Active-phase arrest in labor: predictors of cesarean delivery in a nulliparous population.

Abstract

To identify clinical variables associated with cesarean delivery for active-phase arrest with hypotonic labor. We reviewed all deliveries at our institution from September 1975 through March 1989. Data were collected from medical records and a computerized data base. Nulliparas with active-phase arrest were identified and those with hypotonic labor (defined as less than 180 Montevideo units) were selected. The clinical characteristics of each parturient were examined. A linear logistic regression analysis was used to examine the incidence of cesarean delivery as a function of clinical variables. The incidence of active-phase arrest was 4.9%, and hypotonic forces were diagnosed in 81% of the cases managed with an intrauterine pressure catheter. Despite the consistent use of oxytocin in hypotonic labor, the cesarean rate was 60%. Four factors correlated with cesarean delivery in this setting: estimated fetal weight, station at the time of arrest, duration of ruptured membranes, and year of delivery. After an active-phase arrest, cesarean delivery increased when there was suspected cephalopelvic disproportion. In addition, we observed a strong correlation between cesarean delivery and the year of delivery, which suggests a change in physician behavior over time, independent of all other risk factors for cesarean.