Organ-Sparing USF Repair with Interposition Flap
The organ-sparing bladder-sparing USF repair with interposition flap — described primarily by Kaufman, Zinman, and Vanni (Lahey) — is the most conservative definitive surgical option for urosymphyseal fistula (USF). It avoids both prostatectomy and urinary diversion, achieving fistula closure through pubic-symphysis debridement, primary fistula-tract closure, and interposition of a well-vascularized flap between the urinary-tract repair and the debrided bone.[1][2]
For the broader bladder-sparing decision framework see USF / PPF Bladder-Sparing Approaches; for the more extensive bladder-sparing alternative see Salvage Prostatectomy for USF; for cystectomy / ileal conduit see the male fistula treatment atlas.
Rationale
In appropriately selected patients, the fistula is a localized anterior communication between the prostatic urethra / bladder neck and the pubic symphysis that can be addressed by:
- Removing the infected bone — the "sink" for chronic infection
- Closing the urinary-tract defect — the "source" of the leak
- Interposing healthy, non-irradiated, well-vascularized tissue to separate the two and promote healing in a radiation-compromised field[1][2]
Philosophically aligned with the principle that tissue interposition is mandatory in irradiated fistula repair — primary closure alone has unacceptably high failure rates.[3][4]
Patient Selection
The most critical aspect — appropriate for a narrow subset of USF patients.
Favorable characteristics
- Localized, well-defined anterior fistula tract — discrete communication, no extensive cavitation or multiple tracts[1][2]
- Adequate bladder function — no severe radiation cystitis, adequate capacity, no intractable hematuria[1][5]
- Viable sphincter mechanism — must be functional enough to maintain continence after repair[5]
- No distal urethral obstruction — patients with obstruction, radiation cystitis, or non-viable sphincter were triaged to anterior exenteration in Escandón 2026[5]
- Urinary-tract defect amenable to primary closure — small enough to close in multiple layers
Unfavorable characteristics (favor cystectomy or salvage RP + augmentation)
- End-stage irradiated bladder
- Extensive cavitation or necrosis surrounding the prostate
- Destroyed sphincter mechanism
- Multiple fistula tracts
- Prior multiple failed repairs
- Sequential multiple energy sources (EBRT + brachy + cryo / HIFU)[3]
Kaufman / Vanni Index Series (Lahey, 2006–2015)
- 4 patients over a consecutive 10-year period — underscores the rarity of ideal candidates at a high-volume reconstructive center
- All had prior pelvic radiation for prostate cancer
- All presented with pubic osteomyelitis
- All underwent pubic-symphysis debridement + fistula closure + rectus abdominis muscle flap interposition
- 100% (4/4) successful closure with a single procedure at median 27 mo — no prostatectomy or urinary diversion required[1]
Surgical Technique
Step 1 — Positioning and incision
- Supine with frog-leg or lithotomy lower extremities (for perineal access if needed)
- Midline lower abdominal incision from below the umbilicus to the pubic symphysis
- Incise the anterior rectus sheath; separate the rectus muscles in the midline to access the retropubic space[1][2]
Step 2 — Retropubic dissection and fistula identification
- Enter the retropubic space — typically obliterated by fibrosis, chronic inflammation, often urinoma
- Identify the fistula tract from the anterior prostatic urethra / bladder neck to the symphysis
- Delineate tract, symphyseal involvement, and relationship to bladder and prostate[1][2]
Step 3 — Pubic-symphysis debridement
- Resect all infected and necrotic bone using rongeurs, curettes, and / or osteotomes until healthy bleeding bone margins are encountered
- Bone cultures — essential, given the 95.5% discordance between preoperative urine and intraoperative bone cultures[6]
- Send specimens for pathology to rule out malignancy
- Extent varies from partial symphysectomy to near-complete pubectomy depending on osteomyelitis[1][6]
Step 4 — Fistula excision and urinary-tract closure
- Completely excise the tract back to healthy tissue
- Close the urinary-tract defect (prostatic urethra or bladder neck) primarily in multiple layers with absorbable suture
- Confirm watertight closure
- Leave an 18–20 Fr urethral catheter for postoperative drainage[1][2]
Step 5 — Interposition flap
The defining step. Multiple flap options exist — the rectus abdominis muscle flap is the Kaufman / Vanni default because of its immediate adjacency, but the choice should be individualized to anatomy, prior surgery, and surgeon experience.
Primary option — Rectus abdominis muscle flap
- Select one of the rectus abdominis muscles (typically ipsilateral to the fistula)
- Mobilize from posterior sheath while preserving the inferior epigastric artery pedicle (dominant blood supply) — meticulous preservation is essential[7]
- Divide superiorly (above the level needed for adequate length); detach superior insertions
- Rotate inferiorly on the inferior epigastric pedicle and transpose into the retropubic space
- Position to completely interpose between the urinary-tract closure and the debrided symphyseal bone bed
- Secure with absorbable suture; ensure dead-space obliteration and a barrier of well-vascularized, non-irradiated tissue[1][2][7]
Why the rectus muscle flap?
