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

Abstract

Background and purposeTo justify an accurate assessment of the first-trimester combined screening test, in special cases of twin pregnancies with a vanishing twin; because the increase in such cases specially is being seen in pregnant women undergoing in vitro fertilization techniques. Patients and methodsWe report a case of biamniotic bichorionic twin pregnancy with loss of the first fetus at week 12. Prenatal screening was asked in wich it couldn’t been estimated the risk index for the first trimester screening test. Discussion and conclusionsThe 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.