Re: Misoprostol and uterine rupture

Dear Sir, I read with interest the recent article by Roberts et al., titled, ‘Misoprostol to induce labour: a review of its use in a NSW hospital’.1 The authors rightly note that misoprostol is an effective and cheap method of labour induction which is used commonly in the USA. They report two cases of uterine rupture among 789 multiparous women induced with misoprostol. Neither case was associated with neonatal morbidity although hysterectomy was required in both cases. They reported no cases of uterine rupture following misoprostol induction in 1209 nulliparas. Prostaglandin analogs are known to increase rupture rates in women with scarred uteri. Therefore, analyses on the use of misoprostol for labour induction usually focus on the multiparous population. Most authorities recommend its careful use in women with prior caesarean delivery. Indeed, the American College of Obstetricians and Gynaecologists recommends that misoprostol be avoided in women with a previous caesarean section.2 We recently reviewed documented cases of spontaneous uterine rupture in primigravid women3 and are aware of at least three reported cases of misoprostol-associated rupture of the primigravid uterus. Two cases occurred in women with no pre-existing risk factors for uterine rupture (following one and two doses of 50 µg, respectively).4,5 The third rupture followed a 200-µg dose of misoprostol in a woman with a known uterine anomaly.6 Roberts et al. are correct in concluding that uterine rupture is a rare complication following misoprostol use and this is undoubtedly the case in primigravid women. However, practitioners must be vigilant that the primigravid uterus is not immune to rupture and that misoprostol should still be used judiciously in first labours.