Posterior Urethral Stricture

Posterior urethral stricture is narrowing of the prostatic or membranous urethra, including the vesicourethral anastomosis and bladder neck.

The main causes are pelvic fracture urethral distraction defects, vesicourethral anastomotic stenosis after radical prostatectomy (roughly 1 to 10% in most series), bladder neck contracture after transurethral prostate surgery, and radiation or brachytherapy.

It is more difficult to repair than anterior stricture because of the nearby sphincter and the effect on continence and erection.

Pathophysiology. After pelvic fracture, the membranous urethra is torn and the gap fills with fibrous tissue. After surgery or radiation, ischaemia and fibrosis narrow the anastomosis or bladder neck.

Radiation also impairs vascularity, which lowers success of all treatments.

Weak stream, straining, retention, recurrent infection, and haematuria. Urinary leakage from a competent bladder neck or sphincter may appear after treatment. Pelvic fracture patients may have erectile dysfunction from the injury itself. Ask about timing after surgery, radiation dose and previous endoscopic treatment.

• Uroflowmetry, residual urine, urine culture, creatinine, renal ultrasound.
• Cystoscopy to assess the scar, the bladder neck and the continence mechanism.
• Combined antegrade (through a suprapubic tract) and retrograde urethrography with a simultaneous view to define the gap length and alignment. MRI helps in complex pelvic fracture cases.
• Assess the bladder neck competence and sphincter function, because these decide the risk of incontinence after repair.
• Assess erectile function and prior radiation.

Differential diagnosis.

• Benign prostatic enlargement
• Bladder neck obstruction
• Anterior urethral stricture
• Detrusor underactivity
• Recurrent prostate cancer at the anastomosis
• Stone or foreign body
• Urethral false passage

• Retention: suprapubic catheter.
• Anastomotic stenosis or bladder neck contracture: cold knife incision or resection at 12 o'clock, with mitomycin C 0.4 mg/mL injected into the scar edges in published series, which lowers recurrence. Repeat endoscopic treatment is limited to 2 attempts, because each cut raises the risk of incontinence, particularly after radiation.
• Intermittent self-catheterisation with a 12 to 16 Fr catheter after incision, for weeks to months, to keep the lumen patent.
• Pelvic fracture distraction defect: delay repair for at least 3 months after injury, then perineal anastomotic urethroplasty. Success about 90 to 95% in specialist units. Extra steps for gaps include corporal splitting, inferior pubectomy and urethral rerouting.
• Recurrent or complex post-prostatectomy stricture: open or robotic reconstruction with flap or graft. Artificial urinary sphincter can follow if incontinence develops, usually after at least 3 months of stability.
• Radiation strictures: avoid repeated incision, and consider urinary diversion when repair fails.

Monitoring. Uroflowmetry at 3, 6 and 12 months, and continence and erectile function assessment. Pericatheter urethrogram before catheter removal after urethroplasty.

Referral and escalation. Refer early to a reconstructive urologist with experience in posterior urethral repair. Urgent referral for retention, infection or renal impairment.