Randomized trial to determine optimal dose of vaginal misoprostol for preabortion cervical priming.

Abstract

To determine the optimal dosage of vaginal misoprostol for cervical priming before vacuum aspiration abortion. One hundred twenty women were assigned randomly to receive 200, 400, 600, or 800 microg of misoprostol given vaginally. Vacuum aspiration was performed 3-4 hours after the insertion of misoprostol tablets. The degree of cervical dilation before operation was measured with a Hegar dilator. Preoperative and intraoperative blood loss and associated side effects also were assessed. Twenty-nine (96.7%) women in the 400-microg group and all in the 600-microg and 800-microg groups achieved cervical dilation of at least 8 mm. The success rate for the 200-microg group was only 23.3%, significantly less efficacious than the 400-microg dose (odds ratio 95.3; 95% confidence interval 10.9, 830.9; P < .001). There was no significant difference among the 400-, 600-, and 800-microg groups (P = .364) with respect to achieving cervical dilation at least 8 mm. However, 800 microg was associated with significantly more side effects than 600 microg (preoperative and intraoperative blood loss, P < .001; abdominal pain, P = .005; products of conception at os, P < .001; fever higher than 38.0C, P = .002). When 400 microg and 600 microg were compared, we found that the higher dose also was associated with significantly more side effects. The 600-microg group was used twice in the comparison, but all P values remained significant even after the Bonferroni adjustment for multiple comparisons. Vaginal application of 400 microg of misoprostol is the optimal dose for vacuum aspiration preabortion cervical dilation in first-trimester nulliparas.