Rectourethral Fistula

Fourth chapter of Part II ("Anorectal Disease"). An uncommon but potentially devastating, QoL-impacting condition — distinct from the cryptoglandular fistulas covered on Anal Fistula in both etiology (overwhelmingly iatrogenic, male-specific) and anatomy (a communication between the rectum and the posterior urethra rather than a sphincter-complex tract). This chapter covers acquired rectourethral fistula (RUF) in adults only — congenital RUF is typically found/treated in the neonatal period and is out of scope.

Etiology

The vast majority of acquired RUF are iatrogenic, following prostate cancer treatment — multimodal treatment more often than any single modality. The prostatic urethra is separated from the anterior rectal wall only by Denonvilliers' fascia and the prostate capsule, making it vulnerable to damage/fistulization.

Radical prostatectomy: complicates 1–6% of cases regardless of open, laparoscopic, or robotic approach. Reported rectal-injury incidence at prostatectomy: 0.1–9%; in one review, 54% of patients who developed RUF had an overt rectal injury at the index operation. Most RUFs result from unrecognized rectal injury or failed rectal repair, typically at the vesicourethral anastomosis. Other risk factors: age, prior transurethral resection of the prostate, bacterial prostatitis, previous hormonal therapy, and a perineal operative approach.
Radiation: contributes significantly to RUF formation via ionizing-radiation microvascular injury, mucosal ischemia, and tissue fibrosis. Radiotherapy involvement in RUF cases rose sharply over time — <4% before 1997 vs. >50% from 1998–2012. As stand-alone primary therapy: ~1% RUF rate for external beam radiotherapy (EBRT), ~3% for brachytherapy; combining both modalities increases risk regardless of order/isotopes used. Newer modalities (cryosurgery, high-intensity focused ultrasound/HIFU) carry ~2% RUF risk currently.
Salvage therapy (prostatectomy, cryosurgery, HIFU, or brachytherapy for biopsy-confirmed recurrence after EBRT) carries markedly higher RUF incidence and complexity — reported rates 3% to as high as 60%. These RUFs tend to be among the most complex, with large fibrotic connections in a field of poor-quality tissue; concomitant urethral/rectal strictures and sexual/urinary dysfunction are common.
Other causes: inflammatory bowel disease and pelvic infections can cause primary RUF, though far less frequently than iatrogenic/radiation causes — see Crohn Disease for that page's existing perianal Crohn's fistula content; this chapter explicitly defers RUF-specific Crohn's management to the Crohn's-specific literature. Traumatic pelvic injury (vehicular trauma, pelvic fracture, battle-related penetrating perineal injury) can also cause RUF, often requiring complex, staged repair over months. Iatrogenic RUF may also follow low rectal resection for rectal cancer (see Rectal Cancer) or salvage resection for anal cancer, particularly in patients who received pelvic radiation — secondary rectal cancer following EBRT for prostate cancer is itself a recognized long-term concern (occurring 5–15 years post-treatment), and anteriorly-directed rectal biopsies in that setting can precipitate RUF formation. Rarely, elective rectal/anal surgery (fistulotomy, stapled hemorrhoidopexy — see Anal Fistula and Hemorrhoids) can also lead to RUF.

Clinical presentation

Post-prostatectomy RUF typically presents in the first 2–4 weeks after surgery. Radiation-associated RUF can present much later — up to 14 years after the last radiotherapy dose — reflecting the long-standing nature of radiation tissue damage. Symptoms: fecaluria, pneumaturia, pelvic/bladder pain, passage of urine per rectum on attempted urination, recurrent UTIs. Preexisting erectile dysfunction is very common (>80% in one series) given the shared pelvic-nerve injury mechanism with the causative prostate procedure.

Diagnostic evaluation

Exam often reveals a defect in the anterior rectal wall 5–6 cm from the anal verge. Direct visualization via cystoscopy and colonoscopy establishes tract location/size and surrounding tissue quality, and allows biopsy of any area suspicious for recurrent malignancy. Voiding cystourethrography or Gastrografin enema may add information; axial imaging (CT/MRI) is a useful adjunct especially when other modalities are equivocal. Urodynamic evaluation of urinary functional status is recommended when feasible — patients with severe underlying incontinence or voiding dysfunction are unlikely to see significant improvement after RUF repair and may be better served by primary permanent urinary diversion instead.

Classification

Two schemas are used:

Rivera et al. staging (by location, size, patient history) — not universally adopted: Stage 1 (<4cm from the anal verge, nonirradiated), Stage 2 (>4cm from the anal verge, nonirradiated), Stage 3 (<2cm-diameter fistula regardless of distance, prior radiation), Stage 4 (>2cm-diameter fistula regardless of distance, prior radiation), Stage 5 (ischial decubitus fistula).
Simple vs. complex (used by most other authors): simple RUF are small (<1cm), nonirradiated, with minimal symptoms and no associated sepsis or previous repair attempt; complex RUF are larger (>1cm) with complicating factors — previous radiation/cryotherapy, urethral stricture, sepsis, or a previous failed repair.

