A placebo controlled double blind study using perioperative prazosin in the prevention of urinary retention following inguinal hernia repair.

Acute urinary retention is a frequent complication following inguinal hernia repair. The smooth muscle of the bladder neck and the prostate have been demonstrated to be rich in alpha-1 adrenergic receptors. It has been postulated that the aetiology of acute urinary retention postoperatively is at least partially due to adrenergic stimulation; blocking these receptors may reduce the incidence of acute urinary retention. We have used prazosin in a double blind, placebo controlled study to establish its efficacy in the prevention of acute urinary retention in patients undergoing elective inguinal hernia repair. A total of 70 male patients were enrolled; 36 patients had been allocated active drug and 34 patients had been allocated placebo. Only two patients developed acute urinary retention. Both patients had been allocated prazosin and had received a general anaesthetic for their hernia surgery. In either arm of the study, a higher number of patients developing urinary retention would have been expected but this may be explained by the greater vigilance on urinary output by nursing staff aware that the trial was being conducted. On the basis of our findings, we do not recommend the routine use of perioperative prazosin with inguinal hernia repair. Further studies in high risk groups would be necessary to assess more fully the efficacy of prazosin in this situation.