De Vivo V, Carbone L, Saccone G, et al. Early amniotomy after cervical ripening for induction of labor: a systematic review and meta-analysis of randomized controlled trials. Am J Obstet Gynecol. 2019. doi: 10.1016/j.ajog.2019.07.049.
Induction of labor has doubled over the past 2 decades, with almost 25% of parturients currently undergoing induction in the United States.1 Labor induction at term is associated with perinatal outcomes similar to those with spontaneous labor, without an increase in the CD rate.1-3 Although numerous methods for cervical ripening have been evaluated, the safest and most effective method has yet to be determined.2
Amniotomy—or artificial rupture of membranes (AROM)—has long been used as a technique for labor induction and for augmentation in women in spontaneous labor. Purported benefits include an increased responsiveness to exogenous oxytocin, decreased interval to delivery, and an increased likelihood of spontaneous vaginal delivery. Risks of amniotomy include injury to the fetus or surrounding tissues, bleeding, nonreassuring fetal testing, cord prolapse, and prolonged rupture of membranes (defined as longer than 18 hours), which is a risk factor for intra-amniotic infection.
The optimal timing of amniotomy is not known. The recent study by De Vivo and colleagues was designed to better understand the risk/benefit ratio of early amniotomy after cervical ripening in women undergoing induction of labor.
Details of the study
The authors conducted a systematic review and meta-analysis that included 1,273 women in 4 randomized controlled trials to determine the effectiveness of routine early amniotomy versus late amniotomy/spontaneous rupture of membranes after cervical ripening (with either a Foley catheter or prostaglandins) in women with a singleton vertex fetus undergoing induction of labor in the term or late preterm period.
Early amniotomy was defined as AROM “soon after cervical ripening” (cases); late amniotomy was defined as AROM after the active phase of labor or spontaneous rupture of membranes (controls).
The primary outcome was the incidence of CD. Secondary outcomes included the overall length of labor, latency from induction to delivery, and neonatal morbidity (a composite of birth weight, Apgar scores, meconium-stained amniotic fluid, neonatal sepsis, need for resuscitation, and admission to the neonatal intensive care unit).
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