BioEd Online

Scientists have pinpointed the deadly bacterium responsible for the death of four US women who underwent abortion induced by prescription medications. Medical experts now warn that such procedures might carry a greater mortality risk than surgical abortions.

Women often opt to take the so-called 'abortion pill' mifepristone, which is approved for use in early pregnancy, for privacy reasons; they can receive it from a doctor without having to visit an abortion clinic. Some women taking the medication also say that drug-induced termination feels more natural than the prospect of a surgical procedure.

Although mifepristone first became available in Europe in 1988, the US Food and Drug Administration (FDA) only approved the drug (also known as RU 486 and sold under the name Mifeprex) relatively recently, in September 2000. Since then the agency has strengthened the warning in the labelling of the drug to draw attention to the risk of complications associated with its use in terminating early pregnancies. This action was partly as a result of the four fatalities, which occurred from 2003 to 2005.

"These four cases show that there are risks of infections [associated with abortion medication], just as there is with surgical abortions," says Marc Fischer of the US Centers for Disease Control and Prevention in Atlanta, Georgia. He points out, however, that the risk seems to be linked to the overall procedure involving mifepristone, and not necessarily to the drug itself.

Bacteria to blame

In this week's issue of the New England Journal of Medicine¹, Fischer and his colleagues report that all four of the women who died succumbed to uterine infections caused by the bacterium Clostridium sordellii. This microbe caused fatal toxic shock syndrome in these women, along with one Canadian woman who had a similar abortion in 2001.

C. sordellii lives naturally in the human gut and in the vagina, but not the uterus. Fatal infections from the bacterium are very rare. How the microbe reached the uterine area of the affected women remains a mystery. Scientists do not have any causal evidence to link Mifeprex to the C. sordellii infections, a point echoed by New York-based Danco Laboratories, which market the drug in the United States.

"There has been no causal relationship established between the Mifeprex regimen and the deaths of the women discussed in the NEJM article," says Cynthia Summers, director of marketing and public affairs for Danco Laboratories.

US health authorities have also tested another drug involved in the treatment, taken after Mifeprex to clear the uterus, although it was initially developed to treat stomach ulcers. The investigation found no evidence of C. sordellii contamination, although investigators note that all of the infected women administered this dose vaginally, rather than orally. This method, they speculate, could have introduced the microbe into the body.

Weighing the risks

The reports of these deaths suggest that abortions induced by prescription drugs carry a notable risk, says Michael Greene, a former chairman of the FDA Reproductive Health Drugs Advisory Committee.

He says that more than 460,000 pregnancy terminations have involved mifepristone and calculates that the mortality risk of this procedure is around 1 in 100,000: ten times that of surgical abortions performed after fewer than eight weeks' gestation. Mifepristone is approved for the termination of pregnancies at fewer than seven weeks' gestation.

But the number of deaths is tiny, and data related to abortion are difficult to obtain because states have differing laws on record-keeping. So some say there may be 'statistical instability' in comparing risks of surgical and medical abortion. "What I would say is that they're both extremely low. I don't think that you can distinguish between them," says David Grimes of Family Health International, a non-profit organization based in Research Triangle Park, North Carolina.

"When one steps back and looks at the broader picture, both methods of early abortion are very safe... many times safer than carrying a pregnancy to term and orders of magnitude safer than illegal abortion," says Summers.