SAN DIEGO – The combination of povidone-iodine with chlorhexidine with alcohol reduced the rate of surgical site infections by 83% in obese women undergoing nonemergency cesarean deliveries, according to the results of a large randomized trial.
But among women with a lower body mass index (BMI < 40 kg/m2), there were no overall differences in surgical site infection (SSI) rates using either povidone-iodine with alcohol, chlorhexidine with alcohol, or a combination of both agents for the preparation of cesarean delivery.
Dr. Ivan Ngai
“Body surface area is greater in this subset of patients, so the volume of prep solution could have played a role,” Dr. Ivan Ngai, one of the researchers, said in an interview. “Also, it’s known that the organism that colonizes skin in obese persons, compared with nonobese persons, is different, especially increased colonization by fungus. We think that’s why the prep combination played a role, because iodine is better against fungi than chlorhexidine.”
In what Dr. Ngai said is among the largest studies of its kind for cesarean deliveries, he and his associates randomized 1,404 women at greater than 37 weeks’ gestational age undergoing a nonemergent cesarean section between January 2013 and July 2014 to receive one of three preparations: povidone-iodine plus alcohol (povidone group); chlorhexidine plus alcohol (chlorhexidine group), or povidone-iodine plus alcohol and chlorhexidine plus alcohol (combination group).
The primary outcome was the rate of SSI within 30 days of the cesarean delivery. The researchers used univariate and multivariable regression models to determine whether specific prep groups and other clinical variables were independent predictors of SSI. They presented their findings at the annual Pregnancy Meeting sponsored by the Society for Maternal-Fetal Medicine.
The mean age of the study participants was 30 years old. Dr. Ngai reported that 457 women in the povidone group completed follow-up, compared with 454 in the chlorhexidine group and 454 patients in the combination group.
There were 60 (4.3%) SSIs, with no differences between skin prep groups in demographics, medical disorders, indications for cesarean, operative time, blood loss, or SSI rates. The SSI rate of 4.3% “was much lower than the 9%-14% usually reported in cesarean birth,” Dr. Ngai said. “We think it’s lower because we did not include cases of emergent cesarean delivery.”
Multivariable analysis revealed that increasing maternal BMI, excessive blood loss (greater than 1,000 mL), and preeclampsia were independent predictors of SSIs. Women in the combination group who had a BMI of 40 kg/m2 or greater had an 83% reduction in SSI (odds ratio, 0.17; P = .02).
While a formal cost analysis was not conducted, each surgical site infection averages about $3,500 extra health care dollars per event, said Dr. Ngai of the department of obstetrics and gynecology and women’s health at Albert Einstein College of Medicine, New York.
In the subgroup of patients with a BMI of 40 kg/m2 or greater, the researchers estimated that they would have to use combination prep on about 12 patients to prevent one SSI infection. This compared with using chlorhexidine prep alone on 21 patients to prevent one SSI infection.
“In a nonobese population, the difference between povidone-iodine or chlorhexidine or combination of the two with alcohol makes no difference in preventing SSI,” Dr. Ngai concluded. “But in the obese population, the combination of povidone-iodine with chlorhexidine with alcohol plays a significant role in reducing the SSI rate.”
The researchers reported having no relevant financial conflicts.
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