Vesicocutaneous Fistula

Vesicocutaneous fistula is an abnormal tract between the bladder and the skin, most often on the lower abdominal wall, suprapubic region, groin or umbilicus.

Causes are previous surgery (cystotomy, suprapubic catheter tract, caesarean section, hysterectomy, hernia repair with mesh, appendicectomy, bowel and urachal surgery), radiotherapy, trauma, infection (tuberculosis, actinomycosis), Crohn disease, bladder cancer, bladder diverticulum, foreign body including eroded mesh, and congenital patent urachus (vesicoumbilical).

Pathophysiology. A defect in the bladder wall, kept open by infection, foreign material, malignancy, radiation ischaemia or distal obstruction (urethral stricture, prostatic obstruction, neurogenic bladder), allows urine to track along the surgical or infected path to the skin.

Continuous or intermittent leakage of urine through a wound or sinus, skin excoriation, pain, fever, recurrent urinary infection, and haematuria. Leak is often worse on voiding or with a full bladder. Check for previous surgery, radiotherapy, mesh, catheter, Crohn disease and voiding symptoms.

• Compare the creatinine of the leaking fluid with serum creatinine. Fluid creatinine well over the serum value confirms urine.
• Methylene blue instilled into the bladder emerging at the skin opening.
• Sinogram or fistulogram, and CT cystography with post-drain images.
• Cystoscopy with biopsy of the fistula site and any suspicious mucosa.
• CT or MRI of the pelvis for abscess, mesh, bowel involvement and malignancy.
• Voiding studies and uroflowmetry for distal obstruction, urine culture, and creatinine.

Differential diagnosis.

• Wound infection with serous discharge
• Ureterocutaneous fistula
• Enterocutaneous fistula
• Urinoma or lymphocele with sinus
• Urachal cyst or sinus
• Tuberculous sinus

• Control sepsis with drainage of collections and a culture directed antibiotic. Protect the skin with barrier cream and collecting appliances.
• Relieve distal obstruction and drain the bladder with a urethral or suprapubic catheter of 12 to 16 Fr. Small non-irradiated fistulae with no foreign body or malignancy may close after 4 to 6 weeks of drainage.
• Failure to close, or the presence of mesh, malignancy or radiation change: surgical repair. Excise the tract, close the bladder in two layers with absorbable suture, interpose healthy vascularised tissue (omentum or rectus flap), remove any foreign body, drain the space, and close the skin without overlapping suture lines.
• Catheter for 10 to 14 days, up to 3 weeks after complex repair, with cystography before removal.
• Patent urachus or urachal remnant: excise the whole remnant with a cuff of bladder dome, because of the small risk of urachal adenocarcinoma in adults.
• Malignant or tuberculous fistula: treat the underlying disease.
• Irradiated fistulae often need interposition and sometimes permanent diversion.
• Perioperative antibiotic: a single dose directed by culture, or cefazolin 2 g intravenously once (3 g if over 120 kg).

Monitoring. Cystography before catheter removal, then review for leakage, urinary infection and voiding at 6 weeks and 3 months.

Referral and escalation. Refer to urology, with colorectal or gynaecological input where relevant. Urgent referral for sepsis, mesh erosion or suspected cancer.