Robot-Assisted Lingual Mucosa Graft Onlay Reconstruction for Ureteric Strictures Refractory to Endoscopic Treatment

Summary

Ureteric strictures often follow urological disease or therapy, with endoscopy as first-line treatment. For refractory cases, we report robot-assisted lingual mucosa graft onlay reconstruction, with detailed technique and initial outcomes. This approach aims to restore upper urinary tract patency and reduce surgical trauma and complexity.

Abstract

This study describes the detailed technique and initial experience with robot-assisted lingual mucosal graft onlay ureteric reconstruction (RLUR) in patients with ureteric strictures refractory to endoscopic treatment. Preoperative evaluation included contrast-enhanced CT with excretory phase, ureteroscopy, and ureterography. History taking, clinical examination, renal function measurement, and urinary tract echographic evaluation were used for postoperative follow-up. Recurrence of stricture was defined as the presence of ureteric narrowing, as proven by imaging with outflow obstruction above the site of reconstruction. Since 2017, fifteen patients underwent RLUR, with a median age of 53 years and a median stricture length of 3.0 cm. Strictures were located in the upper third (n = 7), mid third (n = 7), and lower third (n = 1) of the ureter, with a median of 3 prior interventions. Seven patients underwent graft-augmented anastomosis, while 8 received "classic" graft onlay. Median operative time was 215 min, with no intraoperative complications and 2 postoperative grade 3a complications (13%). At a median follow-up of 21 months, surgical success was achieved in 13 patients (87%), and the estimated two-year recurrence-free survival rate was 83%. These findings support RLUR as a safe and effective option for refractory ureteric strictures.

Introduction

Ureteric strictures are characterized by abnormal narrowing of a ureteric segment causing obstruction of the outflow of the upper urinary tract above this segment. The strictures may arise from diverse etiologies, including open or endoscopic surgical procedures, stones, trauma, radiotherapy, and so on¹. The clinical presentation and symptoms may vary, but left untreated, it may lead to progressive hydronephrosis and eventually functional loss of the ipsilateral kidney^2,3. The urinary outflow of the upper urinary tract can be temporarily restored by urinary drainage through a nephrostomy tube or JJ ureteric stent, but a definitive treatment of a ureteric stricture poses a specific challenge to the reconstructive urologist^4,5.

Endoscopic incision or dilation of a ureteric stricture is often attempted as first-line treatment, given the minimal invasiveness of this modality^6,7. Some patients will fail endoscopic treatment and will need further reconstruction⁸. Among different reconstructive options, robot-assisted graft onlay reconstruction with buccal mucosa graft was first reported by Zhao et al. in 2015 and has gained further dissemination since then^9,10,11. In urethral reconstruction, lingual mucosa has been proposed as an alternative to buccal mucosa, and both grafts are equally recommended as graft material¹². It is hypothesized that lingual mucosa could be used as a graft as well in ureteric reconstruction.

Within current treatment algorithms, RLUR may serve as a minimally invasive reconstructive option for patients with multiple failed endoscopic treatments who are unsuitable for ureteral reimplantation or reconstruction using other grafts (e.g., appendix)¹³. Its robotic approach could promote broader adoption of graft-based ureteric reconstruction in future urologic practice and provide evidence for a more standardized, protocol-driven selection of ureteric reconstructive techniques.

The aim of this study is to describe the surgical technique and initial experience of robot-assisted lingual mucosa graft onlay ureteric reconstruction (RLUR) for ureteric strictures that failed endoscopic treatment and whose stricture length (required graft length) is no more than 8 cm. It is hoped that this surgical procedure could reduce the trauma of patients during reconstructive surgery and provide more possible options for refractory ureteric strictures.

Protocol

Starting from 2017, this technique was decided to be offered to adult (≥18 years) patients with a ureteric stricture that failed at least one endoscopic treatment. Strictures in the lower third of the ureter amenable to psoas hitch repair (as determined by the surgeon) were excluded, as well as strictures longer than 8 cm, in which case unilateral lingual mucosa graft (LMG) harvest would not be possible. Patients with a condition in the oral cavity precluding the harvest of a healthy LMG and patients with an afunctional kidney at the affected side were also excluded. Patients provided written informed consent, and the study was approved by the ethics committee of Ghent University Hospital (UZG 2016/1364). The data cut-off was in March 2025. The reagents and the equipment used in this study are listed in the Table of Materials.

