Antibiotic prophylaxis for urinary tract infection after midurethral sling: a randomized controlled trial.

Because of the reported high percentage of bladder infections after placement of a midurethral sling (8.9%-34%), this study was undertaken to determine if a 3-day postoperative course of a urinary antibiotic would significantly lower the incidence of urinary tract infection (UTI) among treated women. Women who were planning outpatient vaginal surgery for stress incontinence were enrolled, after informed consent, and randomized to receive placebo or nitrofurantoin (100 mg 2 times a day) for 3 days after surgery. Research subjects and investigators were blinded to the randomization. Women were observed for signs and symptoms of UTI until 6 weeks after surgery. Sample size was calculated to have 80% power to detect a 15% difference in the primary outcome (α = 0.05). The primary outcome was analyzed using a χ analysis. Data were analyzed from 149 subjects (placebo, n = 75; drug, n = 74). Overall, 37 women (24.8%) were diagnosed with a UTI during the study period. The incidence of postoperative UTI was significantly lower in the treatment arm (17.6%) then in the placebo arm (32%; P = 0.04). A short (3-day) course of nitrofurantoin after outpatient sling surgery significantly reduces the incidence of postoperative bladder infection in the first 6 weeks after sling surgery.