Robotic tubular pyeloureteroplasty using flap and lingual mucosal graft: a case report and literature review

Introduction

Ureteropelvic junction obstruction (UPJO) is a prevalent urological condition that can arise from various factors, including vascular compression or the formation of calculi (1). The Anderson-Hynes pyeloplasty remains the standard surgical approach for UPJO, demonstrating a high success rate exceeding 90% in adult patients (2). However, initial surgical intervention for UPJO may lead to recurrent obstruction due to factors such as scar tissue formation and fibrosis, crossing vessels, or technical failures (3-5). Pyeloplasty is generally indicated for patients with localized UPJO, preserved renal function, and no significant anatomical distortion (6). Recurrent UPJO complicated by long-segment obliterative strictures, extensive periureteral fibrosis, aberrant vascular anatomy, or severe renal atrophy presents substantial challenges to native ureteral reconstruction, complicating the execution of conventional pyeloplasty (6).

Flap pyeloplasty reconstructs the ureteropelvic junction (UPJ) by utilizing the enlarged renal pelvis, ensuring adequate blood supply and a tension-free anastomosis (7). However, in cases where UPJO is associated with long proximal ureteral obliteration, the dilated renal pelvis may be insufficient for effective reconstruction. In cases of long-segment proximal ureteral strictures or obliteration, the traditional treatment options for recurrent UPJO include renal autotransplantation and ileal ureteral replacement, which are frequently associated with a high incidence of long-term complications, particularly those related to bowel substitution and vascular anastomosis (8-10). In recent years, many urologists have increasingly turned to oral mucosal graft, such as buccal mucosal graft (BMG) and lingual mucosal grafts (LMGs), to aid in the management of complex proximal ureteral strictures (11,12). Our previous studies have demonstrated that lingual mucosal graft ureteroplasty (LMGU) is both safe and effective for reconstructing long proximal ureteral strictures, and it has successfully repaired strictures up to 11.5 cm in length (12,13).

Herein, we present a novel, minimally invasive technique: robotic tubular pyeloureteroplasty using flap and LMG for selected patients with recurrent UPJO. This article summarizes the details of the technique and reports our initial experience. We present this article in accordance with the CARE reporting checklist (available at https://tau.amegroups.com/article/view/10.21037/tau-2025-646/rc).

Case presentation

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 the 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. A 38-year-old male was diagnosed with right-sided UPJO during a routine physical examination, with computed tomography (CT) imaging confirming the diagnosis, without any symptoms. The patient had a history of hyperuricemia and, despite being classified as American Society of Anesthesiology (ASA) class II preoperatively, did not have comorbidities such as diabetes, hypertension, or chronic kidney disease. He underwent an initial Anderson-Hynes pyeloplasty at another medical center due to progressively worsening hydronephrosis detected during a routine examination, along with renal function impairment. A Double-J stent was inserted and removed after six weeks. However, follow-up examinations three months later revealed recurrent stricture and severe hydronephrosis. One month before the second reconstructive surgery, our center performed percutaneous nephrostomy to ensure ureteral rest and protect renal function (14). Preoperative CT urography showed right-sided UPJO with tissue adhesions and moderate hydronephrosis (Figure 1A). Postoperative CT urography demonstrated patency of the right ureter and marked improvement in hydronephrosis (Figure 1B). Antegrade and retrograde urography revealed a right-sided proximal ureteral stricture with an approximately 3.0 cm stricture at the L3 level (Figure 1C). At eight weeks post-surgery, urography revealed a reconstructed ureteral segment that was free from obstruction (Figure 1D).

Figure 1 Imaging findings prior to and following surgical intervention. (A) One-month post-nephrostomy, CT urography demonstrated moderate right renal hydronephrosis (red arrow). (B) CT urography conducted 16 months post-surgery revealed mild right renal hydronephrosis (red arrow). (C) Antegrade and retrograde urography revealed right-sided proximal ureteral stricture with an approximately 3.0 cm stricture at the L3 level (yellow arrow). (D) At 8 weeks postoperatively, antegrade urography revealed no obstruction in the reconstructed ureter segment (yellow arrow). CT, computed tomography.

