Análisis de resultados «falsos negativos» para trisomía 21 en los programas de cribado combinado de primer trimestre: una herramienta para la mejora de la calidad

The occurrence of FN is caused by multiple factors. We found significant differences in maternal weight and NT, as well as borderline significance in differences of MoM of PAPP-A, therefore, it is essential to use the correct weight at the time of biochemical testing and, most important, ensure the quality of NT and PAPP-A measurement. Maternal age determines the previous risk and final result; so it is significant that our FN cases appeared in younger pregnant.