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

Objective: 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.

Methods: 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.

Results: 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).

Conclusions: 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.