Accurate data on costs attributable to hospital-acquired infections are needed to determine their economic impact and the cost-benefit of potential preventive strategies.

To determine the attributable costs of surgical site infection (SSI) and endometritis (EMM) after cesarean section by means of 2 different methods.

Retrospective cohort.

Barnes-Jewish Hospital, a 1,250-bed academic tertiary care hospital.

There were 1,605 women who underwent low transverse cesarean section from July 1999 through June 2001.

Attributable costs of SSI and EMM were determined by generalized least squares (GLS) and propensity score matched-pairs by means of administrative claims data to define underlying comorbidities and procedures. For the matched-pairs analyses, uninfected control patients were matched to patients with SSI or with EMM on the basis of their propensity to develop infection, and the median difference in costs was calculated.

The attributable total hospital cost of SSI calculated by GLS was $3,529 and by propensity score matched-pairs was $2,852. The attributable total hospital cost of EMM calculated by GLS was $3,956 and by propensity score matched-pairs was $3,842. The majority of excess costs were associated with room and board and pharmacy costs.

The costs of SSI and EMM were lower than SSI costs reported after more extensive operations. The attributable costs of EMM calculated by the 2 methods were very similar, whereas the costs of SSI calculated by propensity score matched-pairs were lower than the costs calculated by GLS. The difference in costs determined by the 2 methods needs to be considered by investigators who are performing cost analyses of hospital-acquired infections.

To determine independent risk factors for endometritis after low transverse cesarean delivery.

We performed a retrospective case-control study during the period from July 1999 through June 2001 in a large tertiary care academic hospital. Endometritis was defined as fever beginning more than 24 hours or continuing for at least 24 hours after delivery plus fundal tenderness in the absence of other causes for fever. Independent risk factors for endometritis were determined by means of multivariable logistic regression. A fractional polynomial method was used to examine risk of endometritis associated with the continuous variable, duration of rupture of membranes.

Endometritis was identified in 124 (7.7%) of 1,605 women within 30 days after low transverse cesarean delivery. Independent risk factors for endometritis included younger age (odds ratio [OR], 0.93 [95% confidence interval {CI}, 0.90-0.97]) and anemia or perioperative blood transfusion (OR, 2.18 [CI, 1.30-3.68] ). Risk of endometritis was marginally associated with a proxy for low socioeconomic status, lack of private health insurance (OR, 1.72 [CI, 0.99-3.00]); with amniotomy (OR, 1.69 [CI, 0.97-2.95]); and with longer duration of rupture of membranes.

Risk of endometritis was independently associated with younger age and anemia and was marginally associated with lack of private health insurance and amniotomy. The odds of endometritis increased approximately 1.7-fold within 1 hour after rupture of membranes, but increased duration of rupture was only marginally associated with increased risk. Knowledge of these risk factors can guide selective use of prophylactic antibiotics during labor and heighten awareness of the risk in subgroups at highest risk of infection.

Independent risk factors for surgical site infection (SSI) after cesarean section have not been well documented, despite the large number of cesarean sections performed and the relatively common occurrence of SSI.

To determine independent risk factors for SSI after low transverse cesarean section.

Retrospective case-control study.

Barnes-Jewish Hospital, a 1,250-bed tertiary care hospital.

A total of 1,605 women who underwent low transverse cesarean section during the period from July 1999 to June 2001.

Using the International Classification of Diseases, Ninth Revision, Clinical Modification diagnosis codes for SSI or wound complication and/or data on antibiotic use during the surgical hospitalization or at readmission to the hospital or emergency department, we identified potential cases of SSI in a cohort of patients who underwent a low transverse cesarean section. Cases of SSI were verified by chart review using the definitions from the Centers for Disease Control and Prevention's National Nosocomial Infections Surveillance System. Control patients without SSI or endomyometritis were randomly selected from the population of patients who underwent cesarean section. Independent risk factors for SSI were determined by logistic regression.

SSIs were identified in 81 (5.0%) of 1,605 women who underwent low transverse cesarean section. Independent risk factors for SSI included development of subcutaneous hematoma after the procedure (adjusted odds ratio [aOR], 11.6 [95% confidence interval {CI}, 4.1–33.2]), operation performed by the university teaching service (aOR, 2.7 [95% CI, 1.4–5.2]), and a higher body mass index at admission (aOR, 1.1 [95% CI, 1.0–1.1]). Cephalosporin therapy before or after the operation was associated with a significantly lower risk of SSI (aOR, 0.2 [95% CI, 0.1–0.5]). Use of staples for skin closure was associated with a marginally increased risk of SSI.

These independent risk factors should be incorporated into approaches for the prevention and surveillance of SSI after surgery.