Subtrigonal Inlay and Related BMG Approaches for Posterior Stenosis
Subtrigonal inlay refers here to the specific robotic transvesical buccal graft operation described by Avallone, Flynn and colleagues. Perineal dorsal onlay and transurethral grafting are related tissue-augmentation approaches, but are not all the same named technique. Their anatomy, selection and evidence must remain separate.[1]
Robotic subtrigonal inlay
The original report involved one 70-year-old man with refractory bladder-neck contracture after photovaporization of the prostate. Multiple endoscopic interventions had failed.[1]
The robotic transvesical approach provides intravesical exposure, opens the stenosis and inlays buccal mucosa at the subtrigonal/posterior bladder-neck defect. Preserve viable tissue, protect the ureteral orifices, secure graft contact with its recipient bed and close the cystotomy. The original video supplies the technique-specific incision and graft orientation; this should not be replaced with the pubic-periosteal quilting steps of a perineal operation.
| Index-case finding | Result |
|---|---|
| Graft dimensions as reported | 5 × 5 × 4 cm |
| Hospital discharge | Postoperative day 2 |
| Catheters | Urethral catheter 2 weeks; suprapubic catheter 4 weeks |
| Healing assessment | VCUG at 4 weeks without obstruction or extravasation |
| Flow and residual | Qmax 2 to 27 mL/s; PVR 200 to 3 mL |
| Recurrence | None at reported last follow-up; the abstract does not provide a durable comparative endpoint |
This is technical feasibility evidence, not a 100% expected success rate. Its catheter schedule is a case-specific protocol, not a universal rule.[1]
Related approaches
| Approach | Anatomical distinction | Evidence scope |
|---|---|---|
| Perineal dorsal BMG | Dorsal urethral opening reached from below; graft bed depends on technique | Observational cohorts with different stenosis sites and radiation exposure |
| Endoscopic BMG | Transurethral recipient-bed preparation and graft delivery | Small cohorts and technical cases; no proven superiority |
| Single-port robotic BMG | Robotic graft placement, sometimes with additional flap or perineal work | Liu's nine-patient series had mean defect length 3.9 cm; 5 required ancillary tissue transfer, median operative time 377 minutes and follow-up 11.7 months; complications included SBO requiring surgery. It had no open comparator.[2] |
| Y-V plasty | Native bladder-flap advancement into an opened stenosis | It is not synonymous with circumferential excision and primary reanastomosis |
Interpreting posterior BMG evidence
Angulo's 107-patient study involved membranous/bulbomembranous stenoses after benign prostate surgery and excluded BNC. It reported 10 recurrences at mean 59.3 months and one new SUI event among 87 patients known continent before surgery. It cannot establish subtrigonal inlay or dorsal BMG as the best treatment for post-TURP BNC.[3]
Sterling's 45-patient post-prostatectomy/post-radiation cohort included 21 anastomotic and 24 bulbomembranous stenoses, with seven recurrences. No new SUI was reported, but the publication's continence counts are internally inconsistent; do not portray this as 0/45 initially continent patients. Policastro's 79-patient post-radiation series reported 14 recurrences and 3/37 new SUI cases among initially continent patients, at median 21 months.[4][5]
The five new SUI events among six VUAS patients in Viegas's Y-V series cannot be compared directly with those different BMG cohorts to establish a dramatic treatment advantage. Differences in anatomy, baseline function and selection are substantial. Radiation remains clinically relevant, but these studies do not prove that BMG always tolerates it better than excisional repair.[6][4][5]
Clinical role
Use a viable graft bed, secure fixation and drainage, and discuss oral donor-site morbidity and the possibility of recurrence or incontinence. BMG augmentation can preserve continuity in appropriate anatomy; it does not guarantee preservation of the external sphincter.
Choose reconstruction according to stenosis site, length, residual lumen, radiation/tissue damage, bladder function, continence and the patient's goals. No guideline establishes subtrigonal inlay or dorsal BMG as the universal preferred treatment for radiated or nonradiated VUAS. Complete posterior obliteration should not undergo endoluminal treatment. Subsequent AUS surgery requires stable patency and individualized risk assessment.[7]
Anterior/bulbar dorsal-versus-ventral graft meta-analyses and surgeon-preference surveys cannot answer which posterior operation is best. Broader graft biology is covered in the foundations articles; procedure selection here rests on the posterior anatomy and available clinical evidence.
Videos
References
1. Avallone MA, Quach A, Warncke J, Nikolavsky D, Flynn BJ. "Robotic-Assisted Laparoscopic Subtrigonal Inlay of Buccal Mucosal Graft for Treatment of Refractory Bladder Neck Contracture." Urology. 2019;130:209. doi:10.1016/j.urology.2019.02.048
2. Liu W, Shakir N, Zhao LC. "Single-Port Robotic Posterior Urethroplasty Using Buccal Mucosa Grafts: Technique and Outcomes." Urology. 2022;159:214-221. doi:10.1016/j.urology.2021.07.049
3. Angulo JC, Dorado JF, Policastro CG, et al. "Multi-Institutional Study of Dorsal Onlay Urethroplasty of the Membranous Urethra After Endoscopic Prostate Procedures: Operative Results, Continence, Erectile Function and Patient Reported Outcomes." Journal of Clinical Medicine. 2021;10(17):3969. doi:10.3390/jcm10173969
4. Sterling J, Simhan J, Flynn BJ, et al. "Multi-Institutional Outcomes of Dorsal Onlay Buccal Mucosal Graft Urethroplasty in Patients With Postprostatectomy, Postradiation Anastomotic Stenosis." The Journal of Urology. 2024;211(4):596-604. doi:10.1097/JU.0000000000003848
5. Policastro CG, Simhan J, Martins FE, et al. "A Multi-Institutional Critical Assessment of Dorsal Onlay Urethroplasty for Post-Radiation Urethral Stenosis." World Journal of Urology. 2021;39(7):2669-2675. doi:10.1007/s00345-020-03446-y
6. Viegas V, Freton L, Richard C, et al. "Robotic YV Plasty Outcomes for Bladder Neck Contracture vs. Vesico-Urethral Anastomotic Stricture." World Journal of Urology. 2024;42(1):172. doi:10.1007/s00345-024-04814-8
7. European Association of Urology. EAU Guidelines on Urethral Strictures. 2026. Disease management in males, sections 6.3.5–6.3.6. Guideline.