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BMG Endourethroplasty

BMG endourethroplasty is the family of fully endoscopic / transurethral techniques that place a buccal mucosal graft (BMG) — or related tissue graft — into a urethral stricture or stenosis without any external incision. The concept spans from early preputial-skin graft techniques described in 1988 to modern BMG-based onlay, inlay, tubular, and injectable-micrograft approaches.

Non-graft endoscopic mucosal-rearrangement techniques such as transurethral incision with transverse mucosal realignment (TUITMR) sit in a parallel category — same minimally invasive philosophy, but no graft — and are covered on their own page.

Historical Origins​

The term "endourethroplasty" was first used by Chiou (1988), who described a 2-step endoscopic procedure for complicated posterior urethral strictures:[1]

  1. Transurethral resection of scar tissue to create a smooth grafting bed.
  2. Full-thickness preputial graft placed at the stricture site, held in place by an intraluminal balloon catheter.

Outcomes: 2 of 3 patients remained stricture-free for >22 months and 1 for >12 months. Proof of concept that endoscopic graft placement was feasible, though not widely adopted due to technical limitations of the era.[1]

1. Doležel Endourethroplasty (EUP) — BMG via Endourological Approach​

The technique most specifically referred to as "endourethroplasty" in the contemporary literature. Doležel et al. reported a 23-year single-center experience (1999–2022) with 38 patients, of whom 11 (29%) underwent EUP.[2]

Technique​

  • The stricture (VUAS or membranous urethral stenosis) is dilated and/or incised endoscopically.
  • A buccal mucosal graft is configured as either an onlay (for partial stenosis with residual urethral plate) or a tubular graft (for complete obliteration).
  • The BMG is delivered endoscopically into the stricture site and secured in position.
  • A catheter stents the graft during healing.
  • If a short recurrence occurs within 12 months, a cold-knife "auxiliary" DVIU is permitted — considered part of the treatment protocol, not a failure.

Outcomes (n=11)[2]​

  • 3-year stricture recurrence-free survival: 73% — numerically superior to the perineal approach (63%) in the same cohort.
  • With permitted auxiliary DVIU, 3-year SRFS for the entire cohort improved to 81%.
  • De novo incontinence: 2 of 18 preoperatively continent patients (11%) across both approaches.
  • The authors concluded EUP is a "promising minimally invasive alternative to the perineal approach."

Advantages over the perineal approach​

  • No perineal incision → reduced morbidity, faster recovery.
  • Avoids urethral mobilization → preserves periurethral vasculature.
  • Comparable or numerically superior patency at 3 years.

Limitations​

  • Small sample size (n=11).
  • Heterogeneous cohort (mixed VUAS and PUS etiologies).
  • Single-center, retrospective.
  • Technical details of graft fixation are less well described than other techniques.

2. Ungerer / Warner Endoscopic Urethroplasty — BMG via RD180 Suturing Device​

Ungerer et al. (2023) described a novel fully endoscopic technique using the RD180 endoscopic suturing device (the same device used for endoscopic bariatric procedures), developed at the Warner group.[3]

Technique​

  1. Patient: Post-radiation prostate cancer patient with 8 mm flow-limiting membranous urethral stricture.
  2. Stricture dilation: The stricture is dilated to allow passage of instruments.
  3. Mucosal-bed creation: Using a resectoscope, a 1 cm wide strip of superficial mucosa is resected from the bladder neck past the area of stricture — creating a raw, vascularized bed for graft take (analogous to the periosteal bed in open dorsal onlay).
  4. BMG harvest: Standard buccal mucosal graft harvest from the inner cheek.
  5. Graft delivery via pulley technique:
    • The BMG is positioned outside the urethra.
    • The RD180 is passed transurethrally.
    • A suture is placed through the proximal end of the graft, then through the bladder neck, and back through the graft.
    • As the suture is pulled, the "pulley phenomenon" advances the graft into position on the bladder neck — the key technical innovation.
  6. Graft fixation: Anchored to the posterior urethra with secure straps; sutures secured with the Ti-Knot fastener.
  7. Catheter management: Catheter holds the graft flat during healing; removed at 4 weeks.

Outcomes (n=1, proof of concept)[3]​

  • Operative time: 2.5 hours; EBL: 50 mL; same-day discharge.
  • Cystoscopy at 10 weeks: good graft viability.
  • Qmax improved from 4 → 20 mL/s.
  • No recurrence at 6 months.

The most detailed step-by-step description of fully endoscopic BMG placement for posterior urethral pathology to date. Single case report — requires significant validation.

