Post-Cesarean-Section Antibiotics May Prevent SSIs in Obese Women

According to a study consisting of more than 2 million mothers conducted by researchers at Boston University, more than one in five obese mothers are likely to have a cesarean section delivery (c-section), and that number increases to nearly one in every three women at the “high range” of the obesity spectrum (BMI 40+); this is compared to just over 14.1% of mothers having C-sections at “normal” weight.

Not surprisingly, cesarean section deliveries frequently come with additional complications that are not experienced in vaginal deliveries due to the surgical incision associated with the C-section. These complications most commonly include surgical site infections (SSIs), endometriosis, and urinary tract infections (UTIs), according to the American Congress of Obstetricians and Gynecologists (ACOG).

Incidences of these SSIs may be “significantly reduced” by treating obese mothers with a “short course of post-operative prophylactic antibiotics following a C-section delivery,” reported Amy Valent, MD, Oregon Health and Science University (OHSU), at the Annual Meeting of the Society for Maternal-Fetal Medicine (SMFM) in Las Vegas, Nevada. Dr. Valent and her colleagues' recently published research suggests that the use of preventative antibiotics reduces incidences of SSIs, defined as “incisional, organ, or space infections within 30 days of delivery,” in obese women after undergoing a C-section. In addition, they found that the practice is also “cost-effective for the prevention of SSIs in obese women post-cesarean deliveries.”

The group first developed a model specifically “to compare prophylactic, postpartum antibiotics over standard care after cesarean deliveries in obese women,” they wrote, adding that they “stratified” the women based on whether their amniotic membranes were ruptured or intact at time of delivery. “Women were excluded if they had chorioamnionitis, immunosuppression, or planned administration of postpartum antibiotics.” The study included 405 obese women who had C-sections between September 2010 and December 2015. The authors defined “obese” as a pre-pregnancy BMI of ≥30 kg/m2. The patients were randomized and were treated with a combination of cephalexin and metronidazole or a placebo for 48 hours after their delivery. Two hundred and three women received the antibiotics and 202 received the placebo.

Twenty-two women were lost to the study due to lack of follow-up, but of the 383 women who remained, the researchers were able to determine that the prophylactic antibiotic reduced the risk of SSI across women both with and without ruptured amniotic membranes by 60%. The majority of improvement was seen in women with amniotic membrane tears. “The number needed to treat [with antibiotics] to prevent one SSI was 10 for all obese women undergoing cesarean delivery and four for those with ruptured amniotic membranes prior to delivery,” the team noted.

Dr. Valent and her team recently published another study on the topic of prophylactic antibiotic treatments for obese women following a C-section, wherein the group reviewed the cost-effectiveness of this mode of treatment. They determined that “in a population of approximately 459,000 obese women who undergo cesarean delivery within the United States annually, prophylactic post-operative antibiotics would result in 45,900 fewer SSI.” These antibiotics would also result in 9,180 fewer women “suffering from long-term morbidities and five less maternal deaths.” The team estimated an “annual societal savings of $1 billion” before even factoring in quality-adjusted life years (QALYs). “Strong consideration to the adoption of prophylactic post-cesarean antibiotics should be given,” the authors concluded.

According to ACOG, there are a number of weight-associated health risks that come along with obesity and pregnancy, not the least of which is the “increased risk of cesarean delivery.” Due to potential airway obstruction and other complications directly tied to weight, both regional and general anesthesia are riskier for this population even before SSIs come into play. In fact, ACOG’s “Management for Obesity in Pregnancy” notes that the anesthesia involved in a C-section can come with “increased incidence of sleep apnea post-partum” for this population. ACOG already recommends preoperative antibiotics for any obese mother undergoing a C-section, elective or otherwise.