Urethral False Passage

A urethral false passage is an artificial channel created in the urethral wall or surrounding tissue when a catheter, sound, dilator or endoscope leaves the true lumen under pressure. It is almost always iatrogenic and follows force against a narrowed, distorted or obstructed urethra.

The commonest sites are the bulbar urethra just proximal to a stricture, the bulbomembranous junction where the urethra angles, and the floor of the prostatic urethra behind an enlarged median or lateral lobe.

Pathophysiology. The instrument tip is deflected by scar or prostatic tissue and tunnels through mucosa and spongiosum. Urine then dissects along the tract, causing extravasation, infection and periurethral abscess.

Healing produces spongiofibrosis and a later stricture, and the tract can complicate subsequent urethroplasty or prostate surgery.

Risk factors: urethral stricture, prostatic enlargement, previous urethral surgery or radiotherapy, blind catheterisation by inexperienced staff, balloon inflation within the urethra, and self-catheterisation with a stiff or ill fitting catheter.

Urethral bleeding after instrumentation, sudden pain with loss of the normal resistance during passage, a catheter that drains blood but no urine despite a distended bladder, a catheter lying at an abnormal angle, and perineal or scrotal haematoma. Later features are fever, dysuria, recurrent catheter blockage, periurethral abscess and stricture.

A failed or traumatic catheterisation is the usual history. A large posterior tract may perforate the rectum, so ask about rectal bleeding and faecaluria.

• Stop all blind attempts as soon as resistance, pain or bleeding occurs.
• Retrograde urethrography with 20 to 30 mL of water soluble contrast and oblique views. The false passage appears as a channel running beside or away from the lumen, and extravasation shows as contrast in periurethral tissue.
• Flexible urethroscopy by an experienced operator, using low pressure irrigation, shows the true lumen, the false passage entrance and the stricture or obstruction.
• Bladder and pelvic ultrasound for retention and haematoma. Urine culture, creatinine, and full blood count if bleeding is heavy.
• MRI or CT of the pelvis if abscess or rectal communication is suspected.

Differential diagnosis.

• Urethral stricture with bleeding
• Anterior or posterior urethral injury from trauma
• Urethral perforation by a stone or foreign body
• Bladder rupture
• Prostatic bleeding after catheter trauma
• Periurethral abscess
• Urethral diverticulum

• Do not force a catheter again. Do not use a stiff stylet. Inflate the balloon only after urine drains.
• Retention: suprapubic catheter of 12 to 16 Fr, placed under ultrasound control once the bladder is distended. This avoids further handling of the injured urethra.
• When a urethral catheter is still needed, use flexible cystoscopy to pass a wire through the true lumen into the bladder and place a 12 to 16 Fr silicone catheter over it. Leave it for 7 to 14 days, up to 3 weeks if extravasation or a large tract was shown, and perform a pericatheter urethrogram before removal.
• Antibiotics: a single dose directed by the latest culture, or ceftriaxone 1 g intravenously once if no culture exists. Established periurethral infection needs drainage and a culture directed course of 7 to 14 days.
• Small tracts with the catheter in the true lumen usually heal without further treatment.
• Treat the underlying obstruction (stricture, prostatic enlargement) at 3 months or more after healing. Do not dilate through the old tract.

Monitoring. Uroflowmetry at 3 and 12 months for stricture formation, and urine culture if symptomatic.

Referral and escalation. Refer any failed catheterisation with bleeding. Urgent referral for retention, sepsis, periurethral abscess or suspected rectal communication.