Offer CF carrier screening to all high-risk couples: discuss testing during preconceptional counseling or at the first prenatal visit

OB/GYN News, Nov 1, 2001 by Kate Johnson

Physicians seeing patients for preconception or prenatal counseling should now be advising them about cystic fibrosis carrier screening, according to the American College of Obstetricians and Gynecologists.

Recommendations released by ACOG in September advise that screening should be offered to all white and other high-risk couples, preferably before pregnancy or at least at the first prenatal visit.

"Physicians are going to have to educate themselves because some of this information is either new or complex, and they will have to find a way to incorporate this into their routine visits," said Dr. Michael Mennuti, ACOG secretary and professor of ob.gyn., human genetics, and pediatrics at the University of Pennsylvania, Philadelphia.

Until now, ACOG has recommended offering cystic fibrosis (CF) carrier screening to couples only if one partner has the disease or a family history of CF. Under the new guidelines, these groups should continue to be offered screening.

The ACOG guidelines come 4 years after a 1997 National Institutes of Health consensus statement recommending that all couples who are planning a pregnancy or seeking prenatal care be screened for CF--a time lag that concerns Dr. Aubrey Milunsky, professor of human genetics, pediatrics, and ob.gyn. and director of the Center for Human Genetics at Boston University.

"This test represents simply one of an increasing number of available tests that are useful to the preconception patient, and it's taking a long time for organizations like ACOG to come out with position papers, which secure the health and welfare of patients at large. This is a major concern," he said.

ACOG's guidelines refine the NIH recommendations by making a distinction between different ethnicities. "The incidence of CF carriers varies between ethnic groups with the most common incidence, roughly 1 in 25, among Caucasians and a much lower incidence in African Americans, Hispanics, and Asians," Dr. Mennuti said.

ACOG advises offering CF carrier screening to white patients, because they are at higher risk. Other ethnic groups should simply be advised that the test is available.

ACOG has mailed to all its members both clinical and laboratory guidelines for the screening, as well as two patient information pamphlets.

The guidelines will probably not be put into practice immediately by all physicians, experts say "There's no doubt it will take some time to be adapted into clinical care, but it's clear that the time is appropriate to start doing this," said Dr. Ronald Wapner, director of reproductive genetics and maternal-fetal medicine and vice chair of ob.gyn. at MCP Hahnemann University Philadelphia.

Although CF carrier screening is best done before a woman becomes pregnant, studies show that interest in screening before pregnancy has been limited, according to AGOG.

"Preconception counseling rarely occurs in this country But doctors draw routine labs at the patient's first prenatal visit, and this is where they could fit the CF screen in," Dr. Wapner commented.

ACOG suggests sending the information pamphlets to couples before this initial visit, so they have time to make an informed decision about whether to have the test.

If a couple wants testing, physicians must decide whether to test both partners at the same time or to start with the patient and only proceed to her partner if she has a positive result. ACOG says that either screening method may be used.

If either partner tests positive for a CF gene mutation, this means they are a CF carrier; a baby must inherit two mutations of the CF gene to be affected by the disease. If both partners are carriers, they have a one-in-four chance of conceiving a baby with CF. If only one partner is identified as a carrier, the risk of having an affected baby still is not zero.

"The standard test screens for 25 of the most common mutations of the cystic fibrosis gene. But there are actually more than 1,000 known mutations," he said. ACOG advises that all posttest counseling involving a positive CF gene mutation requires "special knowledge of CF with regard to calculation of genetic risk, treatment options, range of severity and prognosis." In general, these cases would be referred to a genetic counselor. However, the primary care physician should be prepared to offer at least some basic counseling, said Dr. Charles Lockwood, professor and chair of ob.gyn. at New York University New York.

"This is a complicated disorder. Hundreds of mutations and different combinations of mutations produce different manifestations. ... Physicians need to at least understand that there is no simple answer when a couple asks, 'What will our baby be like?' "said Dr. Lockwood, who is also chair of the ACOG Committee on Obstetric Practice.

With a broadened scope of people being offered CF carrier screening, some physicians are uncertain about whether the tests will be covered by insurance. But Mohit Chose, a spokesman for the American Association of Health Plans in Washington, said that in general, plans cover CF screening if it is recommended by a doctor.