- Immediately adjacent — no additional incision or repositioning
- Large volume of well-vascularized muscle on a reliable pedicle (inferior epigastric artery)
- Can be harvested as a muscle-only flap (no skin paddle) — minimizes donor-site morbidity (vs full VRAM which adds a skin island and creates a larger abdominal-wall defect with a 16.7% donor-site hernia rate)[9]
- Effectively obliterates retropubic dead space
- Robertson 1986 — originally described as an alternative to omentum when prior abdominal surgery precludes omental mobilization; no adverse functional or cosmetic abdominal-wall result[7]
Alternative flaps (when rectus is unavailable or anatomy disfavors it)
| Flap | When to choose | Outcomes |
|---|---|---|
| Omental flap | Best safety profile in comparative analysis; mobilize on right gastroepiploic pedicle | Escandón 2026 (n = 34): 90-d sepsis 3%, lowest fistula recurrence; OR 0.012 for recurrence vs primary repair (P = 0.011)[5] |
| Gracilis muscle flap | Better for perineal / posterior approaches | Paprottka — shorter OR (3:11 vs 5:31 h vs VRAM) and better continence restoration in complex urogenital fistula[10] |
| Perivesical fat rotational flap | Prior abdominal surgery / no omentum / no rectus available | Hwang 2023 — wide-based pedicle of perivesical fat over the bladder dome rotated to interpose; successful in 3 cases at 1 mo – 3 yr[12] |
Step 6 — Drain placement and closure
- Closed-suction drains in the retropubic space adjacent to the flap
- Close the anterior rectus sheath (contralateral rectus intact — preserves abdominal-wall integrity)
- Layered wound closure
Postoperative Management
- Urethral catheter 2–4 weeks
- Cystogram before catheter removal to confirm no leak
- Culture-directed antibiotics for osteomyelitis — typically 6–8 wk based on intraoperative bone cultures[6]
- Drain removal when output minimal (5–7 d)
- Activity restriction — limited weight-bearing and no heavy lifting for 6–8 wk to protect the abdominal wall and allow flap incorporation
Outcomes
| Outcome | Kaufman / Vanni 2016 (n = 4) | TURNS Multicenter 2017 — bladder-sparing arm (n = 12) |
|---|---|---|
| Fistula closure | 100% (4/4) | 92% (11/12; 1 recurrence → cystectomy) |
| Procedures to close | 1 (all patients) | 1 (11/12) |
| Median follow-up | 27 mo | 6 mo |
| Pain resolution | NS | 84% (overall cohort)[8] |
| Major complications (≥ Grade III) | NR | 4 (30-d) / 2 (90-d) across entire cohort[8] |
| Need for prostatectomy | 0% | NS |
| Need for urinary diversion | 0% | 1/12 (8.3%) — for recurrence |
Flap-Selection Comparative Data
Escandón 2026 (n = 56) comparing primary repair vs omental vs VRAM:[5]
| Parameter | Primary repair (n = 11) | Omental flap (n = 34) | VRAM flap (n = 11) | P |
|---|---|---|---|---|
| 90-day sepsis | 18% | 3% | 27% | 0.041 |
| Fistula recurrence | 30% | Lowest | 27.3% | 0.04 |
| OR for recurrence (MVA) vs primary | Reference | 0.012 | NS | 0.011 |
The omentum had the best safety profile (significantly lower 90-d sepsis and fistula recurrence vs primary repair). Omentum was not statistically superior to VRAM for late recurrence. The muscle-only rectus (Kaufman / Vanni technique) was not separately analyzed but shares anatomy / pedicle with VRAM — the Kaufman / Vanni variant is a muscle-only flap (no skin paddle), avoiding the donor-site hernia burden of full VRAM.[9]
Advantages
- Preserves bladder — no urinary diversion or external appliance
- Preserves prostate — avoids salvage-RP morbidity in an irradiated field (rectal injury, blood loss, prolonged OR)
- Preserves native voiding — no CIC required
- Shorter, less complex operation than salvage RP + augmentation + stoma
- No bowel surgery — avoids metabolic complications of intestinal augmentation and stomal stenosis (27–33%)
- 100% single-procedure closure rate in the index series[1]
Limitations and Caveats
- Very small experience — only 4 patients in the index series over 10 years, reflecting narrow selection[1]
- No long-term data beyond 27 mo median follow-up
- Does not address the underlying radiation-damaged prostatic urethra — patients remain at risk for recurrent BNC or posterior urethral stenosis (the precipitating event for most fistulas)
- Risk of persistent bladder-outlet dysfunction — Raup 2016: 90% of irradiated patients developed subsequent BNC or SUI vs 14% of non-irradiated (P = 0.0006) even after successful fistula closure. Many patients may ultimately require urinary diversion despite initially successful bladder-sparing repair.[11]
- Radiation-associated repair failure — Eswara 2015: pelvic radiation significantly associated with fistula repair failure (P = 0.0002) and permanent urinary diversion (72% irradiated vs 7% non-irradiated at final follow-up)[4]
