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Mifepristone (RU486) and abortion

A safe, effective and acceptable alternative to surgery

MJA 1997; 167: 292-293


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There is overwhelming evidence that the provision of safe and accessible induced abortion is a major factor in preserving the reproductive health of women, but 24% of the world's population live in countries where abortion is not legally permitted. Abortion in these countries can involve spells and incantations, ingestion of herbs or manipulations, such as introducing sticks or disinfectants into the uterine cavity. Such methods vary from being harmless, but ineffectual, to highly lethal, and it is not surprising that 99% of maternal deaths from abortion occur in countries where the more dangerous of these practices are common.1

In Australia, where abortion is widely available and publicly funded, service providers have a duty to ensure that, as with any other legally available medical procedure, the methods used are safe, effective and acceptable.

It has been estimated one in three Australian women will seek an induced abortion during their reproductive lifetime.

Abortion can be achieved either surgically or medically. Surgical procedures include uterine evacuation via the vagina, and vacuum aspiration is now used to perform over 98% of all first-trimester abortions,2 providing the benchmark against which newer techniques must be assessed. In countries where abortion is legal and supervised by a trained practitioner, vacuum aspiration is very safe and effective. Maternal death occurs in only one in 100000 cases, serious morbidity in less than 1% of cases, and minor morbidity (including psychological disturbances) in 10% of cases. Severe haemorrhage, infective complications and genital tract trauma account for 85% of all major complications. Minor morbidity most often includes prolonged uterine bleeding, retained products of conception, or uterovaginal infection.2,3

It has been estimated that at current rates of abortion one in three Australian women will seek an induced abortion during their reproductive lifetime.4 As 70% of all women who undergo abortion intend to have children in the future, even a small increase in the risk of adverse future reproductive outcomes would have a major impact. Well-controlled, prospective cohort studies suggest that there is no increased risk of complications (including miscarriage and preterm delivery) during future pregnancies after a single abortion by vacuum aspiration, but there are fewer data on multiple vacuum aspiration abortions.5

In 1978 the World Health Organization recommended research into the "development of a non-surgical method of abortion, non-toxic to the woman and non-teratogenic in an effective dosage, reliably producing complete expulsion of the products of conception, suitable for application in a non-clinical setting and economically accessible to women in all countries". Methods of medical induction of abortion include prostaglandins used alone (such as misoprostol, which is available on the Australian Schedule of Pharmaceutical Benefits for other indications, and widely used in other countries for inducing abortion) and, more recently, the antiprogesterones.6

Progesterone is vital for the support of the developing embryo, and the antagonism of this hormone has been tested clinically by inhibiting its production and by direct blockade of progesterone receptors. Drugs such as epostane and trilostane act indirectly by inhibiting the conversion of the precursor, pregnenolone, into progesterone. However, these drugs have been overshadowed by the development of mifepristone, which blocks the action of progesterone at the receptor level.

Used alone, mifepristone is not an effective abortifacient, but it becomes one when combined with prostaglandin analogues. Mifepristone (200 mg, orally) used with misoprostol (400 mg, orally or vaginally) results in complete abortion (complete expulsion without the need for subsequent surgical uterine evacuation) at rates of over 95%, with 98% of all women able to leave hospital within eight hours of prostaglandin administration. Efficacy declines as gestational age increases, so this method is usually restricted to gestations of less than nine weeks.

The process of care and frequency of unpleasant side effects associated with any procedure will affect its acceptability and hence uptake by the community as a whole. The main short term sequelae of medical abortion include pelvic pain, vaginal bleeding and gastrointestinal disturbance, but these are short lived, and most women return to normal daily activity after 24 hours.7 Women are not anaesthetised in any way during medical abortion, but around 50% require analgesia, and the products of conception may be visualised.

