The etiology of urinary retention after surgery for genuine stress incontinence.

Transient postoperative urinary retention after stress incontinence surgery is common, and there is no widely accepted method of hastening the return to normal voiding. The etiology of this retention is poorly understood. Failure of the relaxation of the striated external urethral sphincter has been proposed as an etiologic agent, but has not been documented. Ten patients about to undergo a Burch colposuspension or sub-urethral sling, who demonstrated normal preoperative voiding, were recruited to a study of postoperative retention. Hook-wire electromyographic (EMG)probes were placed into the external urethral sphincter while the patients were under anesthesia, and a suprapubic catheter was placed. We performed instrumented voiding trials 1 or 2 days after surgery while continuously recording urethral EMG and intravesical pressure. Two patients demonstrated normal voiding. Two patients were able to void but demonstrated no EMG silencing. Six patients were unable to void and demonstrated persistent EMG activity. Four of these demonstrated no detrusor contraction, whereas two demonstrated detrusor contractions. All patients resumed normal voiding by clinical parameters within 14 days of surgery. Our study supports other research that suggests that failure of relaxation of the striated urethral sphincter contributes to postoperative urinary retention.