Róbert Dankovčík, Stela Muránska, Peter Urdzík, Andrea Grešová, Anna Plichtová, Marek Dudáš
The authors analyze prenatal screening tests for detection of foetal chromosomal abnormalities. Sensitivities of individual tests are compared especially with the triple test, which is the most frequently used prenatal screen in Slovakia. The goal was to determine the upper limit of the borderline risk (so-called gray zone) where the majority of undiagnosed chromosomal abnormalities are found. Mathematical recalculations have determined the borders of the gray zone to 1 : 251 and 1 : 600. Pregnancies falling within this range are recommended for a detailed sonographic examination, so-called genetic sonogram, for the purpose of the risk re-calculation. This strategy enables to increase the sensitivity of prenatal screening.