Despite these apparent drawbacks, the acceptability of medical abortion is high among European and Chinese women.8,9 Australian women, as reported by Mamers and colleagues in this issue of the Journal, also find the process acceptable.10 Women who sought medical abortion in the Australian arm of an international trial sponsored by the World Health Organization were satisfied with the method and most found the associated level of pain acceptable; those who had had previous surgical abortions also found the medical method more acceptable. Reasons given by Australian women for choosing medical abortion included avoidance of anaesthesia and increased autonomy, that medical abortion is more "natural" and emotionally acceptable, and that it is less stressful. Women also seem to have strong preferences for a particular method -- over 90% of the women interviewed in a British trial indicated that they would have been prepared to pay a premium to ensure that they had a choice of abortion method.11

Prospective randomised trials and cohort studies of vacuum aspiration and mifespristone/prostaglandin regimens have compared safety, efficacy, acceptability, psychological outcomes, economic outcomes and long term sequelae of these alternative methods. There seem to be few differences between the alternatives in any of the parameters studied, and indeed medical abortion may be the procedure of choice at very early (less than seven weeks) gestations. In some United Kingdom hospitals, 60% of abortions are now performed medically, and worldwide over one million women have used the regimen.12-14

Mifepristone has other clinical uses. It has been used to shorten the process and reduce analgesia requirements in labour induction in cases of second-trimester and third-trimester abnormal pregnancy or intrauterine fetal death. Medical uterine evacuation in first-trimester miscarriage is also being explored.15

Critics of mifepristone claim that it will make abortion "easier". The meaning of "easier" is often not defined, but could include easier access to safe abortion services, an easier treatment for medical and nursing staff to administer, or easier -- both physically and psychologically -- for the women having abortions. Some claim that this will lead to an overall increase in the frequency of abortion, although there is no evidence to support this assumption. It is clear, however, that mifepristone/prostaglandin regimens offer safe, effective and acceptable alternatives to surgery that will tend to reduce maternal mortality and morbidity in both developed and, more especially, developing nations.

Richard C Henshaw
Obstetrician and Gynaecologist
Queen Elizabeth Hospital, Woodville, SA

  1. Mahler H. The safe motherhood initiative: a call to action. Lancet 1987; 1: 668-670.
  2. Henshaw RC, Templeton AA. Methods used in first trimester abortion. Curr Obstet Gynaecol 1993; 3: 11-16.
  3. Grimes DA, Cates W. Complications from legally induced abortion: a review. Obstet Gynaecol Surv 1979; 34: 177-191.
  4. An information paper on termination of pregnancy in Australia. Canberra: National Health and Medical Research Council, 1997.
  5. Hogue CJR, Cates W, Tietze C. The effects of induced abortion on subsequent reproduction. Epidemiol Rev 1982; 4: 66-94.
  6. Misoprostol and legal medical abortion [editorial]. Lancet 1991; 338: 1241-1242.
  7. Henshaw RC, Naji SA, Russell IT, Templeton AA. A comparison of medical abortion (using mifepristone and gemeprost) with surgical vacuum aspiration: efficacy and early medical sequelae. Hum Reprod 1994; 9: 2167-2172.
  8. Bachelot A, Cludy L, Spira A. Conditions for choosing between drug induced and surgical abortions. Contraception 1992; 45: 547-549.
  9. Tang GW, Lau OW. Further acceptability evaluation of RU486 and ONO 802 as abortifacient agents in a Chinese population. Contraception 1993; 48: 267-276.
  10. Mamers PM, Lavelle AL, Evans AJ, et al. Women's satisfaction with medical abortion with RU486. Med J Aust 1997; 167: 316-317.
  11. Howie FL, Henshaw RC, Naji SA, Russell IT, Templeton AA. Medical abortion or vacuum aspiration? Two year follow up of a patient preference trial. Br J Obstet Gynaecol 1997; 104: 829-833.
  12. Kaunitz AM, Rovira EZ, Grimes DA, Schulz KF. Abortions that fail. Obstet Gynecol 1985; 66: 533-537.
  13. Ulmann A, Silvestre L, Chemama L, et al. Medical abortion of early pregnancy with mifepristone (RU486) followed by a prostaglandin analogue. Acta Obstet Gynecol Scand 1992; 71: 278-283.
  14. Bird DT. Medical abortion in Britain. Br J Obstet Gynaecol 1994; 101: 367-368.
  15. Rodger MW, Baird DT. Pre-treatment with mifepristone (RU486) reduces interval between prostaglandin administration and expulsion in second trimester abortion. Br J Obstet Gynaecol 1990; 97: 41-46.

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