Effect of mifepristone on dilatation of the pregnant and non-pregnant cervix

Lancet. 1990 May 26;335(8700):1238-40. doi: 10.1016/0140-6736(90)91303-r.


The effect of the progesterone antagonist mifepristone on the cervix was investigated in two randomised double-blind placebo-controlled trials, the first in 30 women undergoing first trimester surgical termination of pregnancy and the second in 30 non-pregnant premenopausal women. 600 mg mifepristone, given orally 48 h before surgery, increased the mean preoperative cervical dilatation in both pregnant and non-pregnant treatment groups and also reduced the force required to dilate the pregnant and non-pregnant cervix.

PIP: Mifepristone (RU-486) has theoretical potential as a softening agent on the pregnant and nonpregnant cervix. Its potential uses include dilatation and softening of the pregnant cervix before abortion and, outside of pregnancy, reducing the discomfort involved in IUD insertion, endometrial sampling, and hysteroscopy. To further investigate the effectiveness of RU-486, 30 women requesting 1st-trimester pregnancy termination were matched with 30 nonpregnant women scheduled to undergo either cervical dilation and diagnostic curettage or laparoscopic sterilization. Women in both groups were randomly allocated to receive either 600 mg of oral RU-486 or a placebo. The force required to dilate both pregnant and nonpregnant cervixes up to 8 mm was significantly lower (p 0.001) in the mifepristone recipients. Only 27% of the RU- 486-treated pregnant women required any surgical dilatation for their abortion compared to 80% of abortion patients who received a placebo. In addition, mean blood loss during abortion was lower in RU-486-tested subjects than in placebo control; among the nonpregnant dilatation and curettage patients, however, there was no difference in blood loss. No adverse effects were recorded among women who received RU-486 in the 2 hour observation period after drug administration. In terms of its mechanism of action, it is possible that mifepristone increases the active estrogen-progesterone ratio at the receptor level. Despite clarity about this process, more widespread use of RU-486 is recommended in both pregnant and nonpregnant women to reduce the risk of cervical trauma.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Administration, Oral
  • Adolescent
  • Adult
  • Cervix Uteri / drug effects*
  • Cervix Uteri / physiology
  • Double-Blind Method
  • Drug Evaluation
  • Female
  • Humans
  • Middle Aged
  • Mifepristone / administration & dosage
  • Mifepristone / pharmacology*
  • Pregnancy
  • Randomized Controlled Trials as Topic


  • Mifepristone