Robot-assisted ureteral reconstruction using buccal mucosal graft for traumatic complete ureteral avulsion: a rare case report

Introduction

Blunt ureteral trauma remains relatively rare, constituting less than 1% of all urological injuries (1,2), owing to the ureter’s small size, inherent mobility, and protection afforded by surrounding anatomical structures. Traffic accidents represent the predominant cause of blunt ureteral trauma (3). Clinicians should maintain a high index of suspicion for ureteric injury in blunt trauma cases involving deceleration mechanisms, as these frequently result in renal pelvic avulsion from the ureter, particularly affecting the upper ureteral segment (4). The American Association for the Surgery of Trauma-Organ Injury Scale classifies ureteral injuries into five grades according to laceration severity and avulsion extent, with complete tears demonstrating >2 cm separation representing the most severe grade (5).

Management strategies for traumatic ureteral injuries depend upon multiple factors, including etiology, anatomical location, timing of diagnosis, and injury severity (6). For cases presenting with mild ureteral injury, initial management typically involves nephrostomy tube or ureteral stent placement, with subsequent endourological intervention or ureteral reconstruction reserved for patients who develop ureteral strictures. Complete ureteral avulsion necessitates immediate reconstructive surgery, as the absence of hydronephrosis complicates nephrostomy tube insertion and precludes delayed sequential repair. Available reconstructive options encompass ureteroureterostomy, ureterocalycostomy, ureteral reimplantation, and reconstruction utilizing bowel segments or graft materials (4).

Traditionally, open or laparoscopic reconstructive techniques have been employed to manage complex or recurrent ureteral strictures (7-9); however, these approaches have inherent limitations, including increased postoperative pain, extended hospital stays, and prolonged recovery periods (10,11). Consequently, robot-assisted surgeries, including simple ureteroureterostomy, reimplantation, and reconstruction using bowel segments or grafts, have emerged as viable options with favorable outcomes, benefiting from three-dimensional vision, magnified visibility, and adjunct near-infrared fluorescence imaging (9-12). However, robot-assisted ureteral reconstruction (RAUR) using a buccal mucosal graft (BMG) for traumatic complete ureteral avulsion has been rarely reported. This study aimed to evaluate the feasibility and safety of RAUR using BMG during a 14-month follow-up period. We present this article in accordance with the CARE reporting checklist (available at https://tau.amegroups.com/article/view/10.21037/tau-2025-476/rc).

Case presentation

Patient information and preoperative preparation

An 18-year-old man with no previous medical history presented to Toyota Memorial Hospital following a head-on collision with a car while riding a motorcycle at an unknown speed. He was diagnosed with blunt abdominal injury with gross hematuria and multiple organ injuries. Whole-body computed tomography (CT) revealed a maxillary fracture (Le Fort I), mandibular fracture, bilateral pulmonary contusion, left 9th rib fracture, open fracture of the right femur, abdominal muscle injury (transverse abdominis, internal oblique, and external oblique muscles), and fluid accumulation in the left retroperitoneal area suggestive of retroperitoneal bleeding or urine leakage (Figure 1A,1B). Blood tests were as follows: hemoglobin, 14.7 g/dL; hematocrit, 43.4%; creatinine, 0.76 mg/dL; and estimated glomerular filtration rate, 114 mL/min. The patient was admitted, and surgery for the maxilla, mandible, and right femur was performed on post-injury day (PID) 9.

Figure 1 CT images after traffic injury. (A,B) CT images showed fluid accumulation in the left retroperitoneal area on the injury day. (C,D) CT images on PID 16 showed a large collection in the left retroperitoneal area. CT, computed tomography; PID, post-injury day.

On the night of PID 16, the patient’s left flank pain worsened, and CT revealed significant fluid accumulation extending from the left retroperitoneal area to the left flank (Figure 1C,1D). A 14 Fr Malecot catheter was placed as a drain in the left retroperitoneal space. Biochemical tests confirmed that the fluid was urine. The patient was transferred to Nagoya City University Hospital on PID 44. On PID 45, despite minimal hydronephrosis, an ultrasound-guided renal puncture was performed, and a 12-Fr nephrostomy tube was successfully placed. Simultaneous antegrade and retrograde ureterography (Figure 2A) and 3D CT images (Figure 2B) revealed complete ureteral avulsion with a 55-mm gap defect. The Malecot drain was removed on PID 59 (two weeks after nephrostomy placement), and the patient was scheduled for ureteral reconstruction within three months. Unfortunately, the surgery was postponed because of the coronavirus disease 2019 pandemic. Finally, RAUR with BMG was performed at post-injury month 8 after discussing all options with the patient.

