Integrating antenatal Down's syndrome screening

Statistical modelling is used to predict screening detection and false-posi tive rates for policies using different marker combinations and screening m odalities. Parameters are derived wherever possible from meta-analyses. Scr eening with four serum markers yields a similar detection rate in the first trimester as it does in the second, and both have a similar detection rate to that of ultrasound nuchal translucency screening. Ultrasound anomaly sc reening has a low detection rate. The integration of the different screenin g modalities can yield very high detection rates. Some methods of integrati on are preferable to others. The concurrent use of first trimester serum ma rkers and ultrasound nuchal translucency is the most practical. The combina tion of three modalities with nondisclosure of the intermediate results is more efficient, but the gain in detection is too small to warrant the wait for up to 4 weeks for results. The sequential use of modalities with interm ediate disclosure is more practical but will generate higher false-positive rates. Curr Opin Obstet Gynecol 13:175-181. (C) 2001 Lippincott Williams & Wilkins.