Sublingual misoprostol before first trimester abortion: a comparative study using two dose regimens

Various methods have been described for preoperative cervical priming prior to vacuum aspiration (VA) in first trimester pregnancy termination, to facilitate cervical dilatation and shorten the abortion procedure. Recently misoprostol a prostaglandin E1 analogue has been shown to be effective in facilitating cervical dilatation prior to VA. Misoprostol offers several advantages over the other prostagland in analogues including stability at room temperature, ease of administration and minimal side effects.

To determine the optimal dosage and dosing interval for the use of misoprostol administered sublingually for pre-abortion cervical dilatation.

This was a prospective randomised study conducted at Comprehensive Rural Health Project, Ballabgarh the rural health centre under Centre for Community Medicine, AIIMS, New Delhi.

One hundred and twenty pregnant women between 6-11 weeks of gestation opting for voluntary medical termination of pregnancy were (MTP) randomly allocated to either 200 microg or the 400 microg misoprostol group. Vacuum aspiration was performed either two or three hours after administration of sublingual misoprostol. Using Hegar's dilators, degree of cervical dilatation before vacuum aspiration was measured. Other parameters assessed included the amount of additional dilatation required, intra-operative blood loss and associated side effects.

Statistical analysis was conducted using chisquare, the student's t and the Mann-Whitney U tests to examine the difference between the two groups.

In the 200 microg misoprostol group 33% achieved a dilatation of > or = 8 mm compared with 71% of women in the 400 microg misoprostol group. The odds ratio was 95.8 (95% CI 10.2-842.9) for 400 microg misoprostol for successful preoperative cervical dilatation of > or = 8 mm. The mean baseline cervical dilatation for 400 microg and 200 microg misoprostol was 8.2 mm and 6.0 mm respectively (P < 0.001). The use of 400 mg misoprostol with an evacuation interval of two hours appears to be the optimal dosage and evacuation interval. Increasing the time interval beyond two hours did not confer any additional advantage on the rate of successful cervical dilatation but was instead associated with an increased incidence of side effects such as preoperative vaginal bleeding, abdominal pain and shivering.

Our study has shown that Sublingual administration of 400 microg of misoprostol at least two hours before procedure is effective for preoperative cervical dilatation before vacuum aspiration in first trimester pregnancy termination. There is no additional advantages of increasing the dosing interval upto three hours.