Antibiotic prophylaxis before surgery vs after cord clamping in elective cesarean delivery: a double-blind, prospective, randomized, placebo-controlled trial.

CONTEXT Perioperative antibiotic prophylaxis during elective cesarean delivery at term to reduce postoperative maternal infectious morbidity is generally used but may not be effective on the basis of the available data. Also, the optimal timing of prophylactic antibiotic administration is unclear. OBJECTIVE To compare the effectiveness of cefazolin administered before skin incision vs cefazolin administered after umbilical cord clamping vs placebo in a 3-arm randomized trial. The primary objective of the study was to compare postoperative infectious morbidity, defined as wound infection, endometritis, or urinary tract infection (primary end point), in women with cefazolin vs placebo. The comparison between the 2 arms administering cefazolin before skin incision vs after umbilical cord clamping was a secondary end point. DESIGN Double-blind, prospective, randomized, placebo-controlled trial. SETTING The Department of Obstetrics and Gynecology, Medical University of Vienna, Vienna, Austria. PATIENTS We recruited 1112 women undergoing elective cesarean delivery at term from March 1, 2004, through January 31, 2010. INTERVENTIONS In group 1, cefazolin (2 g) was administered 20 to 30 minutes before skin incision. In group 2, cefazolin (2 g) was administered immediately after clamping of the cord. In group 3, placebo was administered before skin incision. RESULTS The primary outcome was observed in 18 of 370 women in group 1 (4.9%) and in 14 of 371 women in group 2 (3.8%), whereas it was noted in 45 of 371 women in group 3 (12.1%) (P < .001 for group 1 plus group 2 vs group 3). The number needed to treat to avoid 1 primary outcome was 13 (95% CI, 9 to 24). Between groups 1 and 2, there was no statistically significant difference regarding postoperative infectious morbidity (P = .60). CONCLUSION We were able to demonstrate the usefulness in elective cesarean delivery of prophylactic cefazolin vs placebo in reducing postoperative maternal infectious morbidity.