[Maternal serum screening for congenital abnormalities and Down syndrome in Sønderjylland County. Eight years of experience].

From January 1991 to December 1998 second-trimester maternal serum screening (Doubletest and Tripletest) for malformations and Down syndrome has been offered to pregnant women younger than 35 years of age living in Sønderjyllands county, Denmark. Follow-up of all cases of chromosome abnormalities and severe foetal malformations identified pre- or postnatally has been carried out. A total of 17,023 women were screened. Sixty-eight percent (17/25) of Down Syndrome pregnancies were detected. Three percent of the screened women were offered an amniocentesis due to a calculated risk of DS greater than 1:400 at birth. The positive predictive value was 1:30. For the three-year period 1996-1998 (Tripletest) the results were more promising: 91% (10/11) were detected, 3.9% were offered an amniocentesis, the positive predictive value was 1:21. In the eight-year period 80% (8/10) of the spina bifida cases were detected, all the cases (6/6) of anencephaly and 75% (6/8) of abdominal wall defects. One point six percent of the screened women were offered an amniocentesis due to high risk of a neural tube defect. The results confirm that second trimester maternal serum screening is a reliable method for determining the risk of severe foetal malformations and Down syndrome.