Comparing Vaginal and Oral Administration of Misoprostol for Cervical Ripening and Induction of Labour in Prolonged Pregnancies

Abstract

Background: Dinoprostone (prostaglandin E2), is presently used as the approved standard protocol for cervical ripening and labour induction. In search for a cheaper alternative, misoprostol (prostaglandin E1) has been found to be a good substitute. The ideal dose, route and frequency of administration of misoprostol are, however, still under investigation. Although, vaginal application of misoprostol has been validated as a reasonable means of induction, there is patient resistance to digital vaginal examination and there is a risk of ascending infection. For these reasons, oral administration of misoprostol for cervical ripening and labour induction has been tried.
Objective: The efficacy and safety of oral and vaginal misoprostol for the elective induction of labour with prolonged pregnancy and unfavourable cervix was compared through a prospective study over a period of one year at the Military Hospital, Accra. 
Methods: A prospective, non-blinded randomised study of 148 women with prolonged pregnancy. Data was collected using a prepared structured case record form (data profoma). The study population was randomized into two groups and given 50 μg misoprostol orally in one group and 50 μg vaginally in the other. The main outcomes were measured as induction to delivery time,
vaginal delivery achieved within 24 hours and the incidence of uterine hyperstimulation with fetal heart rate (FHR) changes.
 Results: The mean induction to delivery interval was shorter in vaginal group than oral group but the differences did not reach statistical significance (12.9hrs vs 14.3hrs; mean difference -1.42, P value = 0.24). The shorter duration of vaginal misoprostol, however, was significant for nulliparous women (13.4hrs vs 17.9hrs; mean difference 4.53, p<0.05). There was less failure to achieve vaginal delivery within 24 hours of induction in the vaginal route group, but the differences did not reach statistical significance (6.1% vs. 6.8%; p = 0.81). Fewer women needed oxytocin augmentation in the vaginal group (24.2% vs.17.4%, p = 0.11). There was a higher incidence of uterine hyperstimulation in the vaginal group but not significant (14.7% vs 6.1%, p = 0.10). APGAR scores at 5 minutes showed no difference between the two groups (1.49% vs. 2.99%, p =0.42).
Conclusions: Compared with oral misoprostol, vaginal misoprostol for induction of labour at term resulted in a shorter induction-to-delivery time and a lesser need of oxytocin for women to deliver within 24 hours of induction. Both maternal and neonatal safety outcome were comparable in both groups. However, the more frequent occurrence of hyperstimulation in the vaginal group could lessen its preference to the oral route. More trials are needed to determine the right oral dosage that combines efficacy with safety.