A comparison of oral and vaginal misoprostol tablets in induction of labour at term

Objective To compare the efficacy of equivalent doses of orally administered with vaginally administered misoprostol in induction of labour at term.

Design A non-blinded randomised controlled trial.

Setting Induction and labour wards of a UK; teaching hospital.

Participants Two hundred and forty-five pregnant women at term, with medical or obstetric indications for labour induction and unfavourable cervices.

Methods The women were randomly assigned to receive 50 mu gm of misoprostol orally or vaginally four hourly to a maximum of five doses.

Main outcome measures interval from induction to vaginal delivery, mode of delivery, oxytocic and analgesic requirements in labour, neonatal outcome, patient satisfaction and acceptability.

Results The mean induction to vaginal delivery interval was significantly shorter in the vaginal group compared with the oral group (17.8h vs 27.9h: mean difference 10.1hrs, 95% CI 5.8-14.4). More women were delivered within 24 hours (80% vs 46.3%; RR 1.7, 95% CI 1.3-2.1) and fewer women needed oxytocin augmentation (39% vs 58.2%; RR 0.67, 95% CI 0.5-0.9) in the vaginal group. Then was no difference in the mode of delivery, analgesic requirements or neonatal outcomes in the two groups. There was a higher incidence of uterine hyperstimulation in the vaginal group (4.9% vs 0.8%, RR 6, 95% CI 0.07-48.7) and more caesarean sections were performed for fetal distress in this group(13% Vs 2.4%: RR 5.3, 95% CI 1.6-17.7), although the overall operative delivery rate was similar in the two groups.

Conclusion Misoprostol effectively induces labour. with the vaginal route of administration having a faster action than the oral route in equivalent doses. However, the more frequent occurrence of hyperstimulation and the higher intervention rate for fetal distress in the vaginal group could mean that the preferred route might be oral. More trials are needed to find the right oral dosage that combines efficacy with safety.