Management

Depends on fistula size/etiology and the managing team's familiarity with a given approach. If a neoplasm is the cause, its management takes precedence; if Crohn's disease is the cause, medical management must be optimized before any fistula intervention is attempted (readers directed to the Crohn's-specific literature — see Crohn Disease).

RUF is best managed by a multidisciplinary team (colorectal surgeon, urologist, often a reconstructive/plastic surgeon). After initial assessment, patients fall into simple or complex groups. A significant number of RUF patients heal without surgical intervention — a spontaneous closure rate of 14–46% was reported after fecal diversion alone, and some patients with a small RUF heal with urethral catheter drainage alone.

Simple RUF (often seen after laparoscopic/robotic prostatectomy): initial management is urethral catheter drainage for 2–3 months. If healed, the catheter is simply removed. If unhealed, local flap repair is indicated (fecal diversion not required for this step). If local flap repair fails, fecal diversion follows. If the fistula remains unhealed after 2–3 months of diversion, repair proceeds via repeat local flap repair or a transperineal approach with gracilis or dartos muscle interposition.
RUF from external traumatic injury: most often complex; managed initially with fecal diversion and often suprapubic bladder drainage to minimize symptoms, abdominopelvic imaging to assess for pelvic abscess (drained if present), and reassessment at 3 months.
If RUF remains unhealed after diversion and the patient is a poor operative candidate or declines further surgery, permanent diversion is a reasonable option to manage symptoms.

Transanal approach

Endorectal advancement flap — a good option for simple RUF; requires absence of anal/rectal stricture, and fecal diversion is not required. Technique detail is shared with Anal Fistula's ERAF description (technique originally described in that chapter); can also be performed via a TEM platform. Small fistulas rarely need urethral augmentation; pliable normal tissue (pararectal fat) can be interposed over the urethral opening, sometimes reinforced with biologic mesh. Urethral catheter maintained 4–6 weeks before assessing healing.

Transperineal approach

The preferred approach for RUFs requiring interposition of healthy, well-vascularized tissue — successful closure rates ~90% regardless of radiation/ablative-therapy history. Good exposure for low and mid-rectal RUFs. Performed prone jackknife, U-shaped perineal incision.

Dartos muscle flap — adequate tissue bulk/reach for low, small RUFs. Urethral tissue may be augmented with buccal mucosa or biologic mesh if needed; urethral and rectal defects closed separately (horizontal rectal closure preferred to minimize luminal narrowing) before the dartos flap is rotated/parachuted into the dissected space between the repairs and secured. One series (8 patients, half with a prior repair attempt, all with fecal + urethral/suprapubic diversion): 75% healed without complication.
Gracilis muscle flap — preferred for larger, higher, or radiated RUFs. The gracilis is harvested from the medial thigh (external tracing ~4cm posterior to the adductor muscle, care to preserve the major neurovascular bundle within 10cm of the pubic symphysis), tunneled subcutaneously into the perineum, and parachuted into the dissected perineal space alongside the rectal/urethral repairs.

Posterior approach

Used historically, overall success ~88% (similar to transperineal), but most posterior-approach data comes from nonirradiated patients, and its use has declined significantly over the last 15 years — fistulas are now generally more complex, and posterior approaches have limited exposure, can't concurrently manage urethral stricture/bladder neck issues, and offer limited interposition-flap use.

York-Mason technique: posterior sagittal division of the anal sphincters, levators, and posterior rectal wall, exposing the anterior rectal wall/fistula; fistula divided, urethra then rectum repaired, incision closed in layers. Major complications: rectocutaneous fistula, sphincter compromise.
Kraske technique: parasacral incision, coccygeal resection, division of the anococcygeal ligament to expose the posterior rectal wall, which is opened to expose the anterior rectal wall/fistula; repair proceeds as above.

Transabdominal approach

Best suited for RUF with concomitant complex intrapelvic problems not addressable perineally or posteriorly — positive oncologic margins after prostatectomy, nonfunctional bladder, stricture urethra, or failed prior repair attempt. Options tailored to the specific situation: cystectomy with urinary diversion plus rectal repair, proctectomy with coloanal anastomosis, abdominoperineal resection, pelvic exenteration. Rectal preservation vs. proctectomy requires careful consideration — a second attempt at low pelvic dissection/repair carries much higher failure risk than the initial attempt. If rectal tissue is healthy, the fistula isn't overly large, and healthy interposition tissue is available, omentum or rectus interposition repair is a good choice (urinary procedure done first; omentum mobilized preserving the left gastroepiploic artery, parachuted anterior to the rectal repair). If rectal tissue quality is poor or the defect too large, proctectomy ± coloanal anastomosis is indicated (stapled or, for very low fistulas, mucosectomy/intersphincteric dissection with handsewn anastomosis); if sphincter preservation isn't indicated, an end colostomy avoids perineal-incision morbidity.