Figure 2 Simultaneous antegrade and retrograde ureterography and 3D CT images. (A) Guidewire was inserted into both ends of the proximal and distal ureter. (B) CT images revealed complete ureteral avulsion with a gap defect of 55 mm. CT, computed tomography.

All procedures performed in this study were in accordance with the ethical standards of the institutional and/or national research committee(s) and with the Declaration of Helsinki and its subsequent amendments. Written informed consent was obtained from the patient for publication of this case report and accompanying images. A copy of the written consent is available for review by the editorial office of this journal.

Surgical technique

After general anesthesia with nasotracheal intubation, two Infrared Illumination System (IRIS) ureteral catheters (Stryker, Kalamazoo, MI, USA) were inserted to identify the endpoint of the separated ureter: one up to the distal end of the left ureter and the other into the proximal end via the nephrostomy tube.

Subsequently, the patient was positioned in lateral decubitus with the left side upward, and robotic surgery was initiated using the da Vinci Xi surgical system (Intuitive Surgical, Sunnyvale, CA, USA). Robotic port placement is shown in Figure 3A. Intraoperative photographs and schematic illustrations of the procedure are presented in Figure 3B-3H and Figure 4A-4D. After medial mobilization of the colon, severe adhesions were observed around the left ureter. IRIS catheters proved useful for identifying the proximal and distal ends. The distal ureter and surrounding tissues of the renal pelvis were dissected sequentially. However, due to the long distance between both ureteral ends, tension-free anastomosis was difficult. Therefore, downward nephropexy (DN), as previously described (13), was performed to provide caudal kidney mobilization, and adequate anastomosis of the separated ureters was confirmed.

Figure 3 Intraoperative images demonstrating the surgical technique. (A) Port placement. The red circle indicates the 8-mm camera port. The blue circles indicate the second, third, and additional 8-mm robotic ports. The green triangle indicates the 12-mm assistant port. (B) Identification of both ureteral ends under illumination with an IRIS catheter. The left side indicates the proximal end of the ureter, and the right side indicates the distal end. (C) Identification of both ureteral ends using an IRIS catheter with the Firefly fluorescence system. (D) Defect length measuring approximately 40 mm after debridement of all necrotic tissue. (E) Harvested BMG. (F) Dorsal-side anastomosis. (G) BMG onlay with sutures along one side. (H) Final placement of the BMG with completed continuous sutures along both sides. BMG, buccal mucosal graft; IRIS, Infrared Illumination System.

Figure 4 Schematic illustration of RAUR with BMG. (A) Identification of ureteral ends using IRIS catheter. (B) Downward nephropexy. (C) Dorsal-side anastomosis. Blue arrow indicates the side-to-side (dorsal) anastomosis site. (D) BMG onlay with sutures along one side. BMG, buccal mucosal graft; IRIS, Infrared Illumination System; RAUR, robot-assisted ureteral reconstruction.

The robotic system was undocked, and the oral maxillofacial surgery team harvested a 45×20 mm BMG from the right buccal pouch. The graft was rinsed in saline to remove blood clots and debris. Fat, muscle fibers, and submucosal tissue were meticulously removed, and the graft was kept in saline until implantation. After completing the oral procedure, the robotic system was re-docked, and the intraperitoneal procedure resumed. Ureteral segments containing pathological scar tissue were excised to expose the healthy ureter completely. The ureteral ends were spatulated anteriorly, and the dorsal ureteral wall was anastomosed using continuous running sutures with 4-0 PDS, followed by placement of a 6-Fr ureteral stent across the defect. The harvested BMG was introduced into the abdominal cavity through an accessory port and sutured to the anterior ureteral defect in an onlay fashion using 4-0 PDS. The reconstructed segments were wrapped with adjacent fat tissue to ensure blood supply and fixed to the psoas muscle with 3-0 absorbable sutures. Finally, a vacuum drain was placed near the anastomosis at the completion of the operation. Robotic console time was 422 min, and estimated blood loss was 181 mL.

