Objective: Presentation of prenatal diagnostics results in the year 1998 and their comparison with the period 1990 - 1997. Design: A retrospective study. Setting: Subchair of Medical Genetics, Postgraduate Medical Institute, Vídeňská 800, Praha 4, Czech Republic. Methods: Processing of prenatal diagnostics data obtained from departments of Medical Genetics from all the Czech Republic. The comparison with livebirths with congenital malformation was made possible using the data from Statistics Reports „Congenital malformation in a foetus/new- born“ which are filed in the Institute of Health Information and Statistics. For a comparison on the international level the data published by the International Clearinghouse for Birth Defects Monitoring Systems were used. Results: 553 foetuses with congenital malformation were diagnosed in 1998. In the same year, 406 pregnancies were terminated from this reason. Totally, 445 particular malformations were found in the above mentioned foetuses. Most often, inborn chromosomal aberrations (and Down Syndro- me especially) were detected. Down Syndrome itself was diagnosed in 101 cases, out of which in 98 cases the pregnancy was terminated. Taking into account 61 cases of Down Syndrome in livebirths in 1998, the sensitivity of prenatal diagnostics of this defect is 61.64%. Finally, a compa- rison of our results with data from different congenital malformation registers all over the world was made. Conclusion: An increase of the prenatal diagnostics of congenital malformation as well as its improvement has taken place in the Czech Republic in last years. This improvement is accompa- nied by an increase of the number of prenatally diagnosed cases and also by an increase of the number of terminated pregnancies as its consequence. An incidence of severe congenital malfor- mations therefore decreases in livebirths. An efficiency of prenatal diagnostics is fully comparab- le to the results published by major congenital malformation registers worldwide.

        Key words: prenatal diagnostics, secondary prevention, congenital malformation, Down syndro- me, sensitivity