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Transperineal Gracilis Muscle Flap Interposition for Rectourethral Fistula

Transperineal gracilis muscle flap interposition (GMFI) is the most commonly used surgical approach for repair of acquired rectourethral fistula (RUF), with reported fistula closure rates of 84–100% depending on radiation history.[1][2][3] A 2013 systematic review of 416 RUF patients found that the transperineal approach (used in 66% of cases, predominantly with gracilis interposition) achieved an initial closure rate approaching 90%.[3]

For the broader RUF context see the male fistula treatment atlas; for fecal-diversion principles see Fecal Diversion; for the muscle flap atlas see Gracilis.

Etiology and Indications​

RUF most commonly arises from prostate cancer treatments — radical prostatectomy, EBRT and brachytherapy, cryotherapy, HIFU — and from pelvic trauma.[1][4] Patients present with pneumaturia, fecaluria, recurrent UTI, and passage of urine per rectum.[1]

Transperineal GMFI is indicated for:

  • Complex RUF that has failed conservative management or prior repair
  • Radiation-induced RUF — vascularized tissue interposition is critical when local tissue is poor
  • Large RUF or those with concurrent urethral stricture / bladder-neck contracture
  • RUF after pelvic-fracture urethral injury[5]

Rationale for Gracilis Interposition​

The gracilis is favored because it:

  • Provides well-vascularized tissue to a field often compromised by radiation or prior surgery
  • Has a reliable, long vascular pedicle (medial circumflex femoral artery) allowing tension-free transposition to the perineum
  • Is expendable with minimal donor-site morbidity (mild medial-thigh numbness is the main long-term complaint)[9]
  • Creates a physical barrier between urethral and rectal suture lines, reducing recurrence

Park 2022 — recurrence with gracilis vs without flap: 8% vs 50% (P = 0.009) without increased surgical complications.[10]

Surgical Technique​

The procedure is ideally performed by a multidisciplinary team (urologist + colorectal surgeon).[4][6]

1. Preoperative preparation​

Most patients undergo fecal diversion (diverting colostomy or ileostomy) and suprapubic catheter placement weeks-to-months before definitive repair to allow inflammation to subside and optimize local tissue.[7]

2. Positioning​

Exaggerated lithotomy.

3. Perineal approach​

Standard vertical midline perineal incision. The fistula tract is identified and completely excised. The rectum and urethra / bladder neck are carefully separated and dissected apart.[8]

4. Defect closure​

The rectal and urethral / bladder defects are closed separately in layers. When concurrent urethral stricture is present, a buccal mucosal graft onlay can reconstruct the urethra simultaneously.[2][7]

5. Gracilis flap harvest​

Through a separate longitudinal incision in the ipsilateral (usually left) medial thigh:

  • Dissect the gracilis from its fascia
  • Preserve the dominant vascular pedicle (medial circumflex femoral artery) entering the proximal third of the muscle
  • Divide the distal tendon[6][8]

6. Flap transposition​

Tunnel the pedicled gracilis subcutaneously from the thigh to the perineum and interpose between the urethral and rectal suture lines, fully covering both repairs.[8][9]

7. Wound closure​

Close the perineal wound over a drain.

Outcomes​

SeriesnEtiologySuccessFollow-upKey findings
Sbizzera 202221Prostate cancer95%27 mo (median)9% Clavien-Dindo ≥ 3b complications; 61% urinary incontinence; satisfaction 9/10[8]
Muñoz-Duyos 20179Post-prostatectomy (non-radiated)100%54 mo (median)No intraoperative or infectious complications; all stomas reversed except 1[6]
Vanni 20107435 non-radiated / 39 radiated100% non-radiated; 84% radiated20 mo (mean)31% of radiated patients required permanent fecal diversion[2]
Ghoniem 200825Prostate cancer100%28 mo (mean)72% urinary continence; 76% fecal continence[4]
Wexner 200836 (males)Prostate cancer78% initial / 97% overallNS36% had prior failed repairs; second gracilis successful in most[11]
Guo 201732Pelvic-fracture urethral injury91%33 mo (mean)100% in primary cases; 70% in re-do cases[5]
Park 202224 gracilis vs 12 controlMixed92% vs 50%≥ 30 dP = 0.009 for recurrence difference[10]

Garoufalia 2023 systematic review + meta-analysis (n = 658, gracilis interposition for complex perineal fistulas including RUF): weighted mean success 79.4% (95% CI 73.8–85%); short-term complication rate 25.7%; recurrence 16.7%.[12]

Impact of Radiation​

SettingClosureNotes
Non-radiated RUF~100%97% achieve bowel undiversion[2]
Radiation / ablation RUF~84%31% require permanent fecal diversion; higher wound infection, longer time to healing, lower stomal reversal (55% vs 91%)[2][13]

Radiation history and urinary incontinence are independent risk factors for fistula recurrence.[10]

Complications and Functional Outcomes​

  • Recurrence: 5–22% depending on series and radiation status[8][12]
  • Urinary incontinence: 61–75% postoperatively — often pre-existing damage from the original prostate cancer treatment rather than from the repair; some patients ultimately require AUS[4][7][8][14]
  • Fecal continence: generally preserved; mean St. Mark's 5/24; 76% maintain fecal continence[4][8]
  • Donor-site morbidity: minimal — mean lower-extremity functionality 2/20; mild medial-thigh numbness is the main complaint; no significant lower-extremity functional impairment[8][9]
  • Surgical complications: Clavien-Dindo ≥ 3b in 9–17% — thigh hematoma, urinoma, perineal wound infection[8][15]
  • Patient satisfaction: despite high urinary-incontinence rates, mean satisfaction 9/10[8]