At the start of the procedure, the nephrostomy tube was clamped, causing dilation of the renal pelvis. After inducing general anesthesia via nasotracheal intubation, the patient was positioned in the left lateral decubitus position at 70°, with the waist elevated. Port placement was performed as described in previous reports (13). The lateral peritoneum was incised along the colon to mobilize the ascending colon towards the midline. Careful dissection separated the diseased ureter and enlarged renal pelvis from surrounding fibrous tissue. The diagnosis of right-sided UPJO was confirmed, with renal pelvis dilation (Figure 2A).

Figure 2 Intraoperative steps of surgery. (A) Approximately 3.0 cm of right-sided UPJO with renal pelvic dilation. (B) The atretic ureteral segment was resected, preserving the dorsal adventitia, and the renal pelvis was mobilized to align with the normal-caliber ureter for suturing. (C) A 3.0 cm × 1.5 cm flap was harvested, flipped, and inverted, then sutured to the posterior ureteral incision after longitudinal dissection of the ventral ureter for approximately 0.8 cm. (D) A 5 Fr Double-J stent was inserted across the ureteral defect. (E) A 3.8 cm × 1.5 cm lingual mucosal graft was harvested and sutured at both ends to the ventral ureteral and renal pelvic incisions, with continuous suturing along the middle portion. (F) The repaired ureter is covered with omentum. UPJO, ureteropelvic junction obstruction.

During the resection of the atretic segment of the ureter, meticulous care was taken to preserve its dorsal adventitia. This was done while mobilizing the renal pelvis to ensure proper alignment with the surrounding normal-caliber ureteral tissue for subsequent suturing (Figure 2B). We performed an incision in the ureter and utilized a 10 Fr catheter to investigate both the proximal and distal ends of the ureteral stricture, continuing until the catheter could traverse the ureter without encountering resistance. Additionally, a 5 Fr calibrated catheter was used to measure the distance from the designated base to the inferior corner of the ureterotomy, ensuring accurate flap length determination. A flap measuring 3.0 cm in length and 1.5 cm in width was harvested, flipped, and inverted. The normal ureter was then longitudinally dissected from the ventral side for approximately 0.8 cm. The flap was intermittently sutured to the posterior ureteral incision using 5-0 Monocryl sutures, achieving posterior ureteral reconstruction (Figure 2C). Finally, a 5 Fr Double-J stent was inserted through the newly formed ureteral defect (Figure 2D). Details regarding the harvesting procedures for LMG are outlined in our previous publication (4). An LMG, measuring approximately 3.8 cm in length and 1.5 cm in width, was positioned ventrally to the defective ureter. The LMG was secured using 5-0 Monocryl sutures, with both ends first attached to the ventral incision of the ureter and the renal pelvic incision. Subsequently, the middle portion of the flap and LMG were sutured consecutively to facilitate tubularization (Figure 2E). The reconstructed ureteral segment was covered with an omental flap to ensure adequate blood supply (Figure 2F). Finally, a drainage tube was placed into the pararenal space before closing all incisions in multiple layers. A schematic diagram of the surgical model is presented in Figure 3.

Figure 3 Schematic diagram of the surgical model. (A,B) Resection of ureteral obliteration. (C,D) A flap is harvested, flipped and inverted, then sutured to the dorsal ureteral incision. (E) A lingual mucosal graft is harvested and sutured at both ends to the ventral ureteral and renal pelvic incisions, with continuous suturing along the middle. (F) The repaired ureter is covered with omentum.