3. Transurethral Inlay BMG Urethroplasty (TBMGI) — Sterling / Nikolavsky / Vanni​

Originally described for distal / fossa navicularis strictures rather than posterior strictures, but the most mature endourethroplasty technique with the largest evidence base.[6][7][8]

Technique (ventral inlay)​

  1. Cicatrice excised via transurethral ventral urethrotomy until lumen ≥ 24 Fr.
  2. Double-arm 6-0 PDS suture delivers a triangular BMG to the proximal extent of the urethrotomy, secured externally.
  3. Graft secured to meatus with 5-0 polyglactin sutures; additional 6-0 PDS quilting sutures for spread fixation.
  4. 16 Fr silicone catheter placed; void trial at 1 week.

Outcomes​

SeriesnStricture locationSuccessFollow-up
Sterling 2023 (single institution)[6]44Fossa navicularis / distal95%36 mo (mean)
Daneshvar 2020 (12 institutions)[7]68Fossa navicularis / distal95%17 mo (median)
Farrell 2022 (dorsal inlay variant)[8]16Fossa navicularis93.8% anatomic / 100% functional28.8 mo (median)

Dorsal inlay variant (Farrell / Vanni): Places the BMG dorsally rather than ventrally through a transurethral approach — glans-sparing, avoids splitting the glans, excellent cosmesis (83.3% very satisfied).[8]

4. Liquid Buccal Mucosal Graft (LBMG) Endourethroplasty — Nikolavsky​

The most experimental endourethroplasty concept — injectable BMG micrografts suspended in fibrin glue, delivered endoscopically after DVIU.[9][10]

Concept​

Rather than placing a solid sheet of BMG, buccal mucosa is mechanically minced into micrografts suspended in fibrin glue. This liquid mixture is injected into the urethrotomy site after DVIU, where the micrografts engraft and re-epithelialize the incised stricture with buccal mucosa rather than allowing fibrotic scar reformation.

Animal data​

  • Phase 1 (Nikolavsky 2016): 3 rabbits — 2/3 demonstrated buccal mucosa engraftment after LBMG injection. Phase 2: 6 treated rabbits all showed engraftment with stricture resolution/improvement on RUG and urethroscopy at 8–24 weeks. Controls (fibrin glue only) showed fibrosis and chronic inflammation with no engraftment.[9]
  • Validation study (Scott 2020): 26 rabbits randomized to DVIU + LBMG vs DVIU + fibrin glue only. 67% (8/12) of LBMG-treated animals demonstrated engraftment vs 0% in controls (p=0.0005). Radiographic improvement 58% vs 38% (p=0.145, ns); median percent change in urethral diameter 59% vs 41.6% (p=0.29).[10]

Currently in preclinical / proof-of-concept phase; no human data published. Attractive because it would eliminate the need for endoscopic suturing devices and complex graft delivery — LBMG could theoretically be injected through a simple needle after any DVIU.

Comparative Overview — All Endourethroplasty Techniques​

TechniqueDeveloper(s)Location treatednSuccessDe Novo SUIMaturity
EUP (BMG onlay/tubular)[2]DoleželVUAS / membranous1173% 3-yr SRFS11% (combined)Moderate (23-yr experience)
Endoscopic BMG (RD180)[3]Ungerer / WarnerMembranous1100% (6 mo)0%Proof of concept
TBMGI — ventral inlay[6][7]Sterling / NikolavskyFossa navicularis / distal112 (combined)95%0%Mature (multi-institutional)
TBMGI — dorsal inlay[8]Farrell / VanniFossa navicularis1693.8%0%Early (single-center)
Liquid BMG (LBMG)[9][10]NikolavskyBulbar (animal model)26 rabbits67% engraftmentN/APreclinical only
2-step preputial graft[1]Chiou (1988)Posterior3100% (12–22 mo)N/AHistorical

Endourethroplasty in the Treatment Algorithm​

A 2025 review by Hudson et al. synthesized the evolving landscape of minimally invasive treatments for posterior urethral stenosis:[5]

  • Traditional endoscopic treatments (DVIU, dilation ± injectables) have success rates of 40–72%, with 90% of patients requiring repeat intervention within 2 years.
  • Novel endoscopic techniques (drug-coated balloon dilation, TUITMR, endourethroplasty) demonstrate short-term success rates approaching 85–90% — a significant improvement.
  • These techniques are particularly valuable because definitive open/robotic reconstruction requires joint abdominoperineal approaches and is less utilized outside academic centers with reconstructive urologists.
  • The AUA 2023 guideline endorses robotic or open reconstruction for recalcitrant VUAS/BNC (Conditional Recommendation, Grade C) but does not yet specifically address endourethroplasty techniques, which postdate the guideline evidence review.[18]

