Women seeking medical abortion, sometimes called the “abortion pill,” often first undergo an ultrasound test, but a new study suggests that may be an unnecessary step.

In the U.S., medical abortions can be performed within nine weeks of the first day of a woman’s last menstrual period. Most medical abortions involve taking the drug mifepristone (Mifeprex) followed by misoprostol, which causes the womb to contract.

There are no official guidelines stating that women should first receive an ultrasound. But because ultrasound is the most precise way to determine how far along a pregnancy is, it has become common practice for providers to perform one. Most women who seek the abortion pill at Planned Parenthood clinics, for instance, undergo ultrasound.

However, ultrasound adds to the cost of medical abortion, which in the U.S. ranges from $350 to $650, and may be more depending on what tests or exams are done, according to Planned Parenthood.

And ultrasound may not even be available in some parts of the world. So the common belief that women need an ultrasound may be a barrier to receiving a medical abortion, according to the researchers on the new study, led by Hillary Bracken of Gynuity Health Projects in New York City.

Gynuity is a non-profit research organization that focuses on reproductive health services.

Bracken and her colleagues tested whether a woman’s estimate of her last menstrual period, along with a physical exam, is enough to judge her eligibility for an early abortion using mifepristone and misoprostol.

The study, published in the obstetrics journal BJOG, included 4,484 women seeking the abortion pill at any of 10 U.S. family planning clinics, including eight Planned Parenthood clinics.

Providers at the study sites - most often nurse-midwives, nurse practitioners or physician assistants - asked the women to give, or estimate, the date of their last menstrual period and performed physical exams. The women then underwent ultrasound.

Overall, only 1.6 percent of the women would have been given the abortion pill beyond the standard nine weeks if their providers had relied on their estimates and a physical exam alone.

And even in those cases, all of the women except for one were within the 11th week of their last menstrual period - a point at which, studies show, the effectiveness of medical abortion is still high, without an increased risk of complications.

Overall, medical abortion is effective 97 percent of the time, with failed attempts followed up with a surgical abortion. After the ninth week of pregnancy, that effectiveness may begin to wane, “but it is not a steep drop-off,” Bracken said in an interview. “Any reduction in efficacy would be gradual.”

The findings, she said, indicate that doctors and other providers who lack ultrasound equipment can still “feel safe” in offering medical abortion. And that could help broaden access to medical abortion in rural parts of the U.S., as well as developing countries where ultrasound would be largely unavailable.

Among the women who should not have a medication-induced abortion are those with an ectopic pregnancy, where the embryo grows outside of the uterus; or a molar pregnancy, an uncommon condition in which the placenta develops into an abnormal mass of cysts.

In the current study, providers used questions and a physical exam to “flag” women who might have an ectopic or molar pregnancy. Overall, 32 women were flagged; further tests confirmed an ectopic pregnancy in nine, and a molar pregnancy in two.

This study, Bracken said, was not specifically designed to study the question of whether non-ultrasound screening can reliably pick up cases of ectopic or molar pregnancy.

Future studies, she and her colleagues write, should compare the relative effectiveness of clinical screening - based on patient history and physical exams - and ultrasound screening for early ectopic and molar pregnancies.

It’s estimated that up to two percent of pregnancies in the U.S. are ectopic, and about one in 1,000 are molar.

When the abortion pill was approved in the U.S. in 2000, it was expected to broaden access to early abortion, in part because it could be prescribed by a woman’s own doctor no matter where she lived.

But a study last year found that in 2005, 96 percent of U.S. providers who wrote prescriptions for the abortion pill were in metropolitan areas, while 3 percent were in “micropolitan” areas (with 10,000 to 50,000 inhabitants) and only 1 percent were in small cities and towns.

It also found that in recent years, most prescriptions have been given at centers that also provided surgical abortions, with family doctors accounting for only about 11 percent of prescriptions.

SOURCE: BJOG, online November 23, 2010.