The surgery was successfully conducted on the robotic platform without intraoperative complications. The surgical time was 220 minutes, with an intraoperative blood loss of 50 mL. Postoperatively, the patient experienced slurred speech for three days but could eat normally by day five. Two weeks following the surgery, the donor site exhibited no pain, and tongue mobility and dietary intake were satisfactory. The drainage tube was removed on postoperative day four, and the Double-J stent was removed 6 weeks later. At eight weeks postoperatively, the nephrostomy tube was removed. Ultrasound imaging indicated a significant reduction in hydronephrosis three months after surgery. During follow-up assessments, the patient reported no lower back discomfort after surgery. By sixteen months postoperatively, the glomerular filtration rate of the right renal increased from 25.03 to 28.03 mL/min, while split renal function improved from 33.00% to 37.56%.

Discussion

UPJO is a condition caused by various factors that obstruct urine flow from the renal pelvis to the ureter. While Anderson-Hynes pyeloplasty has a success rate exceeding 90%, surgical failure still occurs relatively frequently (2,15). Factors contributing to these failures include inadequate blood supply to ureteral tissues, urine extravasation leading to inflammatory fibrosis, unaddressed crossing vessels, and complex strictures or infections (3-5). Consequently, recurrent UPJO presents significant pathophysiological challenges for management.

Current evidence indicates that endoscopic management does not offer comparable success rates when compared to open, laparoscopic, or robot-assisted pyeloplasty as primary treatments (16). Studies have shown that robot-assisted pyeloplasty is safe and effective in recurrent UPJO, offering advantages such as magnification, three-dimensional visualization, smaller incisions, and precise suturing (17).

Recurrent UPJO with long proximal ureteral obliteration poses a significant clinical challenge. In revision surgeries, scar tissue from previous surgeries often complicates repair success (6). High tension at the anastomosis site further diminishes the effectiveness of traditional pyeloplasty and may even contraindicate the procedure in some cases. Conventional surgical options for long-segment proximal ureteral strictures or obliteration include ileal ureteral replacement and renal autotransplantation. However, their use is often limited due to potentially severe complications, including gastrointestinal issues (such as mucous secretion, absorption of metabolites from ileal mucosa, and the large cross-sectional diameter of the ileal lumen) and vascular complications (8-10). Previous research has shown that ureterocalicostomy is a safe and feasible option for patients with recurrent UPJO, particularly in cases where the renal pelvis is intrarenal, severely scarred, or too small to permit tension-free anastomosis (18). However, the patient in this case did not fully meet the criteria for this surgical approach. A promising alternative for urinary tract reconstruction involves utilizing the enlarged renal pelvis and urothelium, which has gained attention recently. The non-dismembered flap pyeloplasty technique incorporates the fibrotic, peristaltically impaired segment into the reconstructed ureter but presents challenges, especially with atrophic ureters. Conversely, dismembered repair remains widely used and can be adapted to most UPJs. Dismembered flap pyeloplasty requires complete excision of the fibrotic segment and replaces it with a tubular flap (19). However, the effectiveness of this method is limited by the width of the flap used to determine UPJ diameter, potentially leading to a narrower ureter.

In recent years, several studies have confirmed the feasibility and efficacy of oral mucosal graft pyeloplasty compared to traditional pyeloplasty in the treatment of recurrent UPJO, particularly in cases of long-segment ureteral strictures, dense periureteral fibrosis, or complete obliteration of the ureteral lumen, as well as when local tissue is insufficient for a tension-free primary anastomosis (11,12). The choice between BMG and LMG for grafting remains controversial. Lumen et al. found that complications following LMG harvesting, such as difficulty opening the mouth and persistent numbness, were significantly fewer than those after BMG harvesting (20). Patients who smoke or chew betel quid often have poor oral hygiene, which can compromise the quality of the BMG (21,22). For patients with longer strictures, LMG can replace BMG for graft reconstruction (23). The benefits of LMG include their constant availability, ease of harvesting, strong infection resistance, and favorable tissue properties such as thick epithelium, thin lamina propria, good elasticity, resilience, and rich vascularization (24). Our team’s research confirms that LMGU is a safe, feasible, and effective long-term method for managing long proximal ureteral strictures (12). Table 1 presents a summary of the literature on non-dismembered flap pyeloplasty and LMGU.

