Chorioamnionitis and intraamniotic infection

Abstract

Intraamniotic infection is a common (2-4%) event in labor. The predictors of IAI include preterm labor or rupture of membranes, abnormal vaginal flora (e.g., GBS, sexually transmitted disease, bacterial vaginosis), obstetric manipulations (e.g., vaginal exams, internal fetal monitoring) in the presence of ruptured membranes, and diminished host response (due to smoking, drug abuse, obesity, immunodeficiency states, etc.). Group B Streptococcus and Enterobacteriaceae are the most important organisms associated with the polymicrobial infection. Anaerobes predict post-cesarean section complications. Neonatal pneumonia (2-5%) and early neonatal sepsis (1-4%) are the outcomes of the greatest concern and are caused by group B streptococcal or aerobic gram-negative rod infections. These outcomes are kept to a minimum if maternal antibiotic chemotherapy is started interpartum with agents that are safe, cross the placenta, and are active against GBS and Escherichia coli (e.g., ampicillin plus gentamicin). Anaerobic coverage should be added (clindamycin) if a cesarean section is performed. Antipyretics such as acetaminophen will reduce the hyperthermic stress on the fetus, and persistent fetal tachycardia after antipyretics may indicate fetal infection. Continuous electronic fetal monitoring is appropriate in cases of IAI, and providers should be prepared for neonatal resuscitation, early neonatal intravenous antibiotics, and respiratory support at delivery.