The effect of inherited thrombophilia on second trimester combined aneuploidy screening test markers.

Abstract

To determine whether inherited thrombophilia affects components of second trimester combined aneuploidy screening test. A case-control study was performed between 1 December 2010 and 1 February 2012, at a tertiary referral hospital. Singleton pregnancies with inherited thrombophilia that underwent second trimester (16-19(+6) week) combined aneuploidy screening test were included in the study. Maternal serum alfa fetoprotein, unconjugated estriol, human chorionic gonadotropin levels and multiple of median (MoM) levels were compared between the study group and controls. Within the study period, 18,943 women with singleton pregnancies had a combined second trimester aneuploidy screening test at our institution. Among these, 26 women met the criteria of thrombophilia. A control group that comprised 275 women with similar gestational age was generated, using a 1:1 ratio. Unconjugated estriol MoM levels were significantly lower in women with inherited thrombophilia (p=0.02). But there was no statistically significant difference for unconjugated estriol levels, human chorionic gonadotropin, alfa fetoprotein and their MoM levels. Our study suggest that in patients with hereditary thrombophilia a new correction factor should be used, when calculating unconjugated estriol MoM value, which is one of the markers of second trimester aneuploidy screening test.