The arterial plexus in the adventitia of the ureter gives rise to branches that form a finer network in the submucosa, from which capillaries drain into a venous plexus that re-enters the adventitia, following the arterial pathways (33). During surgery, a non-dismembered, vascularized renal pelvis flap with a length-to-width ratio of less than 3:1, along with preservation of the ureteral adventitia, is essential for maintaining blood supply, and the omentum is used to provide a vascular bed for the graft (27). It is imperative that the anastomosis ensures a tension-free, watertight connection that is both smooth and broad, facilitating proper alignment of the mucosa-to-mucosa interface. Nguyen et al. reported a novel technique for the treatment of complex ureteral strictures, involving the creation of a U-shaped renal pelvis flap as the posterior plate, with a BMG serving as the anterior plate (34). This technique aligns closely with our proposed approach.

In cases of long proximal ureteral obliteration, approaches typically involve excising the stenotic segment, spatulating the dorsal ureter, performing anastomosis at both ends of the dorsal ureter, and conducting onlay ureteroplasty using the LMG (12). However, in cases where LMGU is not feasible due to long stricture length or immobility of the proximal ureter resulting from infection, scarring, or fibrosis, the technique we propose offers a potential solution to achieve a sufficiently wide and long ureteral lumen.

In this study, we propose a novel technique of robotic tubular pyeloureteroplasty using a flap and LMG, where the flap forms a posterior plate and the LMG serves as the anterior plate. This technique aims to create a new, wide, and tubularized UPJ with adequate blood supply and tension-free anastomosis. Our approach combines the benefits of non-dismembered flap pyeloplasty and LMGU, making it suitable for patients with UPJO. This technique can potentially obviate the need for renal autotransplantation, ureterocalicostomy, or ileal ureteral replacement.

Based on our experience, this combined technique may be considered for UPJO patients presenting with: (I) a long stricture length or immobility of the proximal ureter, resulting from infection, scarring, or fibrosis, which causes high tension at the anastomotic site or compromised blood supply, potentially precluding pyeloplasty; (II) a long segment of proximal ureteral obliteration or obstruction, which further complicates the technical feasibility of redo pyeloplasty.

This study is based on a single case, which limits the broader applicability of the findings. Additionally, the 16-month follow-up period is relatively short, restricting long-term outcome evaluation and potential complications assessment. Furthermore, potential limitations such as graft contracture, ischemia, or concerns regarding long-term patency need to be carefully considered. Therefore, further large-scale, long-term prospective studies are needed to evaluate this novel technique.

Conclusions

Robotic tubular pyeloureteroplasty using a flap and LMG is a safe and effective surgical option, offering a promising treatment for selected patients with UPJO. This technique serves as an alternative for those with complex anatomical challenges typically encountered in pyeloplasty.

Acknowledgments

None.

Footnote

Reporting Checklist: The authors have completed the CARE reporting checklist. Available at https://tau.amegroups.com/article/view/10.21037/tau-2025-646/rc

Peer Review File: Available at https://tau.amegroups.com/article/view/10.21037/tau-2025-646/prf

Funding: This work was supported by the National Natural Science Foundation of China (grant No. 82470724); Zhongnan Hospital of Wuhan University (grant No. rcyj20230102) to B.L.; and the Institute of Urology, Wuhan University (No. ZLYNXM20200204) to C.L.

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://tau.amegroups.com/article/view/10.21037/tau-2025-646/coif). The 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 the 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/.