1. Preoperative management

NOTE: In cases of suspected ureteric stricture based on clinical history, such as prior endoscopic ureteral/renal surgery, history of nephrolithiasis, radiation therapy, or ureteral trauma, and symptoms including dull lumbar pain or urinary tract infections (UTI, e.g., pyelonephritis), follow this protocol:

1. Perform a renal ultrasound (US) to confirm the presence of hydronephrosis.
2. Confirm the diagnosis with a computed tomography urogram (uro-CT) to identify findings such as contrast extravasation, hydronephrosis, proximal ureteral dilation, or urinoma.
3. In equivocal cases, use urography and/or ureteroscopy as additional diagnostic tools.
4. If possible, remove a JJ-stent at least 6 weeks prior to surgery. In case of symptomatic obstruction, place a nephrostomy tube.
5. Conduct a preoperative urinalysis.
   1. For patients with a positive urine culture (≥10³ colony-forming unit/mL): (1) Initiate targeted antibiotic therapy 24 h before surgery based on antibiogram results; (2) Continue antibiotic therapy for at least 7 days postoperatively.
   2. For patients with a negative urinalysis, administer perioperative antibiotic prophylaxis, typically 2 g of the second-generation cephalosporin or 2.2 g of amoxicillin-clavulanic acid intravenously.
6. In cases of active UTI, perform surgery under antibiotic coverage.

