Second trimester maternal serum screening for fetal open neural tube defects and aneuploidy

Abstract

Maternal serum screening has been modified during the past 25 years and is now widely utilized during the second trimester to identify women at risk for fetal open neural tube defects (ONTDs), anencephaly, and trisomies 21 and 18. This statement replaces the 1994 and 1996 ACMG position statements on serum screening and discusses clinical guidelines for screening that complement the sections of ACMG’s Standards and Guidelines for Clinical Genetics Laboratories entitled “Prenatal screening for open neural tube defects” and “Prenatal screening for Down syndrome” (http://www.acmg.net).