References

1. Khan F, Ahmed K, Lee N, et al. Management of ureteropelvic junction obstruction in adults. Nat Rev Urol 2014;11:629-38. [Crossref] [PubMed]
2. Dirie NI, Ahmed MA, Mohamed MA, et al. Robot-assisted Laparoscopic Pyeloplasty in Adults: A Comparison Analysis of Primary versus Redo Pyeloplasty in a Single Center. Urol J 2020;18:45-50. [PubMed]
3. Elsawy M, Ahmed F, Youssef M, et al. Risk Factors Influencing the Recurrence of Obstruction Post-Pediatric Pyeloplasty: A Single-Center Prospective Study. Alexandria Journal of Medicine 2024;60:131-7. [Crossref]
4. Gao W, Zhang L, He Y, et al. Analysis of the efficacy and risk factors of surgical treatment of recurrent UPJO in adults. Int Urol Nephrol 2023;55:1493-9. [Crossref] [PubMed]
5. Li J, Yang Y, Li Z, et al. Redo laparoscopic pyeloplasty for recurrent ureteropelvic junction obstruction: Propensity score matched analyses of a high-volume center. Front Pediatr 2022;10:997196. [Crossref] [PubMed]
6. Ishii D, Mori K, Shiba I, et al. Current Status and Future Perspectives of Robotic-Assisted Redo Pyeloplasty for Recurrent Ureteropelvic Junction Obstruction. Int J Urol 2025;32:1750-61. [Crossref] [PubMed]
7. Salehipour M, Khezri A, Azizi V, et al. Open dismembered tubularized flap pyeloplasty: an effective and simple operation for treatment of ureteropelvic junction obstruction. Urol Int 2006;76:345-7. [Crossref] [PubMed]
8. Cowan NG, Banerji JS, Johnston RB, et al. Renal Autotransplantation: 27-Year Experience at 2 Institutions. J Urol 2015;194:1357-61. [Crossref] [PubMed]
9. Eisenberg ML, Lee KL, Zumrutbas AE, et al. Long-term outcomes and late complications of laparoscopic nephrectomy with renal autotransplantation. J Urol 2008;179:240-3. [Crossref] [PubMed]
10. Matlaga BR, Shah OD, Hart LJ, et al. Ileal ureter substitution: a contemporary series. Urology 2003;62:998-1001. [Crossref] [PubMed]
11. Zhao LC, Weinberg AC, Lee Z, et al. Robotic Ureteral Reconstruction Using Buccal Mucosa Grafts: A Multi-institutional Experience. Eur Urol 2018;73:419-26. [Crossref] [PubMed]
12. Liang C, Wang J, Hai B, et al. Lingual Mucosal Graft Ureteroplasty for Long Proximal Ureteral Stricture: 6 Years of Experience with 41 Cases. Eur Urol 2022;82:193-200. [Crossref] [PubMed]
13. Chai S, Zhou Y, Dong M, et al. Robotic ureteroplasty with lingual mucosa graft: a multi-institutional experience. Minerva Urol Nephrol 2025;77:500-7. [Crossref] [PubMed]
14. Zhou Y, Chai S, Xu K, et al. Effect of ureteral rest on surgical outcomes in adults with ureteral stricture undergoing reconstruction: a propensity score matching study. World J Urol 2025;43:186. [Crossref] [PubMed]
15. Autorino R, Eden C, El-Ghoneimi A, et al. Robot-assisted and laparoscopic repair of ureteropelvic junction obstruction: a systematic review and meta-analysis. Eur Urol 2014;65:430-52. [Crossref] [PubMed]
16. Vannahme M, Mathur S, Davenport K, et al. The management of secondary pelvi-ureteric junction obstruction - a comparison of pyeloplasty and endopyelotomy. BJU Int 2014;113:108-12. [Crossref] [PubMed]
17. Zhang P, Shi T, Fam X, et al. Robotic-assisted laparoscopic pyeloplasty as management for recurrent ureteropelvic junction obstruction: a comparison study with primary pyeloplasty. Transl Androl Urol 2020;9:1278-85. [Crossref] [PubMed]
