Urethral stricture results when scarring narrows part of the urethra. Complications include a decrease in urine flow rate, frequent urination, urinary tract infections, and inflammation or infection of the prostate (prostatitis). Over time, these complications can lead to damage to kidney function, which may be irreversible.

URETHRAL ANATOMY

The Posterior Urethra
As the bladder is emptied during urination, the urine first passes through an opening called the bladder neck. The portion of the urethra the urine enters as the urine travels through the bladder neck is the prostatic urethra. Here, the urethra is surrounded by the prostate.

As the urine continues to travel toward the penis, it enters a short segment of the urethra called the membranous urethra. Here, the urethra is surrounded by a muscle called the external urinary sphincter. The voluntary contraction of the external sphincter allows a patient to stop voiding "midstream" once urination has been initiated. The prostatic urethra and the membranous urethra are together called the posterior urethra.

The posterior urethra is 3cm to 6cm (1 to 2 inches) long. Stricture disease of the posterior urethra is often caused by a urethral injury associated with a pelvic fracture, such as an automobile or industrial accident.

The Anterior Urethra
As the urine travels further toward the penis, it enters the bulbar urethra, the portion of the urethra between the sphincter area and the base of the penis (the portion of the penis that joins the scrotum and the abdomen). The urine then enters the penile urethra, which courses along the undersurface of the penis.

In the area of the beginning of the head of the penis, called the glans penis, the urine enters a portion of the urethra called the fossa navicularis. The urine then exits through the opening of the urethra at the tip of the glans penis, called the meatus. The bulbar and penile urethra, fossa navicularis, and meatus represent the anterior urethra. The anterior urethra is 18cm to 25cm (9 to 10 inches) long. The anterior urethra is surrounded by spongy tissue with a rich blood supply called the corpus spongiosus. This spongy tissue is enclosed by a tissue casing.

Urethral strictures that are not caused by pelvic injury most commonly occur in the anterior urethra. These strictures are usually associated with a process called spongiofibrosis, where the soft vascular spongy tissue surrounding the tissue develops scarring.

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