Adjuncts and Alternatives​

  • Buccal mucosal graft — selectively used as a urethral patch onlay when concurrent urethral stricture is present, particularly in radiated patients[2][7]
  • Concurrent posterior urethroplasty — can be safely combined with RUF repair when there is associated urethral stenosis: 87% RUF closure with no isolated stricture recurrences (Khouri 2024)[7]
  • Alternative approaches — York-Mason (transsphincteric), transabdominal, transanal — but high-volume centers overwhelmingly favor transperineal + tissue interposition[3][13]
  • Alternative flaps — inferior gluteus muscle flap or other local flaps when the gracilis is unavailable[10][15]

Key Takeaways​

  • Gold standard for complex RUF repair at high-volume referral centers
  • Excellent fistula closure, low surgical morbidity, minimal donor-site impact
  • Best performed by a multidisciplinary team
  • Outcomes are significantly influenced by radiation history (~100% non-radiated → ~84% radiated)
  • Despite high postoperative urinary-incontinence rates (often pre-existing), patient satisfaction remains high

References​

1. Lo Re M, Pezzoli M, Garcia Rojo E, et al. "A systematic review on the surgical management of acquired rectourethral fistula." Int J Impot Res. 2026;38(3):214–225. doi:10.1038/s41443-025-01100-y

2. Vanni AJ, Buckley JC, Zinman LN. "Management of surgical and radiation-induced rectourethral fistulas with an interposition muscle flap and selective buccal mucosal onlay graft." J Urol. 2010;184(6):2400–2404. doi:10.1016/j.juro.2010.08.004

3. Hechenbleikner EM, Buckley JC, Wick EC. "Acquired rectourethral fistulas in adults: a systematic review of surgical repair techniques and outcomes." Dis Colon Rectum. 2013;56(3):374–383. doi:10.1097/DCR.0b013e318274dc87

4. Ghoniem G, Elmissiry M, Weiss E, et al. "Transperineal repair of complex rectourethral fistula using gracilis muscle flap interposition — can urinary and bowel functions be preserved?" J Urol. 2008;179(5):1882–1886. doi:10.1016/j.juro.2008.01.021

5. Guo H, Sa Y, Fu Q, Jin C, Wang L. "Experience with 32 pelvic fracture urethral defects associated with urethrorectal fistulas: transperineal urethroplasty with gracilis muscle interposition." J Urol. 2017;198(1):141–147. doi:10.1016/j.juro.2017.01.071

6. Muñoz-Duyos A, Navarro-Luna A, Pardo-Aranda F, et al. "Gracilis muscle interposition for rectourethral fistula after laparoscopic prostatectomy: a prospective evaluation and long-term follow-up." Dis Colon Rectum. 2017;60(4):393–398. doi:10.1097/DCR.0000000000000763

7. Khouri RK, Accioly JPE, DeWitt-Foy ME, Wood HM, Angermeier KW. "Posterior urethral reconstruction at the time of rectourethral fistula repair: technique and outcomes." Urology. 2024;186:36–40. doi:10.1016/j.urology.2024.02.026

8. Sbizzera M, Morel-Journel N, Ruffion A, et al. "Rectourethral fistula induced by localised prostate cancer treatment: surgical and functional outcomes of transperineal repair with gracilis muscle flap interposition." Eur Urol. 2022;81(3):305–312. doi:10.1016/j.eururo.2021.09.017

9. Zmora O, Potenti FM, Wexner SD, et al. "Gracilis muscle transposition for iatrogenic rectourethral fistula." Ann Surg. 2003;237(4):483–487. doi:10.1097/01.SLA.0000059970.82125.DB

10. Park KM, Rosli YY, Simms A, et al. "Preventing rectourethral fistula recurrence with gracilis flap." Ann Plast Surg. 2022;88(4 Suppl 4):S316–S319. doi:10.1097/SAP.0000000000003085

11. Wexner SD, Ruiz DE, Genua J, et al. "Gracilis muscle interposition for the treatment of rectourethral, rectovaginal, and pouch-vaginal fistulas: results in 53 patients." Ann Surg. 2008;248(1):39–43. doi:10.1097/SLA.0b013e31817d077d

12. Garoufalia Z, Gefen R, Emile SH, et al. "Gracilis muscle interposition for complex perineal fistulas: a systematic review and meta-analysis of the literature." Colorectal Dis. 2023;25(4):549–561. doi:10.1111/codi.16427

13. Hanna JM, Turley R, Castleberry A, et al. "Surgical management of complex rectourethral fistulas in irradiated and nonirradiated patients." Dis Colon Rectum. 2014;57(9):1105–1112. doi:10.1097/DCR.0000000000000175

14. Samplaski MK, Wood HM, Lane BR, et al. "Functional and quality-of-life outcomes in patients undergoing transperineal repair with gracilis muscle interposition for complex rectourethral fistula." Urology. 2011;77(3):736–741. doi:10.1016/j.urology.2010.08.009

15. Oner M, Tsay AT, Abbas MA. "The use of the gracilis flap in colorectal surgery: surgical technique, results, and review of the literature." Int J Colorectal Dis. 2025;40(1):133. doi:10.1007/s00384-025-04928-4