Incremental risk of clinical chorioamnionitis associated with cervical examination

Clinical chorioamnionitis is associated with significant maternal and neonatal morbidity, yet there is no clear evidence on the association between cervical examinations and infection.

We sought to assess the association between the number of cervical examinations performed during term labor management and the risk of clinical chorioamnionitis.

This is a retrospective cohort study of term (≥37 weeks of gestation), singleton pregnancies who labored at our tertiary care center from 2014 to 2018. The primary outcome of clinical chorioamnionitis was defined as maternal intrapartum fever (single oral temperature of >39°C or 38°C-38.9°C for 30 minutes) and 1 or more of the following: maternal leukocytosis, purulent cervical drainage, or fetal tachycardia. The primary exposure was the number of digital cervical exams documented in the medical record. Log-binomial regression was used to model the effect of cervical examinations on the risk of clinical chorioamnionitis while adjusting for potential confounders.

A total of 20,029 individuals met the inclusion criteria and 1028 (5%) patients experienced clinical chorioamnionitis. The number of cervical exams was associated with increased risk of developing infection after adjusting for potential confounders. Individuals with ≥8 cervical exams had 1.7 times the risk of developing clinical chorioamnionitis compared with those with 1 to 3 exams. Prolonged rupture time, nulliparity, Black race, Medicaid insurance, higher gestational age, and higher body mass index were associated with increased risk of clinical chorioamnionitis, whereas smoking and group B Streptococcus colonization were associated with a lower risk.

Our study found that the number of cervical exams performed during labor is an independent risk factor for developing clinical chorioamnionitis. Unnecessary cervical exams should be avoided during labor management at term.