title: Prospective experience with contingent screening strategy for Down syndrome in Estonia.
abstract: The purpose of this study was to establish the first-trimester screening for Down syndrome (DS) in Estonia and to evaluate the potential of a contingent screening in the population of pregnant women. A prospective cohort study included non-selected pregnancies during the programme of first-trimester screening for DS in a 4-year period at a single centre. The following screening tests were evaluated: measurement of nuchal translucency (NT) and serum screening [pregnancy-associated plasma protein A and free beta subunit of human chorionic gonadotropin (fβ-HCG)]; results were given as combined screening. After first-trimester screening, contingent screening protocol was used, and women were divided into three groups: high risk, low risk and an intermediate risk group. In the last group, a second-trimester triple test (AFP; total HCG and uE3) was also performed. The study group consisted of 3,194 non-selected pregnancies. In 1,387 (43.4%) women, first-trimester serum screening showed low risk (risk ≤ 1:5,000), and no future testing was performed, in 30 (0.9%) women screening test showed high risk (risk ≥ 1:50) and a diagnostic test was offered, and in 1,777 (55.7%) women repeated risk calculation in the second trimester was done. During the study period, there were 17 cases of trisomy 21, of which 15 (88.3%) were detected with the described screening programme. In conclusion, two-step contingent sequential screening is a better choice for Down syndrome screening in Estonia instead of previously used second-trimester screening, and it offers the advantage of earlier diagnosis.
authors.affiliation: Department of Paediatrics, University of Tartu, Tartu, Estonia, Kai.muru@kliinikum.ee.
authors.forename: Kai
authors.initials: K
authors.lastname: Muru
authors.forename: Mari
authors.initials: M
authors.lastname: Sitska
authors.forename: Karin
authors.initials: K
authors.lastname: Asser
authors.forename: Aivar
authors.initials: A
authors.lastname: Ehrenberg
authors.forename: Helle
authors.initials: H
authors.lastname: Karro
authors.forename: Katrin
authors.initials: K
authors.lastname: Ounap
authors.forename: Tiia
authors.initials: T
authors.lastname: Reimand