Antenatal screening for cystic fibrosis

Antenatal screening for cystic fibrosis – Tips from Other Journals

Cystic fibrosis is one of the most common genetic diseases in Britain, and four common mutations are believed to be responsible for the majority of cases. It is technically possible to detect at least 80 percent of carriers by chromosomal analysis of cells taken from mouthwash samples. Bekker and colleagues examined the acceptability and feasibility of widespread screening for cystic fibrosis carriers in primary care.

During a 15-month period, 957 adults of reproductive age who were registered with a large general practice in London were screened. Tests to measure anxiety were also administered at the time of screening. Patients were invited to be screened by various methods, including direct mail and opportunistic screening whenever the patient made contact with the practice. The practice also received requests for screening from patients in other practices who had a family history of cystic fibrosis. The highest rates of screening (70 percent) were by opportunistic methods (i.e., patients waiting for office visits). Twice as many women as men were screened, and the uptake was higher among patients who were well educated and middle class.

Among those tested, 28 carriers were identified. No carrier couples were found when patients’ partners were tested, but five carriers were identified among 14 first-degree relatives who had also been tested. Twenty-five patients identified as carriers contacted either their family physician or the research team after receiving their results.

Patients who tested positive were significantly more anxious after learning their test results than those who tested negative, but their anxiety levels had resolved at three months after testing. Also, at three-month follow-up, about one-fifth of patients had some misunderstandings about the meaning of the test results. Despite counseling, these patients were not likely to recognize the limitations of the test.

The authors conclude that while there is not high public demand for screening for the cystic fibrosis carrier state, high uptake of screening can be achieved by enthusiastic health care workers. They caution that even with counseling about test results, inaccurate interpretations of test results are likely in a small but significant proportion of the population.

In a related study, Harris and colleagues investigated the feasibility of integrating screening for cystic fibrosis into antenatal care in general practice.

The study included pregnant patients of eight practices in northern England (total practice population was about 50,000, with 500 to 800 pregnancies per year). The average stage of pregnancy at first visit was eight weeks, and 90 percent of pregnant patients were seen before 14 weeks of gestation. Voluntary testing was offered to all pregnant patients. Discussions were supplemented with literature prepared for the project.

Of 244 pregnant women, eight were identified as carriers; five of the fathers were identified as carriers. Screening was declined by 11 pregnant women. One carrier couple was found. The couple had no history of cystic fibrosis and underwent extensive counseling before electing to have chorionic villus biopsy performed at nine weeks’ gestation. The fetus was normal but was subsequently miscarried. The couple requested prenatal diagnosis for subsequent pregnancies.

The authors believe that general practitioners may play an increasing role in routine voluntary screening for cystic fibrosis. They stress issues of patient acceptability, increased workload and cost, and draw attention to the need for quality integrated services to assist couples identified as carriers of potentially serious conditions. (BMJ, June 12, 1993, vol. 306, pp. 1580, 1584.)

COPYRIGHT 1993 American Academy of Family Physicians

COPYRIGHT 2004 Gale Group