Prenatal Testing for Cystic Fibrosis in the Central Denmark Region (2012-2023)

Cystic fibrosis (CF) is a severe genetic disorder with a carrier frequency of 1 in 30. In Denmark, prenatal testing is offered when there is a family history of CF or ultrasound anomalies suggest an increased risk of the disease. This study evaluates indications for prenatal CF testing and their outcomes.

Clinical indications and genetic results were analyzed for pregnancies undergoing CF testing in the Central Denmark Region between August 2012 and 2023. The data were categorized according to clinical indication.

Among 302 prenatal CF tests, echogenic bowel (EB) was the most frequent (44.7%, N = 135), leading to identification of one CF-affected fetus (0.7%). The second most common indication was EB together with non-CF-associated ultrasound findings (29.5%, N = 89), with no CF-affected fetuses. Known CF predisposition due to family history (15.6%, N = 47) identified five affected fetuses (10.6%) and 25 carriers (53.2%). No CF cases were detected in other included groups (N = 31).

These data show that EB has a low positive predictive value for cystic fibrosis in the fetus (1:230) in a country with combined first-trimester screening but no systematic preconception or prenatal screening program for cystic fibrosis. Although the relative risk is increased compared to the general population (1:2,500), EB appears to be a marker of limited clinical utility. In settings without dedicated CF screening strategies, this underscores the importance of considering the most effective allocation of diagnostic resources.