Body mass index as a major risk factor for c-section-related surgical site infections (CSRSSI) and introduction of a prevention bundle

Background: A tertiary care women’s center averages 400 deliveries per month, of which 39% are by cesarean section.  From Jul 2009 to Jun 2010, 45 CSRSSIs were identified out of 1,943 procedures for a global rate of 2.3%.  We performed a case control analysis to determine risk factors for CSRSSI and used the data to develop, implement, and evaluate strategies to decrease these infections.

Objective: Perform a case control analysis to determine CSRSSI risk factors and develop, implement, and evaluate strategies to decrease CSRSSI.

Methods: A retrospective case control study was conducted using c-section data from Oct-Dec 2009.  All patients with procedures were classified as cases or controls based on the development of a post surgical CSRSSI which were determined based on Centers for Disease Control, National Healthcare Safety Network (NHSN) criteria.

Results: Our case control study included 337 procedures, out of which 14 developed a CSRSSI (4.15%).  Body mass index (BMI) was the strongest predictor of CSRSSI among all NHSN risk categories. Obese and morbidly obese patients had an odds ratio for CSRSSI development of 2.8 and 5.0, respectively. In Aug 2010, a “bundle” was implemented as a three month pilot with the goal of reducing CSRSSIs, and specifically targeting obese patients.  The bundle consisted of a pre-operative Chlorhexidine abdominal scrub, use of wound dressing for a minimum of 24 hours post-op, and increasing the prophylactic dose of cefazolin to 3g for patients weighing greater than 100kg.  Preliminary bundle compliance results from Aug-Sept 2010 were 98% for correct prophylactic dosage, 50% for documented chlorhexidine abdominal scrub, 58% for dressing placement, and 22% for documentation of dressing removal at 24 hours.  Preliminary surveillance from Aug-Sept 2010 identified 316 procedures with 11 CSRSSI (3.5%).

Conclusions: As with other surgical site infections, BMI appears to be a significant risk factor for CSRSSI that is not currently considered in the risk adjustment by NHSN. While it is too early to assess the full impact of our bundle, since compliance is not yet optimal, new and novel approaches to decrease the risk of CSRSSI in obese patients merit further investigation.