Post-discharge surveillance and infection rates in obstetric patients.

OBJECTIVE: To study the impact of post-discharge surveillance on the detection of nosocomial surgical site infection (SSI) after cesarean section and vaginal delivery.

METHODS: During a 21-month period, all patients attending the obstetrics service in labor were recruited for a observational study on the incidence of SSI. Examinations to detect SSI were performed daily during the hospitalization period and up to 30 days after hospital discharge in an outpatient clinic supervised by the Infection Control Committee. The stratification of risk-factors and the criteria for the diagnosis of SSI were done in accordance with the methods described by the Centers for Disease Control and Prevention. The rates of surgical site infection detected during the hospitalization period were compared with those reported by the Centers for Disease Control and Prevention's National (United States) Nosocomial Infection Surveillance System (CDCNNIS) 'benchmarks'. The incidence of SSI detected by post-discharge outpatient surveillance was compared with that from in-hospital surveillance, for both cesarean section and vaginal delivery.

RESULTS: A total of 4463 deliveries were performed during the study period, 2431 (54.5%) by the vaginal route and 2032 (45.5%) by cesarean section. In-hospital surveillance was done on all patients. Post-discharge examinations were done on 951 (46.8%) of the 2032 cesarean section patients. The incidence of SSI in cesarean section detected by in-hospital surveillance was 1.6% (32 cases) and lower than the 3.6% mean rate reported by the CDCNNIS. When SSIs detected by post-discharge surveillance were included, the total number of SSI was 196 cases (9.6%), a value much higher than that for the SSI detected by in-hospital surveillance alone. Only 5 cases (0.21%) of SSI were detected among the 2431 vaginal deliveries.

CONCLUSIONS: The results of our study demonstrate that most of SSI following cesarean section were detected only after patient's discharge from the hospital and seems to indicate that failing to do follow-up evaluation of these patients could result in a substantial mis-calculation of the authentic SSIs rates. Therefore data on post-discharge surveillance should be included to realistically estimate the true rates of SSI in obstetric patients and to allow the implementation of measures to reduce post-partum infection.