Surgical Site Infection Prophylaxis in Obese Women Undergoing Cesarean Delivery

Kayla Peltier, Mercer University College of Pharmacy

The Centers for Disease Control and Prevention (CDC) has reported that in 2015 cesarean deliveries accounted for 32.0% of all reported births. [1] One of the complications of cesarean deliveries is post-cesarean surgical site infection (SSI), and the reported incidence has ranged from 3.7% to 9.8% worldwide. [2] There several risk factors for developing post-cesarean SSI, and obesity is one of the reported factors. [2] This may raise a concern in the United States as the CDC also has reported 38.3% of women who are 20 years of age and older are obese. [3]

While obesity has been identified as an independent risk factor for the development of post-cesarean delivery SSI, limited data is available to attempt to determine the optimal antimicrobial regimen for prophylaxis in obese patients. [4] One gram of cefazolin has been identified as sufficient antimicrobial prophylaxis for post-cesarean SSIs in the general population; however, there are concerns of its efficacy in obese women. [2] Therefore, this study aimed to determine the efficacy of oral cephalexin and oral metronidazole as antimicrobial prophylaxis for post-cesarean SSI in obese women. [4]

Effect of Post-Cesarean Delivery Oral Cephalexin and Metronidazole on Surgical Site Infection Among Obese Women: A Randomized Clinical Trial
Design Randomized, double-blind clinical trial; N= 403
Objective To determine rates of SSI among obese women who receive antimicrobial prophylaxis with oral cephalexin and metronidazole vs. placebo for 48 hours following cesarean delivery
Study Groups Oral cephalexin and metronidazole (C-M; n= 202)

Placebo (n= 201)

Methods Inclusion Criteria:

–       Pre-pregnancy BMI >30

–       Final plan for cesarean delivery

–       >13 years old

Exclusion Criteria:

–       Known immunodeficiency syndromes

–       Planned administration of antibiotics during the postpartum period for any medical or obstetric indication

All subjects received chlorhexidine skin preparation and cefazolin 2 g IV prior to incision. Cesarean deliveries were performed by standard accepted practice, and fascia was closed with a monofilament suture in a running-stitch fashion. Subjects were randomized to receive either both oral cephalexin 500 mg and oral metronidazole 500 mg every 8 hours for a total of six doses, or placebo.

Duration October 2010-December 2015, final follow-up through February 2016
Primary Outcome Measure SSI within 30 days after cesarean delivery
Baseline Characteristics  

  C-M (n= 202) Placebo (n= 201)
Maternal age, mean (SD), y 28.5 (5.6) 28.1 (5.6)
Maternal race/ethnicity
  Non-Hispanic black 112 (55.4) 92 (45.8)
  Non-Hispanic white 79 (39.1) 104 (51.7)
  Hispanic/Latino 6 (3.0) 3 (1.5)
  Other 5 (2.5) 2 (1.0)
Body mass index, mean (SD)
  30-39.9 117 (58.2) 117 (57.9)
  40-49.9 65 (32.2) 66 (32.8)
  >50 20 (9.9) 18 (9.0)
Primary cesarean deliverya 83 (40.9) 81 (40.3)
Perinatal and intrapartum factors
  Gestational age at delivery, mean (SD),


37.3 (2.9) 36.9 (4.0)
  Gestational diabetes 41 (20.2) 29 (14.4)
  Preeclampsia 43 (21.3) 45 (22.4)
  Group B streptococcus colonized 65 (32.2 68 (33.8)
  Labor prior to delivery 70 (34.2) 76 (37.5)
  Rupture of membranes 64 (31.5) 63 (31.3)
Surgical Factors
  Scheduled cesarean delivery 128 (66) 118 (62)
  Duration of surgery, mean (SD), min 71.0 (22.1) 71.9 (1.7)
  Suture skin closure 189 (93.1) 194 (96.5)
a Primary cesarean delivery is first-time cesarean delivery in a pregnant woman.

Select information provided.


  No. (%) [95% CI] With Outcome

(n= 202)

Placebo (n= 201) Mean Between-Group Difference, % (95% CI) Relative Risk (95% CI) p value
Primary outcome 13 (6.4) [3.0-9.8] 31 (15.4) [10.4-20.4] 9.0 (2.9-15.0) 0.41 (0.22-0.77) 0.01
Adverse Events Common Adverse Events: Nausea (incidence not disclosed)
Serious Adverse Events: None reported
Percentage that Discontinued due to Adverse Events: 3% (12/403; 4 (2%) in the antibiotic group, 8 (4%) in the placebo group)
Study Author Conclusions Antimicrobial prophylaxis with oral cephalexin and oral metronidazole for 48 hours after cesarean delivery provides a significant reduction in surgical site infections in obese women.

This evidence suggests that prophylaxis with preoperative cefazolin and postoperative oral cephalexin and oral metronidazole significantly reduced the rate of surgical site infections in obese women after cesarean delivery.


[1] Martin JA, Hamilton BE, Osterman MJK, Driscoll AK, Matthews TJ. Births: final data for 2015. Natl Vital Stat Rep. 2017;66(1):1-70.

[2] Fitzwater JL, Tita AT. Prevention and management of cesarean wound infection. Obstet Gynecol Clin North Am. 2014;41(4):671-89.

[3] Ogden CL, Carroll MD, Fryar CD, Flegal KM. Prevalence of obesity among adults and youth: United States, 2011-2014. NCHS Data Brief. 2015;(219):1-8.

[4] Valent AM, DeArmond C, Houston JM, et al. Effect of Post-Cesarean Delivery Oral Cephalexin and Metronidazole on Surgical Site Infection Among Obese Women: A Randomized Clinical Trial. JAMA. 2017;318(11):1026-1034.


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