2. Surgical procedure

1. Position of the patient
   1. Place the patient in a modified lateral decubitus position with the side of the affected ureter up. Administer general anesthesia (following institutionally approved protocols) and fix the endotracheal tube at the side of the mouth contralateral to the affected ureter. Slightly flex the table at the level of the patient's umbilicus to improve exposure.
   2. Pad and secure the upper arm at the patient's side, while extending the opposite arm perpendicular to the chest. Use an axillary roll to prevent brachial plexus injury.
   3. Support the shoulders and pelvis of the patient. Secure the patient using adhesive tape at the level of the pectoral area and the lower limbs. Flex the lower leg slightly, and keep the upper leg extended with a pillow in between to maintain alignment and prevent pressure injuries.
   4. Drape the genital region into the abdominal field to allow for concomitant ureteroscopy. Drape the oral cavity separately.
2. Sterile field preparation
   1. Perform aseptic preparation of the abdominal skin and include the genital area within the sterile field to facilitate intraoperative ureteroscopy.
   2. Also, prepare and drape the mouth separately from the rest of the surgical field and disinfect with chlorhexidine.
3. Trocar placement
   1. Achieve initial camera port (8 mm) placement 2 cm cephalad to the umbilicus, at the lateral border of the rectus abdominis muscle, using the open Hasson technique, and establish pneumoperitoneum.
   2. Insert the 30° camera and place the remaining 3 ports (8 mm) under direct vision: one at the costal margin (cranial to the camera trocar), another infraumbilically at the lateral border of the rectus (caudal to the camera trocar), and the third between the umbilicus and the anterior superior iliac spine (caudal to the camera trocar), ensuring adequate spacing between all ports, approximately 7-8 cm.
   3. Place the assistant trocar (12 mm) medial to the robotic ports, between the camera port and the inferior robotic port.
4. Robot placement
   1. Dock the robot at a right angle to the patient's back. Position the robot's screen cephalad to the robot, and place the cystoscope tower caudad to the robot, ensuring that both the bedside assistant and the surgeon performing the ureteroscopy have clear visibility of their respective screens.
   2. Connect the robotic arms with the trocars. Insert the robotic bipolar forceps with a curved tip in the left robot trocar, the scissors in the upper right trocar, and the needle driver in the lower right trocar to start the dissection (Figure 1).
5. Procedure
   1. Mobilize the descending colon (in patients with left-side ureteric stricture) along Toldt's line and define the plane between Gerota's fascia and the colon.
   2. Expose the psoas muscle and identify the overlying ureter at the crossing of the iliac vessels and in proximity to the gonadal vessels.
   3. Mobilize the ureter from caudal to cephalad. Respect the surrounding vessels while mobilizing the ureter as much as possible.
      NOTE: Fibrotic tissue is typically found around the ureteral stricture.
   4. Meanwhile, perform the ureteroscopy to identify the distal end of the stricture by another surgeon. If possible, pass a guidewire through the stricture (Figure 2). Switch off the light of the robot camera and use the light of the ureteroscope to identify the distal end of the ureteral stricture. Visually confirm that the ureteral lumen is patent distal to the stricture before proceeding.
   5. Incise the ureter just above the tip of the ureteroscope in a longitudinal fashion. Further, incise the ureteral stricture cephalad until healthy proximal ureteral mucosa is identified.
   6. Assess the length of the stricture and the degree of narrowing by direct evaluation and choose further techniques accordingly.
   7. In the presence of a short, nearly obliterative segment, resect the narrowed segment over a length of a maximum of 1 cm without transecting the underlying vessels. Suture the dorsal ends to each other with the 4-0 poliglecaprone suture and interrupted sutures to restore ureteral continuity but leave the spatulated ventral ends open (augmented end-toend technique).. Measure the length of the residual opened ventral segment.
   8. In the absence of a short, nearly obliterative segment, do not resect the ureteral segment. Measure the length of the opened ureteral stricture (Graft augmented technique).
   9. Proceed with the same further management for both techniques.
   10. Place the needle driver in the right upper trocar and the scissors in the right lower trocar.
   11. Place a 4-0 poliglecaprone suture at the proximal and distal ends of the opened ureter. Place the sutures outside-in and do not make a knot.
   12. Proceed with harvesting the LMG.
       1. Lingual mucosa graft harvest
          1. Use a dermatographic pencil to mark the dimensions of the graft on paper, ensuring a width of 15 mm and a length adjusted to the defect size.
          2. Place a traction 2-0 silk suture with a double pass (to avoid tearing injuries) on the lateral margin of the tongue. Suspend the suture using a mosquito clamp and have an assistant lift it to expose the harvest site.
          3. Position a mouth retractor to maintain exposure.
          4. Apply the pre-drawn template to the inferior lateral sublingual harvest site. Infiltrate the donor site with lidocaine hydrochloride 2% and epinephrine (1:200,000).
          5. Incise the graft borders using a cold scalpel blade 15 and raise it using Metzenbaum scissors, taking care to preserve the underlying tissues.
          6. Achieve hemostasis at the donor site using bipolar coagulation.
          7. Remove the mouth retractor.
          8. Spread the graft on the silicone plate using 25 G needles and defat the graft. Keep the graft moist throughout the process. Confirm uniform graft thickness, ensuring the mucosal side is clearly identifiable for later placement.
          9. Before the end of the procedure, evaluate the harvest site, perform minimal cautery for hemostasis if necessary, and confirm no bleeding.
   13. Introduce the graft into the abdomen through the assistant port, wrapped in gauze.
   14. Start the suturing of the graft using the already placed 4-0 poliglecaprone suture at the distal (caudal) end of the stricture. Verify the correct mucosal orientation before starting suturing (the mucosal side faces the ureteral lumen). Begin with the lateral side of the ureter.
       1. The needle is passed through the graft from the mucosal side to the submucosal side in order to place the mucosal side of the graft towards the ureteral lumen. Make a knot and further perform a running suture towards the proximal (cephalad) end of the stricture. Make a knot and cut the remaining suture.
   15. Suture the graft towards the medial side of the ureter using the above-mentioned running suture technique, but from proximal to distal.
   16. Assess the patency and water tightness of the reconstructed ureter by passing the ureteroscope through the segment. Confirm successful anastomosis by ensuring the ureteroscope passes smoothly and no leakage is observed at the anastomosis after normal saline injection. Also, confirm no bleeding around the anastomosis sites before concluding the procedure.
   17. Suture the graft to the perirenal fat to promote graft integration using interrupted 4-0 poliglecaprone sutures.
   18. Insert a JJ ureteral stent in the retrograde manner using the previously placed guidewire.
   19. Insert a urinary catheter and a closed suction drain adjacent to the reconstructed ureteral segment.
   20. Remove the instruments and trocars and close the port sites with staplers.

