Does alpha sympathetic blockade prevent urinary retention following anorectal surgery?

Urinary retention is the most common complication after anorectal surgery, with rates as high as 52 percent reported. With the trend toward early discharge, avoidance of this complication is particularly important. Perioperative fluid restriction and the use of short-acting anesthetics have been shown to be effective in decreasing postoperative urinary retention rates but are not applicable in all cases. Reflex sympathetic stimulation, possibly as a result of perianal pain, may lead to increased muscular tone of the internal sphincter at the bladder neck. This theory had led to the effective use of alpha-adrenergic blockade in the treatment of established cases of urinary retention after anorectal surgery, herniorrhaphy, and major pelvic surgery. However, the prophylactic role of alpha blockade after anorectal surgery has not been studied. In a double-blind, prospective, randomized study, 51 patients were treated with either prazosin and alpha-adrenergic blocker or placebo prior to and immediately after elective anorectal surgery. Urinary retention rates were similar in the two groups. At this time, prophylactic alpha-adrenergic blockade is not recommended for the prevention of urinary retention after anorectal surgery.