Other approaches

Small-patient-number reports appear periodically: bilateral puborectalis interposition (4 patients, all healed at median 8 months); fibrin glue (anecdotal, low-risk attempt in poor surgical candidates); fistula cauterization and large over-the-scope clips (short follow-up reported) — none have entered mainstream RUF management.

Outcomes of RUF repair

Highly variable across the literature — nearly all reports are case series (no RCTs exist given the condition's rarity), and patient selection clearly influences outcomes. Reported overall fistula closure rate after repair: 68–100%. Closure of intestinal/urinary diversion is significantly less likely in radiated patients.

Transanal approach: safe/effective for small, low (by definition nonirradiated) RUFs. One series (12 patients, rectal advancement flap): 67% primary healing (8/12); 2 of 4 recurrences underwent successful second repair for an 83% final success rate. Initial closure rate with a transperineal approach was 90%; the flap used most commonly was the gracilis. Gracilis-flap outcomes reflect the current standard of care.
Transperineal with muscle interposition — the current procedure of choice for complex RUF without concomitant intrapelvic complications. Good results reported with dartos flap (75% healing); gracilis is the most commonly used flap. A large systematic review found essentially equivalent postop RUF healing in nonradiated vs. radiated patients (89% vs. 90%), but permanent fecal diversion was 25% in radiated vs. 4% in nonradiated patients, and permanent urinary diversion was 42% vs. 4% — radiation doesn't reduce the chance of eventual fistula closure so much as it dramatically increases the chance that diversion, once placed, becomes permanent. Multiple further case series corroborate radiation as the dominant driver of poorer functional/ diversion outcomes (e.g. 98% nonradiated vs. 86% radiated healing at median 14.5-month follow-up in a 98-patient series; 100% healing with gracilis interposition vs. 29% without, in a small radiated cohort).
Posterior (York-Mason) approach: adding muscle interposition improves healing, and radiation is again associated with poorer outcome. A 14-patient nonradiated York-Mason series: all healed except a single Crohn's patient who recurred at 11 years. A 20-patient York-Mason series (2002–2016): 90% initial success; diabetes, smoking, and irradiation history were associated with failure. A 28-patient series (2008–2018): 64% initial success, 75% ultimate success — 89% in nonirradiated vs. 50% in irradiated patients; outcomes markedly improved with gracilis interposition (100% healing with vs. 29% without).

Conclusion

Adult-acquired RUF is a complex, relatively rare condition, most commonly caused by multimodality prostate cancer treatment (rectal cancer treatment and traumatic injury are less common but important causes). Simple RUFs do well with diversion alone or local flap management without fecal diversion. Complex RUFs need a multidisciplinary approach; the transperineal approach with muscle interposition flap is most often used and gives the best outcomes. There's no evidence that fecal diversion improves closure rate above and beyond flap repair itself — its use is guided by surgeon judgment and clinical reasoning (favored for large, complex, symptomatic RUF, or medical comorbidities raising infectious-complication risk). A diverting loop ileostomy is favored by some authors for its relative ease of construction/closure, leaving the colon available should a more extensive procedure (proctectomy with low anastomosis) become necessary. Radiated patients face persistently higher repair-failure risk and higher risk that fecal/urinary diversion becomes permanent; gracilis-harvest-related complications, while uncommon, are not inconsequential.

Anal Fistula — the ERAF technique used for simple RUF repair is shared with (and originally described in) that page's cryptoglandular-fistula content.
Crohn Disease — a rare non-iatrogenic RUF etiology; this chapter explicitly defers to Crohn's-specific management principles rather than covering RUF-in-Crohn's in its own right.
Rectal Cancer — low rectal resection and pelvic radiation as RUF risk factors; secondary rectal cancer as a recognized long-term complication of prostate EBRT.
Colorectal Anastomotic Complications — shares radiation/pelvic-fibrosis mechanistic themes with that page's chronic presacral sinus tract content, though the two are distinct entities (a posterior anastomotic leak sequela vs. a urethral fistula).
Hemorrhoids — stapled hemorrhoidopexy as a rare elective-surgery cause of RUF.

Open items / gaps

No primary-literature source yet for any cited series — all case-series/systematic-review data known only via this textbook chapter's synthesis; genuinely limited by RUF's rarity (the chapter itself notes no RCTs exist).
Rectovaginal fistula (the female-anatomy analog) now has its own dedicated page — see Rectovaginal Fistula (ASCRS Ch15).

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