Clinical chorioamnionitis, also called intraamniotic infection (IAI), is a common complication of pregnancy characterized by acute inflammation of the membranes surrounding the developing fetus. Incidence of chorioamnionitis varies based on diagnostic criteria, specific risk factors, and gestational age. Chorioamnionitis is one of the causes of premature labor and delivery.
A bacterial infection is the most likely cause of chorioamnionitis. The infection can start from the vagina, anus or rectum, spreading towards the uterus and pass through the chorioamnion and/or umbilical cord of the placenta. The most common bacteria associated with chorioamnionitis are group B. streptococcus and E. coli.
Chorioamnionitis is associated with the following clinical features:
Certain risk factors are also associated with development of intraamniotic infection, including:
Chorioamnionitis is diagnosed based on clinical findings of fever and other associated signs and symptoms. Laboratory tests, such as CBC and amniotic fluid testing, are requested to detect infection. An ultrasound may also be performed to determine fetal well-being.
Antibiotics have shown a positive outcome in reducing fetal and maternal complications as well as frequency of neonatal sepsis. Currently, research has shown positive outcomes on intravenous administration of ampicillin every 6 hours and gentamicin every 8 to 24 hours until delivery. Early delivery is also recommended and likely to occur to prevent additional issues. Supportive measures include the administration of antipyretics to manage fever.
The main preventative strategy of chorioamnionitis is administration of antibiotics to women with preterm premature rupture of membranes (PPROM). This can reduce the incidence of clinical chorioamnionitis, prolong delivery time and improve neonatal outcomes. Prophylactic antibiotics, such as erythromycin and ampicillin, have been used in clinical trials to determine benefits in prevention and treatment. Amoxicillin/clavulanate antibiotic combinations are contraindicated due to possible risk of necrotizing enterocolitis.
Prevention includes interventions for modifiable risk factors which includes less frequent digital vaginal examinations for ruptured membranes or PPROM and screening for group B streptococcus during the third trimester.
References:
Tita ATN, Andrews WW. (2010). Diagnosis and Management of Clinical Chorioamnionitis. Clin Perinatol. 2010 Jun; 37(2): 339–354. doi: 10.1016/j.clp.2010.02.003
Bany-Mohammed FM. (2018). Chorioamnionitis. Medscape. Taken from: https://emedicine.medscape.com/article/973237-overview
Cleveland Clinic. (2022). Chorioamniotis. Taken from: https://my.clevelandclinic.org/health/diseases/12309-chorioamnionitis
