significant resistance is felt during ureteroscope withdrawal, the endoscopic view may show synchronous motion between the ureteroscope and the ureteral wall, indicating a potential “stuck” phenomenon. In cases where this occurs, for female patients, the surgeon may apply counter-pressure transvaginally using the index and middle fingers to firmly secure the urethral orifice of the ureteroscope, for males, transrectal counter-pressure may be utilized. This technique prevents outward movement of the ureter wall with the ureteroscope, thereby mitigating the risk of ureteral detachment and serious complications such as laceration. This method effectively addresses the impaction in most cases. If withdrawal remains challenging, this approach can still be employed. Should this method prove ineffective, ureterotomy for retrieval is the only option. Compared to ureterotomy, this technique significantly reduces patient discomfort, hospital stay duration, and associated costs, while also avoiding severe complications. This method is primarily effective for stuck phenomena occurring in the lower ureter; it is contraindicated for mid or upper ureteral issues, where ureterotomy should be employed to prevent excessive traction that could lead to laceration or even complete rupture of the ureter.
The theoretical basis for the feasibility of this method can be summarized as follows: (I) the distance from the urethral orifice to the ureteral orifice has been reported to be approximately 22.89±10.59 mm for the left ureter and 24.88±10.86 mm for the right ureter, with an average distance of 27.21±11.11 mm between the two ureteral orifices, which is not necessarily correlated with height. (II) The ureter exhibits a certain degree of extensibility as it is a muscular duct located in the retroperitoneal space, characterized by a complex multilayered structure. Ureteral peristalsis results from the coordinated mechanical activity of circular and longitudinal smooth muscle layers, with the longitudinal layer playing a predominant role (43). The ureter extends approximately 20–30 cm from the kidney to the bladder and possesses stretchability within certain limits. One study indicated that the circumferential and longitudinal tensile strengths of the ureter are approximately 457.52±33.74 and 902.43±122.08 Ncm², respectively (8). Therefore, the proposed treatment strategy is theoretically effective and has demonstrated significant efficacy based on our clinical practice involving several cases.
Discussion
This review examines the complication of ureteroscopic impaction in depth. Studies have found that the main causes of ureteroscopic impaction include operator factors, instrumental factors, anatomical ureteral stricture, pathological stricture, and ureteral spasm. In terms of prevention, adequate preoperative evaluation, appropriate ureter selection, and delicate manipulation techniques are key strategies. In terms of management, mild impaction can be resolved by watchful waiting, while severe impaction requires specialized exit techniques.
The research covers many aspects of ureteroscopic impaction, including its causes, preventive measures, and treatment strategies, and provides comprehensive guidance for clinicians. However, there are still some limitations to the existing research. On the one hand, the sample size of some studies is small, which may affect the reliability and generalizability of the results. On the other hand, there are differences in study design, evaluation methods, etc., which may also affect the comparability of results.
Future research should focus on optimizing relevant technologies and methods to further improve the safety and efficacy of ureteroscopy. For example, multicenter, prospective studies can be conducted to more accurately assess the actual effects of various prevention and management strategies. At the same time, strengthen the research and development and evaluation of new ureteroscopy devices to provide more and better choices for clinicians. In addition, the molecular mechanism and pathophysiological process of ureteroscopic impaction need to be deeply explored, so as to provide a theoretical basis for the development of more effective prevention and treatment methods.
Conclusions
This review provides clinicians with a comprehensive strategy for the prevention and management of ureteroscopic impaction that can help reduce surgical risk and improve patient outcomes. In clinical practice, doctors should be fully aware of the potential risks of ureteroscopic impaction and take corresponding preventive and management measures before, during, and after surgery. For policymakers, research should be encouraged and supported to improve the quality of care and patient safety. Future research should focus on how to optimize existing technologies and methods, develop new prevention and treatment strategies, and strengthen the basic research on the mechanism of ureteroscopic impaction, so as to provide a more solid scientific basis for clinical practice.
Supplementary
The article’s supplementary files as
Acknowledgments
None.
Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.
Footnotes
Reporting Checklist: The authors have completed the Narrative Review reporting checklist. Available at https://tau.amegroups.com/article/view/10.21037/tau-2025-208/rc
Funding: This work was supported by the National Natural Science Foundation of China (No. 82260141) and the Chinese Medicine Science and Technology Project of Jiangxi Province (No. 2023B1229).
Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://tau.amegroups.com/article/view/10.21037/tau-2025-208/coif). The authors have no conflicts of interest to declare.
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