Objective: To compare the effectiveness of vaginal misoprostol administered 6 or 12 hourly for second trimester pregnancy termination.
Design: A randomised controlled trial.
Setting: University teaching hospital.
Sample: Two hundred and seventy-nine pregnant women at gestations between 14 and 26 weeks undergoing pregnancy termination.
Methods: Women were randomised to receive 600-microg misoprostol tablets vaginally either every 6 hours or every 12 hours until abortion occurred.
Main outcome measures: Induction-abortion interval, success rate within 24 and 48 hours and adverse effects.
Results: There was no significant difference in the median induction to abortion interval 6 hours (16 hours) and 12 hours (16 hours; P= 0.80). The total dose of misoprostol was higher in the 6-hour group (1800 vs 1200 microg). The cumulative abortion rates within 24 hours were 74% and 67% and within 48 hours 94% and 92%, in the 6- and 12-hour groups, respectively. Fever was more common in the 6-hour group (53%) versus the 12-hour group (31%; P < 0.001). The incidence of nausea, vomiting, diarrhoea, severe bleeding and abdominal pain were similar.
Conclusions: Misoprostol (600 microg) administered at 12-hour intervals was associated with fewer adverse effects and was as effective as a 6-hour interval.