Postoperative outcome

The patient’s postoperative course was uneventful. On postoperative day (POD) 10, the patient developed fever after the nephrostomy tube was clamped; therefore, the tube was unclamped. The drain was removed on POD 21. The patient remained stable and was discharged on POD 27. The nephrostomy tube was removed 10 weeks postoperatively after antegrade pyelography confirmed the absence of urinary leakage from the reconstructed segments. The ureteric stent was removed at 17 weeks postoperatively. The patient remained in good condition, and a mercaptoacetyl triglycine (MAG3) renal scan at 9 months postoperatively demonstrated split function of 53% in the left kidney and 47% in the right kidney, without evidence of obstruction in either kidney (Figure 5A). At the 14-month follow-up, no hydronephrosis was detected on the left side by ultrasonography or CT (Figure 5B).

Figure 5 MAG3 scintigraphy and 3D CT imaging. (A) MAG3 renal scan at 9 months postoperatively demonstrating good split function in both kidneys without evidence of obstruction. (B) 3D CT urography at 14-month follow-up. CT, computed tomography.

Discussion

Blunt ureteral trauma often occurs together with multiple organ injuries, which may delay diagnosis and treatment because other symptoms are often more concerning (14). The treatment choice for ureteric injury depends on the cause, mechanism, timing, location, and severity of the injury (14). Immediate repair is usually recommended (4,6), especially in cases of complete avulsion due to difficulty in ureteral stent or nephrostomy insertion; however, damage control with delayed definitive repair is preferred in multiple organ injuries and unstable patients (6,15). Here, the patient’s general condition was stable when he was transferred to our hospital. However, delayed definitive reconstruction was chosen to optimize both the local tissue environment and the patient’s overall condition. From a wound-healing perspective, delayed surgery allows the acute inflammatory phase to subside and the transition to the proliferative and remodeling phases to occur, leading to reduced tissue edema, clearer anatomical planes, and more robust granulation tissue (16). These factors may minimize the risk of intraoperative bleeding and facilitate safe dissection and graft incorporation. Moreover, delayed repair allows surrounding adhesions to mature, thereby contributing to a more accurate identification of the boundary between normal and abnormal ureteral tissues. The interval also allowed the patient to recover from multiple injuries, reduce the systemic inflammatory response, and improve their nutritional and respiratory status, which are crucial for optimal healing and reduced postoperative complications. In this stable setting, the RAUR with BMG can be performed more safely and effectively, underscoring the value of a carefully timed staged approach in complex trauma cases.

As injured tissues are replaced by rigid anatomies or fibrosis through extracellular matrix accumulation (17), the ureteral ends in delayed definitive cases are often surrounded by dense scar tissue, complicating identification. In this case, we employed IRIS catheters via both antegrade and retrograde access, enabling precise visualization of the proximal and distal ureteral ends and serving as critical landmarks during robotic dissection. The IRIS is a recently introduced device that facilitates ureter identification during laparoscopic and robotic colorectal surgeries (18). We previously reported that IRIS use offers significant advantages in RAUR, particularly in cases complicated by severe adhesions and anatomical challenges (19). This technique minimized tissue disruption and ensures anastomosis between healthy ureteral segments, thereby reducing the risk of stricture or ischemia.

