Evaluación del índice de riesgo del primer trimestre en casos de embarazo múltiple con presencia de un feto perdido

The risk index is not calculable due to the loss of one fetus. The levels of the free fraction of the beta subunit of human chorionic gonadotropin (β-hCG) in serum are not affected but there is a significant increase in the levels of pregnancy associated plasma protein-A (PAPP-A), which depends on the time since fetal loss; so the serum levels cannot be regarded neither as an isolated fetus or as 2. Therefore to assess the risk of the first-trimester combined screening test, it is recommended to estimate the fetal nuchal translucency thickness (NT) and β-hCG, or just only NT, also considering the median multiples (MoM) within the normal limits.