Value of urinary prophylaxis with methenamine in gynecologic surgery

There is a high risk of postoperative bacteriuria and urinary tract infection after gynecologic surgery. Postoperative asymptomatic bacteriuria often disappears without treatment, but 15-20% of patients still require treatment for postoperative urinary tract infection. This study was carried out to assess the value of prophylactic treatment with methenamine hippurate after routine gynecologic surgery.

This was a prospective, randomized, double-blind, placebo-controlled clinical trial comprising 145 patients undergoing routine gynecologic laparotomy or vaginal plastic surgery using a Foley catheter for 24 h. Antibiotics were not used. Subjects received 1 g Hiprex or placebo twice daily for 5 days. Urine was cultured preoperatively, at catheter removal, and 2 days later. Patients with positive cultures were not given antibiotics unless they were symptomatic. The follow-up period was 1 month.

The chi-square test, Fisher exact test, and t-test were used with level of significance at 0.05, and odds ratios with 95% confidence intervals were calculated.

Asymptomatic bacteriuria was diagnosed in 36 cases (50.0%) in the placebo group and 22 cases (30.1%) in the methenamine group (p = 0.02). Urinary tract infection was diagnosed in 10 cases (13.9%) in the placebo group and two cases (2.7%) in the methenamine group (p = 0.03). There were few adverse events.

Prophylactic treatment with methenamine hippurate significantly reduces the incidence of postoperative bacteriuria and urinary tract infection.