Various options exist for treating upper ureteric injuries, including ureteroureterostomy, transuretero-ureterostomy, ureterocalycostomy, and ureterocystostomy (20,21). Ureteral defects following trauma with urine leakage are typically surrounded by nonviable tissue, scarring, and fibrosis, resulting in longer gap defects after dissection and debridement of unhealthy tissue, thus complicating reconstruction. In our case, the gap between both ureteral ends after debridement measured 55 mm, prompting us to perform DN combined with onlay BMG to address this defect. Lee et al. reported that DN can provide approximately 3–5 cm of caudal renal mobilization (22). After caudal nephropexy, the dorsal wall of the ureter was mobilized sufficiently to allow approximation without significant tension. However, attempting a complete circumferential end-to-end anastomosis would have resulted in excessive tension along the ureter. Therefore, a BMG was applied to augment the anterior aspect, which reduced overall anastomotic tension and minimized the risk of circumferential scarring and subsequent stricture formation. BMG and lingual mucosal grafts have gained wider acceptance for ureteral reconstruction due to their low complication rates and favorable medium-term outcomes in complex ureteral strictures (23-25). The use of BMGs has long been established, particularly in urethroplasty, owing to their ease of harvesting, favorable elasticity, and excellent capacity to receive vascular supply from surrounding tissues (26). The harvested BMG was sutured as an anterior onlay patch over the ureteral defect. This approach maintained luminal patency without requiring bowel interposition, and the mucosal compatibility of the BMG likely facilitated urothelial regeneration. Onlay flap or graft ureteroplasty is widely used and marked as safe and feasible to repair long and complex ureteral strictures, with high efficiency and good outcomes (27).

A key step in ureteroplasy involves suturing well-vascularized tissues, such as the omentum, around the reconstructed ureter (9,24). However, Jiang et al. reported that wrapping with perinephric fat not only prevents the potential effects of using omentum on abdominal organs but is as safe and effective as the omentum wrapping technique in ureteral reconstruction using a BMG (28). In this case, the reconstructed segments were wrapped with adjacent fat tissue instead of omentum wrapping and fixed to the psoas muscle, which may contribute to the adequate blood supply.

To the best of our knowledge, this study is one of the few studies describing complete ureteric avulsion from blunt abdominal trauma successfully managed with RAUR using a BMG. The success of this treatment can be attributed to three factors. First, nephrostomy placement enabled delayed definitive surgery with resolution of inflammation. Second, the IRIS catheter proved valuable in accurately identifying ureteral ends within adhesive tissue. Third, DN and BMG onlay contributed to achieving tension-free anastomosis. Furthermore, the use of the robotic system facilitated a minimally invasive approach, contributing to improved patient comfort and recovery.

This reports describes the successful management of a delayed definitive repair of a left ureteral avulsion due to blunt abdominal trauma using RAUR with BMG, resulting in minimal complications and preserved renal function at 14-month follow-up. However, there are still few reports on using a BMG for ureteric reconstruction in trauma patients; more studies and longer follow-ups are needed to find out the results, complications and limitations of this method.

Conclusions

This case (with a 14-month follow-up period) demonstrates that RAUR using a BMG may be a feasible, safe, and minimally invasive option for managing complete ureteral avulsion in selected trauma cases. The success of this approach depends on careful preoperative planning, optimal surgical timing to allow tissue conditioning, intraoperative guidance with IRIS catheters, and adjunct techniques such as nephropexy and mucosal grafting to achieve tension-free repair. As robotic platforms become increasingly accessible, this strategy may provide a reproducible and effective alternative to open reconstruction for complex ureteral injuries. Further studies are warranted to validate long-term outcomes and define the role of this technique within the reconstructive urologic armamentarium.

Acknowledgments

We thank the patient for his participation in this report.

Footnote

Reporting Checklist: The authors have completed the CARE reporting checklist. Available at https://tau.amegroups.com/article/view/10.21037/tau-2025-476/rc

Peer Review File: Available at https://tau.amegroups.com/article/view/10.21037/tau-2025-476/prf

Funding: None.

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://tau.amegroups.com/article/view/10.21037/tau-2025-476/coif). C.B. receives support for attending the JUA meeting 2024 from Mega Lifescience Public Company Limited, Thailand. Shuzo Hamamoto receives payment for lectures from Boston Scientific, Olympus, Johnson & Johnson and Eisai; consulting fees from Nipro; and grants from Daiwa Securities Foundation and The Japanese Foundation For Research and Promotion of Endoscopy. The other authors have no conflicts of interest to declare.

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. All procedures performed in this study were in accordance with the ethical standards of the institutional and/or national research committee(s) and with the Declaration of Helsinki and its subsequent amendments. Written informed consent was obtained from the patient for publication of this case report and accompanying images. A copy of the written consent is available for review by the editorial office of this journal.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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