- Abdominal-wall morbidity — harvesting the rectus muscle creates a unilateral wall deficiency (Robertson 1986 reported no adverse functional / cosmetic result)[7]
Where This Approach Fits in the USF Algorithm
The organ-sparing interposition-flap repair is the least morbid definitive surgical option for USF but applies to the fewest patients:
- Conservative management (catheter, antibiotics) — fails in 96% of irradiated patients[8]
- Organ-sparing fistula repair with interposition flap → patients with localized fistula, adequate bladder, viable sphincter, amenable urinary defect (~14% of irradiated patients)[1][8]
- Salvage prostatectomy + augmentation + continent stoma → prostate in situ, adequate bladder, but non-viable sphincter or larger defect (~14% of irradiated patients)
- Cystectomy + ileal conduit → end-stage bladder, extensive tissue destruction, or failed prior repair (~86% of irradiated patients)[8]
Counsel patients about possible eventual urinary diversion given high rates of persistent bladder-outlet dysfunction in irradiated patients even after successful fistula closure.[4][11]
Key Takeaways
- Most conservative definitive USF operation — preserves bladder, prostate, and native voiding
- Pubic-symphysis debridement + primary fistula closure + vascularized flap interposition is the defining triad
- Rectus abdominis muscle flap (muscle-only, no skin paddle) is the Kaufman / Vanni default; omentum, gracilis, and perivesical fat are alternatives when rectus is unavailable
- 100% closure in the index series (n = 4) at 27 mo; 92% in the TURNS multicenter bladder-sparing arm (n = 12)
- Applicable to a narrow subset — localized anterior fistula, adequate bladder, viable sphincter, amenable defect
- 90% of irradiated patients develop subsequent bladder-outlet dysfunction even after successful fistula closure — counsel re: possible eventual urinary diversion
References
1. Kaufman DA, Browne BM, Zinman LN, Vanni AJ. "Management of radiation anterior prostato-symphyseal fistulas with interposition rectus abdominis muscle flap." Urology. 2016;92:122–126. doi:10.1016/j.urology.2016.01.029
2. Campbell JG, Vanni AJ. "Complex lower genitourinary fistula repair: rectourethral fistula and puboprostatic fistula." Urol Clin North Am. 2022;49(3):553–565. doi:10.1016/j.ucl.2022.04.012
3. Mundy AR, Andrich DE. "Urorectal fistulae following the treatment of prostate cancer." BJU Int. 2011;107(8):1298–1303. doi:10.1111/j.1464-410X.2010.09686.x
4. Eswara JR, Raup VT, Heningburg AM, Brandes SB. "Pelvic radiation is associated with urinary fistulae repair failure and need for permanent urinary diversion." Urology. 2015;85(4):932–936. doi:10.1016/j.urology.2014.11.051
5. Escandón JM, Kreutz-Rodrigues L, Fadel AE, et al. "Optimizing flap selection for urosymphyseal fistula repair: a comparative analysis of surgical outcomes." Microsurgery. 2026;46(3):e70197. doi:10.1002/micr.70197
6. Andrews JR, Hebert KJ, Boswell TC, et al. "Pubectomy and urinary reconstruction provides definitive treatment of urosymphyseal fistula following prostate cancer treatment." BJU Int. 2021;128(4):460–467. doi:10.1111/bju.15333
7. Robertson CN, Riefkohl R, Webster GD. "Use of the rectus abdominis muscle flap in urological reconstructive procedures." J Urol. 1986;135(5):963–965. doi:10.1016/s0022-5347(17)45938-6
8. Osterberg EC, Vanni AJ, Gaither TW, et al. "Radiation-induced complex anterior urinary fistulation for prostate cancer: a retrospective multicenter study from the Trauma and Urologic Reconstruction Network of Surgeons (TURNS)." World J Urol. 2017;35(7):1037–1043. doi:10.1007/s00345-016-1983-3
9. Kim E, Fernando C, McCombie A, et al. "Abdominal and perineal hernia rates following vertical rectus abdominis myocutaneous (VRAM) flap reconstruction — a supraregional experience." J Plast Reconstr Aesthet Surg. 2022;75(3):1158–1163. doi:10.1016/j.bjps.2021.11.002
10. Paprottka FJ, Krezdorn N, Lohmeyer JA, et al. "Plastic reconstructive surgery techniques using VRAM or gracilis flaps in order to successfully treat complex urogenital fistulas." J Plast Reconstr Aesthet Surg. 2016;69(1):128–137. doi:10.1016/j.bjps.2015.08.026
11. Raup VT, Eswara JR, Geminiani J, et al. "Gracilis muscle interposition flap repair of urinary fistulae: pelvic radiation is associated with persistent urinary incontinence and decreased quality of life." World J Urol. 2016;34(1):131–136. doi:10.1007/s00345-015-1597-1
12. Hwang A, Watson M, Talluri S, Okafor H, Singh A. "A novel perivesical fat rotational flap as an alternative to omental interposition in challenging urological reconstruction." Urology. 2023;182:e262–e263. doi:10.1016/j.urology.2023.08.023