Abstract

The current report provides a survey of 8-year experience of the serum screening of trimester II in Estonia in 1999–2006. Maternal serum screening (double/triple test) of women aged <= 35/37 years started in autumn 1998 in Tartu, in 2000 in southern Estonia, in 2001 in Tallinn and only in 2003 in the whole of Estonia. In 2006, 91% of pregnant women in Estonia were monitored. The proportion of the pregnancies screened varied from 48% in eastern Estonia to ~ 100% in Tartu and Tallinn (the two biggest cities in Estonia). During the 8 years (1999–2006) altogether 60 970 screening tests were performed. Positive serum screening was an indication for amniocentesis (fetal karyotyping) in 2904 (4.76%) cases. Chromosomal abnormalities were detected in 82 (1:36) cases, and Down’s syndrome (DS) in 37 (45%) cases.
Detection rate (DR) i.e. the proportion of fetuses affected by Down’s syndrome, identified by a screening test or a combination of screening tests. In the study period (1999–2006) the DR of serum screening (double/triple test) in Estonia was 57.8%. In this period 30.3% of DS cases in the age group under under 35/37 years were diagnosed prenatally. In the advanced maternal age risk group chromosome anomalies have been screened since 1995. During the 12-year period 68% of the DS cases were diagnosed prenatally.
Incidence of Down’s Syndrome has decreased in Estonia after the introduction of prenatal screening was started: the provisional incidence of DS was 1: 684 and after prenatal screening (1995–2006) the incidence of DS is 1: 980 in live birth. During the period 1995–2006 when prenatal diagnosis was used in Estonia 46.2% of DS cases were diagnosed prenatally. We consider our experience in serum screening successful but a more efficient screening strategy is needed in the future. In 2008 an integrated test providing risk assessment in trimester II (triple test) in combination with nuchal translucency in trimester I will be introduced in Estonia.