Virginia officials backed off last week from requiring vaginal ultrasounds before abortions, but state legislators are still expected to pass a bill that mandates abdominal ultrasounds and adds other significant requirements for women seeking abortions.

In recent years, this common diagnostic tool has taken a greater role in abortion-related legislation. Seven states require ultrasounds before abortions. Twenty states regulate some aspect of ultrasound exams, including requiring abortion providers to give women the option to view the image or listen to the fetal heartbeat if an ultrasound is performed.

Eleven other states have legislation pending. If all of the measures pass, more than half of the states will have laws governing ultrasound exams before abortions. “I think we’re in the middle of a wave of ultrasound bills,” said Elizabeth Nash, a policy analyst with the Guttmacher Institute, which studies reproductive health.

In most states that require ultrasounds, as will be the case in Virginia, women must wait at least 24 hours between abortion counseling and the procedure and make at least two trips — one for the counseling and ultrasound, and another for the abortion.

Providers say scheduling of those trips — and not the ultrasound — has been the most cumbersome and costly effect of the law.

“In the majority of cases, these are working moms who have to cancel two days of work, arrange transportation twice and arrange child care twice,” said Amy Hagstrom Miller, who operates five clinics in Texas.

In Texas and Virginia, women who live more than than 100 miles from a provider would not have to make two trips.

“That is the practicality obstacle,” said Rosemary Codding, director of the Falls Church Healthcare Center. Those barriers prevent access to medical care, and then “you’re promoting illegal abortions somewhere else,” she said.

Despite the controversy over what type of ultrasound would be required in Virginia’s bill, both abdominal and vaginal ultrasounds are, in fact, used by most abortion providers. They are the most accurate tool for determining the development stage of a fetus, doctors said.

“It’s pretty much common practice,” said Willie Parker, a doctor who performs abortions in the Washington region and Philadelphia.

Abdominal ultrasounds are the most common. The vaginal ultrasound is mainly used in the earliest stages of pregnancy — between four and six weeks — when an abdominal ultrasound is unlikely to produce an image.

Only about one-third of abortions are performed at six weeks or less, according to 2005 data from the U.S. Centers for Disease Control and Prevention.

Providers need to know how far the pregnancy has progressed to ensure that an abortion is taking place within a state’s legal time frame, that medically appropriate methods are being used, and to rule out ectopic pregnancies.

Sixty percent of abortions are done in the first nine weeks of pregnancy, when medication abortions are most effective, doctors said. More than 88 percent of the 1.2 million abortions performed each year in the United States occur in the first trimester of pregnancy. Most doctors will not perform them beyond 22 or 24 weeks.

Texas, which has the most restrictive ultrasound law in effect, also requires the person doing the ultrasound to be the same person who performs the abortion. That adds to the scheduling problem. In many cases, doctors have to fly from clinic to clinic, Hagstrom Miller said.

In Virginia, the Senate is expected to vote on an amended bill this week that mandates abdominal ultrasounds, but leaves the use of vaginal ultrasounds up to the doctor and woman. The bill was amended after protests in Richmond and spoofs by late-night comedians turned the national spotlight on Virginia. The original measure would have required women to undergo a vaginal probe. Gov. Robert F. McDonnell (R) has said he will sign the bill if it is amended. The law would go into effect July 1.

Proponents say the ultrasound requirement is intended to give women accurate, necessary information.

Ultrasounds “are not done 100 percent of the time,” said Olivia Gans, president of the Virginia Society for Human Life and an outreach director of the National Right to Life Committee. “This is to protect the other 2 percent,” she said. A doctor performing an abortion might not do an ultrasound if the patient has had one somewhere else.

Mandatory ultrasounds also make it easier to require that women be given the option of seeing the image. That additional information may help women make their decision.

Abortion rights activists say mandating ultrasounds violates the doctor-patient relationship and also assumes that women don’t know what they’re doing. About 60 percent of women having abortions already have at least one child, according to the Guttmacher Institute.

“This is really a bill that is about shaming and demeaning women seeking reproductive health,” said Laura Meyers, chief executive officer of Planned Parenthood of Metropolitan Washington.

Most women who get abortions don’t have health insurance. Of those who do, less than half use it because they don’t want employers or others to know, according to Guttmacher.

The cost of an abortion varies. In 2009, the average charge for a surgical abortion at 10 weeks was $543. At the Falls Church center, the charge ranges from $325 to $475, but includes the cost of ultrasound, if needed. At other facilities, reproductive rights activists estimate that an ultrasound requirement can add $50 to $200. In Texas, the $400 cost of the abortion has remained the same at her clinics, but some have added $25 to cover the extra doctor visit, Hagstrom Miller said.

As in other states, Virginia’s rule would require that a printout of the ultrasound image be placed in a woman’s medical record, regardless of whether she views it. In Texas, even if patients decline to view the image or listen to the fetal heartbeat, the law requires doctors to read a detailed description of the physical characteristics of the fetus, including any limbs or internal organs.

That process has not deterred women from seeking abortions, Hagstrom Miller said.

The impact of the provisions on the number of abortions is unclear, according to advocates on both sides. In several states that require women to make two trips, the number of abortions has fallen, according to the Guttmacher Institute. But in Louisiana, which requires women to make two trips and in 1999 required ultrasounds, the number of abortions has risen, from 13,100 in 2000 to 14,960 in 2008, according to the most recent data available.

The number of abortions being done in the United States has remained steady in recent years. Abortion opponents say that educational and legislative efforts have had an impact, but “pinpointing a particular piece of legislation is difficult,” said Carol Tobias, president of the National Right to Life Committee.

Abortion rights supporters say other forces are at work, including the dwindling number of providers and clinics, and increasing harassment of providers.