How to manage posterior urethral strictures

Key Points

The most common cause of posterior strictures (not all of which are truly "posterior"; see below) is the posterior urethral distraction defect (PUDD). The management of PUDDs can be quite challenging. If handled incorrectly, they may result in debilitating morbidities, including incontinence, impotence, and recurrent stricture disease.^1,2 Because only 4% to 14% of pelvic fractures result in posterior urethral distraction injuries, the vast majority of urologists lack experience with this diagnosis. Therefore, it is imperative that a correct diagnosis is made and proper therapy instituted. With thorough preoperative evaluation, appropriate surgical planning, and adherence to basic surgical principles, success rates exceeding 90% are achievable.

Anatomic relationships

The anterior urethra contains the fossa navicularis, the bulbar, and pendulous portions of the urethra, while the posterior urethra contains the membranous portion, the prostatic portion, and the bladder neck. The urogenital diaphragm, the bladder neck, and the prostatic urethra are all important in maintaining continence.¹

Two portions of the urethra are fixed to the bony pelvis: the puboprostatic ligaments attach the prostatic urethra to the pubic symphysis, and the urogenital diaphragm fixes the membranous urethra to the ischiopubic rami.^1,3 When high-velocity pelvic trauma occurs, the fixed portions of the urethra move as a unit superiorly and then posteriorly, resulting in a shear force that distracts the bulbar and membranous urethra.^1,4,5

We must clarify that most urethral distraction injuries are neither posterior (ie, proximal to the rhabdosphincter) nor true "strictures." Modern nomenclature favors the term "posterior urethral distraction defect" (PUDD), despite the fact that we and others have shown that most (80%) are located distal to the rhabdosphincter.⁶

Diagnosis

In one study of 191 men with urethral distraction injuries, 95% had either one of these serious pelvic fractures and only 5% had more simple pelvic fractures. High-velocity collisions, falls from great heights, or industrial accidents are likely culprits.^1,5,9 These injuries are associated with a concomitant bladder rupture 17% of the time.⁹