18. So WZ, Tiong HY. Robotic-Assisted Laparoscopic Ureterocalicostomy for Persistent Uretero-Pelvic Junction (UPJ) Obstruction after Failed Renal Pyeloplasty. Eur Urol Open Sci 2022;37:1-2. [PubMed]
19. Kaouk JH, Kuang W, Gill IS. Laparoscopic dismembered tubularized flap pyeloplasty: a novel technique. J Urol 2002;167:229-31. [Crossref] [PubMed]
20. Lumen N, Vierstraete-Verlinde S, Oosterlinck W, et al. Buccal Versus Lingual Mucosa Graft in Anterior Urethroplasty: A Prospective Comparison of Surgical Outcome and Donor Site Morbidity. J Urol 2016;195:112-7. [Crossref] [PubMed]
21. Sinha RJ, Singh V, Sankhwar SN, et al. Donor site morbidity in oral mucosa graft urethroplasty: implications of tobacco consumption. BMC Urol 2009;9:15. [Crossref] [PubMed]
22. Joshi MS, Verma Y, Gautam AK, et al. Cytogenetic alterations in buccal mucosa cells of chewers of areca nut and tobacco. Arch Oral Biol 2011;56:63-7. [Crossref] [PubMed]
23. Xiong S, Wang J, Zhu W, et al. Onlay Repair Technique for the Management of Ureteral Strictures: A Comprehensive Review. Biomed Res Int 2020;2020:6178286. [Crossref] [PubMed]
24. Simonato A, Gregori A, Ambruosi C, et al. Lingual mucosal graft urethroplasty for anterior urethral reconstruction. Eur Urol 2008;54:79-85. [Crossref] [PubMed]
25. Scardino PL, Prince CL. Vertical flap ureteropelvioplasty. South Med J 1953;46:325-31. [Crossref] [PubMed]
26. Culp OS, Deweerd JH. A pelvic flap operation for certain types of ureteropelvic obstruction; observations after two years' experience. J Urol 1954;71:523-9. [Crossref] [PubMed]
27. Oesterwitz H, Bick C, Müller P, et al. Management of ureteropelvic junction obstruction using a microsurgical technique. Eur Urol 1987;13:412-4. [Crossref] [PubMed]
28. Basiri A, Behjati S, Zand S, et al. Laparoscopic pyeloplasty in secondary ureteropelvic junction obstruction after failed open surgery. J Endourol 2007;21:1045-51; discussion 1051. [Crossref] [PubMed]
29. Symons SJ, Bhirud PS, Jain V, et al. Laparoscopic pyeloplasty: our new gold standard. J Endourol 2009;23:463-7. [Crossref] [PubMed]
30. Li B, Xu Y, Hai B, et al. Laparoscopic onlay lingual mucosal graft ureteroplasty for proximal ureteral stricture: initial experience and 9-month follow-up. Int Urol Nephrol 2016;48:1275-9. [Crossref] [PubMed]
31. Fan S, Yin L, Yang K, et al. Posteriorly Augmented Anastomotic Ureteroplasty with Lingual Mucosal Onlay Grafts for Long Proximal Ureteral Strictures: 10 Cases of Experience. J Endourol 2021;35:192-9. [Crossref] [PubMed]
32. Yang K, Fan S, Wang J, et al. Robotic-assisted Lingual Mucosal Graft Ureteroplasty for the Repair of Complex Ureteral Strictures: Technique Description and the Medium-term Outcome. Eur Urol 2022;81:533-40. [Crossref] [PubMed]
33. Davis JE, Hagedoorn JP, Bergmann LL. Anatomy and ultrastructure of the ureter. In: Bergman H, editor. The Ureter. New York, NY: Springer New York; 1981. p. 55-70.
34. Nguyen AT, Buckley JC. A novel robotic ureteral reconstruction technique for complex proximal strictures renal pelvis flap augmentation and buccal mucosal graft. BMC Urol 2025;25:156. [Crossref] [PubMed]