Objective: To test the safety and efficacy of prostaglandin E(2) (PgE(2)) as a treatment for dystocia in spontaneous labour.
Design: Randomised, double-blind, placebo-controlled trial.
Setting: Multicentre study in nine university-affiliated hospitals in Canada. Population Three hundred and thiry-two nulliparous women with spontaneous labour at term.
Methods: Women who had progressed < 2 cm of cervical dilation in the 4 hours following the diagnosis of labour were randomly assigned to receive a single dose of either 1 mg (n= 112) or 2 mg (n= 111) PgE(2) vaginal gel or placebo gel (n= 109).
Main outcome measures: The primary outcome was resolution of dystocia, defined as a change in cervical dilatation of >0.5 cm per hour in the 6 hours following gel administration. Secondary outcomes were progress of labour, uterine hyperstimulation (more than five contractions in 10 minutes or a contraction lasting more than 2 minutes), use of oxytocin, method of delivery, maternal and neonatal morbidity.
Results: Dystocia resolved more often after PgE(2) 1 mg (49%), RR 1.53 (95% CI 1.1, 2.1) and PgE(2) 2 mg (49%), RR 1.5 (CI 1.1, 2.1), compared with placebo (32%). Hyperstimulation was increased after PgE(2) 2 mg treatment (15%), RR 5.6 (95% CI 1.7, 18), but not after PgE(2) 1 mg (5.4%), RR 1.9 (CI 0.50, 7.6) when compared with placebo (2.8%). There was an increase in caesarean sections performed in the second stage of labour in the PgE(2) groups versus placebo. There were no differences in measures of maternal or neonatal morbidity.
Conclusion: A single 1-mg dose of PgE(2) vaginal gel is more effective than placebo in resolving dystocia, without increasing uterine hyperstimulation, but may be associated with an increase in the incidence of second stage caesarean section.