Infectious morbidity associated with early amniotomy during labor induction

This study's purpose was to determine if an early amniotomy increased the risk of maternal and neonatal infectious morbidity when compared with late amniotomy.

This was a single-center retrospective cohort study performed between 1/1/2010 and 3/31/2018. It assessed the relationship between eligible term women undergoing labor induction with early amniotomy, defined as artificial rupture of membranes (AROM) performed less than 12 h from start of cervical ripening, compared with women who do not have an early amniotomy. The primary outcome was a composite of chorioamnionitis and/or neonatal sepsis. Secondary outcomes included isolated maternal fever, composite maternal morbidity, cesarean delivery, amnioinfusion, any transfusion, length of labor induction, cord prolapse, NICU admission, and Apgar score.

Among the 1200 patients, the rate of chorioamnionitis or neonatal sepsis was lowest at 0.4 % for patients with early amniotomy <12 h, increased to 3.5 % in both the interval to AROM 12 to <18 h and 18 to <24 h, and further increased to 5.9 % when AROM occurred after 24 h from start of cervical ripening (p = 0). For the secondary outcomes, the rate of cesarean was significantly lower in the early AROM group <12 h at 13.9 % compared to all other later periods of AROM, with the highest rate in the >24 h group (34.9 %, p = 0). The mean time from amniotomy to delivery was increased across each time interval, lowest at 11.5 in the <12-hour interval and highest at 44.6 h for the interval with AROM at 24 h and beyond (p = 0). Composite maternal morbidity also increased across each time interval, lowest in the <12-hour group at 17.6 % and highest in the group that had AROM occur after 24 h at 31.2 % (p = 0). There were no significant differences in neonatal secondary outcomes.

When amniotomy is performed <12 h after initiation of cervical ripening, there does not appear to be an increased rate of infectious morbidity. When performing amniotomy in a closer time interval to end of cervical ripening, it appears infectious morbidity may be reduced with shorter duration from amniotomy to delivery while decreasing cesarean and maternal morbidity rates.