Approximately 8 percent of pregnant women at term present with premature rupture of membranes (PROM) but no active labor. If PROM persists, the risks of infectious complications are greatly increased. Research indicates that induction of labor reduces the risk of infection and other complications of PROM at term. Butt and colleagues compared the efficacy of two strategies to induce labor: oral misoprostol and intravenous oxytocin.
The study included women with confirmed PROM at 37 or more weeks of gestation who were not in active labor on presentation. All of the mothers were white and had singleton pregnancies in cephalic presentation. Exclusions included any contraindication to vaginal delivery, active bleeding, signs of infection, history of uterine surgery and fetal abnormality. After stratification for parity, the 108 women were randomly assigned to induction of labor using misoprostol (50 μg every four hours) or intravenous oxytocin (2 mIU per minute and increasing by 2 mIU per minute every 15 to 30 minutes at the discretion of the attending physician). All patients were continuously monitored for fetal heart rate and uterine contractions. Decisions about analgesia, epidural use, frequency of vaginal examinations and conduct of the delivery were at the discretion of the attending physician. The primary outcome studied was time to vaginal delivery. Additional outcomes included neonatal Apgar score and general status, rates of infection, cesarean delivery, perineal trauma, epidural use and patient satisfaction.
The two groups of patients were comparable in all important respects. No differences were found in the type of delivery (cesarean, forceps, vacuum or spontaneous) between the two treatment groups. Women receiving oral misoprostol had a mean time to vaginal delivery of 720 ± 382 minutes compared with 501 ± 389 minutes in women receiving oxytocin. This significant difference was accounted for by differences in the time to achieve full dilation of the cervix. No significant differences were measured between the treatment groups in any of the secondary outcomes. Fifty-six percent of the women initially treated with misoprostol required augmentation of labor with oxytocin.
The authors conclude that treatment with oral misoprostol and intravenous oxytocin were both effective, but that oxytocin treatment resulted in a shorter induction-to-delivery time.