Key Principles Across All Endourethroplasty Techniques​

  1. Graft-bed vascularity is critical — whether using a resected mucosal bed (Ungerer), periosteum (open dorsal onlay), or native bladder mucosa (mucosal realignment), the graft must contact a vascularized surface for imbibition and neovascularization.
  2. Sphincter preservation — all endourethroplasty techniques avoid urethral transection, resulting in near-zero de novo incontinence rates across all series.
  3. Catheter stenting duration varies — from 1 week (TBMGI for distal strictures) to 4 weeks (Ungerer technique) to 3 weeks (Doležel EUP), reflecting differences in graft healing biology at different urethral locations.
  4. "Auxiliary" DVIU concept — Doležel's protocol permits a single cold-knife incision for short recurrences within 12 months, viewing this as part of the treatment rather than failure. Improved 3-year SRFS from 65% to 81%.[2]
  5. Patient selection — endourethroplasty is best suited for short stenoses without long-segment obliteration; longer or densely fibrotic defects are better managed by open or robotic reconstruction.[2][5]

Future Directions​

The field is moving toward increasingly minimally invasive approaches. The liquid BMG concept (injectable micrografts) could theoretically make endourethroplasty as simple as a DVIU with injection — no suturing device needed.[9][10] Drug-coated balloons are gaining traction as a non-graft alternative with growing evidence.[11][14] The convergence of these technologies — potentially combining DCB dilation with LBMG injection — represents a frontier that could fundamentally change how posterior urethral stenosis is managed, though all of these approaches require substantially more validation before displacing established open and robotic techniques.[5]

References​

1. Chiou RK. "Endourethroplasty in the Management of Complicated Posterior Urethral Strictures." The Journal of Urology. 1988;140(3):607-10. doi:10.1016/s0022-5347(17)41735-6

2. Doležel J, Hrabec R, Uher M, et al. "Substitution Urethroplasty With Buccal Mucosal Graft in the Management of Stricture of Vesicourethral Anastomosis or Membranous Urethra: Single-Institution Long-Term Experience With Perineal Approach and Endourethroplasty." Urology. 2024;192:126-132. doi:10.1016/j.urology.2024.05.034

3. Ungerer G, Kemble J, Sischka M, Balzano FL, Warner JN. "Endoscopic Urethroplasty Using Buccal Graft for Male Membranous Urethral Stricture." Urology. 2023;181:e200-e203. doi:10.1016/j.urology.2023.05.059

5. Hudson CN, Damm T, Monn MF. "Minimally Invasive Treatments for Posterior Urethral Stenosis." Journal of Endourology. 2025. doi:10.1177/08927790251371037

6. Sterling J, Daneshvar M, Nikolavsky D. "Transurethral Ventral Inlay Buccal Mucosa Graft Urethroplasty: Technique and Intermediate Outcomes." BJU International. 2023;132(1):109-111. doi:10.1111/bju.16007

7. Daneshvar M, Simhan J, Blakely S, et al. "Transurethral Ventral Buccal Mucosa Graft Inlay for Treatment of Distal Urethral Strictures: International Multi-Institutional Experience." World Journal of Urology. 2020;38(10):2601-2607. doi:10.1007/s00345-019-03061-6

8. Farrell MR, Campbell JG, Zhang L, Nowicki S, Vanni AJ. "Transurethral Reconstruction of Fossa Navicularis Strictures With Dorsal Inlay Buccal Mucosa Graft Urethroplasty." World Journal of Urology. 2022;40(6):1523-1528. doi:10.1007/s00345-022-03994-5

9. Nikolavsky D, Manwaring J, Bratslavsky G, et al. "Novel Concept and Method of Endoscopic Urethral Stricture Treatment Using Liquid Buccal Mucosal Graft." The Journal of Urology. 2016;196(6):1788-1795. doi:10.1016/j.juro.2016.05.028

10. Scott KA, Li G, Manwaring J, et al. "Liquid Buccal Mucosa Graft Endoscopic Urethroplasty: A Validation Animal Study." World Journal of Urology. 2020;38(9):2139-2145. doi:10.1007/s00345-019-02840-5

11. Berg EK, Mehmedovic S, Askari D, et al. "Efficacy of Drug-Coated Balloon Dilation vs. Endoscopic Standard Treatment in Posterior Urethral Stenosis: A Real-World Comparative Study." Urology. 2025. doi:10.1016/j.urology.2025.07.034

14. DeLong J, Virasoro R, Pichardo M, et al. "Long-Term Outcomes of Recurrent Bulbar Urethral Stricture Treatment With the Optilume Drug-Coated Balloon: Five-Year Results From the ROBUST I Study." The Journal of Urology. 2025;213(1):90-98. doi:10.1097/JU.0000000000004229

18. Wessells H, Morey A, Souter L, Rahimi L, Vanni A. "Urethral Stricture Disease Guideline Amendment (2023)." The Journal of Urology. 2023;210(1):64-71. doi:10.1097/JU.0000000000003482