3. Postoperative management

1. Hospital stays and initial care
   1. Keep the patient admitted postoperatively with a Foley catheter, surgical drain, and JJ stent in place.
   2. Monitor the drainage output and its characteristics in the early postoperative period to detect any signs of urinary leakage. Remove the drain on the first postoperative day if the patient is in good general condition, shows no clinical signs of infection or active bleeding, and laboratory tests indicate no evidence of bleeding or leakage. Discharge the patient with the Foley catheter and JJ stent in place.
2. Cystographic evaluation
   1. Perform an outpatient retrograde cystography on postoperative days 7 to 10. Slowly infuse an iodinated contrast medium into the bladder through the Foley catheter until ureteral reflux occurs, typically after more than 250 mL.
   2. Assess the presence or absence of contrast extravasation at the anastomotic site. If no extravasation is observed, remove the Foley catheter.
3. Stent removal
   1. Remove the JJ stent 6 weeks postoperatively during an outpatient flexible cystoscopy procedure. Extend retention time in the presence of para-ureteric collection.
4. Follow-up protocol
   1. Schedule follow-up evaluations at 3 months, 6 months, 12 months, and 24 months postoperatively, with additional visits as needed. Assess clinical success based on the absence of symptoms related to ureteral obstruction.
   2. Monitor renal function through serum creatinine levels. Evaluate the presence or absence of hydronephrosis using US. Perform a CT scan with urographic phases at the physician's discretion for further assessment.
   3. Define recurrence as the presence of ureteric narrowing proven by imaging with outflow obstruction above the site of reconstruction. Report postoperative complications within 90 days according to the Clavien-Dindo classification¹⁴.
5. Postoperative oral care following lingual mucosal graft harvest
   1. Oral hygiene: Start patients on a cold liquid diet on the first postoperative day, and advance to a normal diet on the following day. Administer a 10 mL sachet of sodium alginate and potassium bicarbonate suspension three times daily before meals.
      1. After each meal, instruct the patient to thoroughly rinse the oral cavity with a 0.12% chlorhexidine mouthwash. Maintain this regimen until the donor site has completely healed.
   2. Dietary recommendations: Advise the patient to avoid milk and dairy products during the healing period, as these may promote bacterial proliferation in the oral cavity and increase the risk of infection.

4. Statistics

1. Perform descriptive statistics to evaluate the study population. Continuous data were reported as median with interquartile range (IQR), and categorical data were reported as numbers with proportion (%).
   NOTE: The 2-year recurrence-free survival rate was calculated using the Kaplan-Meier method (Figure 3).

Results

From 2017 to 2025, 15 patients were included (Table 1). Median age was 53 (IQR 39-62) years. The location was at the upper, mid, and lower third of the ureter in resp. 7 (47%), 7 (47%), and 1 (7%) patients. The median stricture length was 3 (IQR 2-3.2) cm, and the maximum length was 8 cm. Urolithiasis treated by ureteroscopy was the main etiology, affecting 10 (67%) patients.Other etiologies encompassed failed pyeloplasty, tuberculosis, and idiopathic in resp. 3 (20%), 1 ...

Discussion

For proximal and mid ureteric strictures, common reconstruction procedures include ureteroureterostomy, ileal ureteric replacement, appendiceal flap ureteroplasty, etc. Despite the variety of options available, these techniques present their own unavoidable shortcomings^1,15. Ureteroureterostomy is indicated for short-segment strictures with limited applicability (max 4cm). It requires adequate mobilization of the ureter to achieve a tension-free anastomosis, ofte...

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Doyen Tongue Spatula	Tontarra Extranet	114-463-16	tongue retractor
AirSeal iFS Insufflator trocar	ConMed	iAS8-120LP	insufflation management system
Denhard mouth gag	Integra	3734151	mouth retractor
Dentio 0.12%	I. D. Phar	2416352	0.12% chlorhexidine mouthwash
Gaviscon Advance Mint 10 mL	Reckitt Benckiser	PL 00063/0748	sodium alginate and potassium bicarbonate
Monocryl	Ethicon	Y496G	poliglecaprone suture (absorbable, synthetic, monofilament)
Silkam	B. Braun	L153	silk suture (non-absorbable, natural, braided)
Vicryl	Ethicon	VCP250H	polyglactin suture (absorbable, synthetic, braided)
Vicryl rapide	Ethicon	V2930G	polyglactin suture (absorbable, synthetic, braided)
Xylocaine	Aspen Pharmacare	284106	xylocaine 2% and epinephrine 1:200000