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Original Investigation
September 19, 2017

Effect of Post–Cesarean Delivery Oral Cephalexin and Metronidazole on Surgical Site Infection Among Obese WomenA Randomized Clinical Trial

Author Affiliations
  • 1Department of Obstetrics and Gynecology, Oregon Health & Science University, Portland
  • 2Department of Obstetrics and Gynecology, University of Cincinnati, Cincinnati, Ohio
  • 3Office of Clinical Research, Investigational Pharmacy, University of Cincinnati Health, Cincinnati, Ohio
  • 4Department of Obstetrics and Gynecology, University of Texas Health Science Center, San Antonio
  • 5Miami Ob/Gyn LLC, Miami, Florida
JAMA. 2017;318(11):1026-1034. doi:10.1001/jama.2017.10567
Key Points

Question  Does postpartum prophylactic oral cephalexin and metronidazole decrease surgical site infection rates among obese women who receive standard preoperative antimicrobial prophylaxis and undergo cesarean delivery?

Findings  In this randomized clinical trial among 403 obese women, the rate of surgical site infection within 30 days following cesarean delivery was 6% with oral cephalexin and metronidazole and 15% with placebo, a significant difference.

Meaning  Among obese women who undergo cesarean delivery, use of prophylactic oral cephalexin and metronidazole may be warranted for prevention of surgical site infection.


Importance  The rate of obesity among US women has been increasing, and obesity is associated with increased risk of surgical site infection (SSI) following cesarean delivery. The optimal perioperative antibiotic prophylactic regimen in this high-risk population undergoing cesarean delivery is unknown.

Objective  To determine rates of SSI among obese women who receive prophylactic oral cephalexin and metronidazole vs placebo for 48 hours following cesarean delivery.

Design, Setting, and Participants  Randomized, double-blind clinical trial comparing oral cephalexin and metronidazole vs placebo for 48 hours following cesarean delivery for the prevention of SSI in obese women (prepregnancy BMI ≥30) who had received standard intravenous preoperative cephalosporin prophylaxis. Randomization was stratified by intact vs rupture of membranes prior to delivery. The study was conducted at the University of Cincinnati Medical Center, Cincinnati, Ohio, an academic and urban setting, between October 2010 and December 2015, with final follow-up through February 2016.

Interventions  Participants were randomly assigned to receive oral cephalexin, 500 mg, and metronidazole, 500 mg (n = 202 participants), vs identical-appearing placebo (n = 201 participants) every 8 hours for a total of 48 hours following cesarean delivery.

Main Outcomes and Measures  The primary outcome was SSI, defined as any superficial incisional, deep incisional, or organ/space infections within 30 days after cesarean delivery.

Results  Among 403 randomized participants who were included (mean age, 28 [SD, 6] years; mean BMI, 39.7 [SD, 7.8]), 382 (94.6%) completed the trial. The overall rate of SSI was 10.9% (95% CI, 7.9%-14.0%). Surgical site infection was diagnosed in 13 women (6.4%) in the cephalexin-metronidazole group vs 31 women (15.4%) in the placebo group (difference, 9.0% [95% CI, 2.9%-15.0%]; relative risk, 0.41 [95% CI, 0.22-0.77]; P = .01). There were no serious adverse events, including allergic reaction, reported in either the antibiotic group or the placebo group.

Conclusions and Relevance  Among obese women undergoing cesarean delivery who received the standard preoperative cephalosporin prophylaxis, a postoperative 48-hour course of oral cephalexin and metronidazole, compared with placebo, reduced the rate of SSI within 30 days after delivery. For prevention of SSI among obese women after cesarean delivery, prophylactic oral cephalexin and metronidazole may be warranted.

Trial Registration  clinicaltrials.gov Identifier: NCT01194115