Estudio descriptivo del cribado de cromosomopatías en el primer trimestre de la gestación, en el Hospital Clínico San Carlos de Madrid, España

Abstract

Background: Screening for aneuploidies, mainly trisomy 21, during the first trimester of gestation, was introduced in the '90s and is based on a calculation of the risk through the combination of maternal age, nuchal translucency (NT) and biochemical parameters (PAPP-A and fßHCG). By means of this combination we can obtain a detection rate for aneuploidies of 85-90%, with a false positive rate of 5%. Objective: To describe our population and analyze our results related to combined screening for aneuploidies, during the period of time it has been performed in our hospital. Methods: Observational study of all pregnant women who attended Hospital Clínico San Carlos for screening of chromosomopaties during first trimester of gestation, from July 1999 to December 2009. Results: Sample size was 21,194 single pregnancies, with 12,5% of women with more than one gestation, and 141 cases of aneuploidy (6,6‰). We describe the characteristics of our population and the distribution of the parameters studied. Combined screening had a detection rate of 70% with a false positive rate of 2,3%. Conclusion: Screening for aneuploidies during first trimester of gestation, in Hospital Clínico San Carlos, has a lower detection rate than previously reported. However, the false positive rate is very low.