Urethral Fistula

Urethral fistula is an abnormal communication between the urethra and another structure or surface. Types include urethrorectal, urethrovaginal, urethroperineal, urethroscrotal, urethrocutaneous and prostatic cavity fistulae.

Causes are trauma, surgery (radical prostatectomy, hypospadias repair, transurethral resection, urethroplasty), radiation (external beam, brachytherapy) and ablative energy treatment, infection (periurethral abscess, tuberculosis, schistosomiasis), malignancy, inflammatory bowel disease and, in women, obstructed labour.

Rectourethral fistula is rare after radical prostatectomy (under 1% in most series) but more frequent after combined radiation and ablation.

Pathophysiology. Tissue ischaemia, infection or direct injury creates a tract between two epithelialised surfaces, kept open by urine flow, distal obstruction and poor local blood supply.

Radiated tissue heals poorly, which makes repair harder.

Urine leaking through the abnormal opening during voiding, pneumaturia, faecaluria and passage of urine from the rectum in rectourethral fistula, recurrent urinary infection, epididymo orchitis, perineal pain and sepsis. Check history of surgery, radiation and Crohn disease. Examine the perineum, scrotum, vagina and rectum.

• Urine culture, creatinine, and inflammatory markers if septic.
• Methylene blue instilled into the bladder with a tampon or dressing test, or dye injection into the tract.
• Retrograde urethrography with voiding cystourethrography, and antegrade study when a suprapubic catheter is in place.
• Cystourethroscopy, and proctoscopy or colonoscopy for rectal communication.
• MRI of the pelvis defines tract, abscess and its relation to the sphincter.
• Examination under anaesthesia with biopsy of the tract when cancer recurrence or Crohn disease is possible.

Differential diagnosis.

• Vesicovaginal or vesicorectal fistula
• Enterovesical fistula
• Periurethral abscess with tract
• Urethral diverticulum with discharge
• Anal fistula
• Urinary incontinence from other causes

• Control sepsis: drain collections and give antibiotics directed by culture.
• Urinary diversion by suprapubic catheter, with faecal diversion by colostomy for rectourethral fistula that is large, radiated, infected or contaminated by stool.
• Small fistulas without radiation may close with catheter drainage for several weeks (about 6 to 12). If they do not close, proceed to repair.
• Delay definitive repair by about 3 months to allow inflammation to settle, and optimise nutrition and glycaemic control.
• Repair principles: excise the tract, close each layer separately with no overlapping suture lines, interpose healthy vascularised tissue (dartos, gracilis muscle, omentum, tunica vaginalis, or a buccal graft for the urethra), and treat any distal obstruction.
• Approach for rectourethral fistula: transanal advancement flap, transperineal with interposition, trans-sphincteric posterior approach, or abdominoperineal. Radiated fistulae need interposition and often permanent diversion.
• Remove the urethral catheter after a pericatheter urethrogram confirms healing, usually at 3 to 4 weeks.

Monitoring. Contrast study before catheter removal and before colostomy reversal, then urine culture, uroflowmetry and symptom review.

Referral and escalation. Refer to urology and colorectal surgery. Urgent referral for sepsis, faecal contamination of the urinary tract or necrotising infection.