Women who test positive on a maternal serum alpha-fetoprotein (MSAFP) test are offered ultrasound examination to rule out other causes of elevated MSAFP such as other congenital anomalies, intrauterine growth retardation, multiple gestations, or fetal demise. When ultrasound does not provide an explanation for the elevated MSAFP, an amniocentesis should be offered. To assess the validity and usefulness of MSAFP measurement in detecting NTDs, it was applied to 6443 consecutive singleton pregnancies. A total of 262 of these women tested positive for MSAFP. After delivery, the presence of a NTD was detected in 17 of the newborns of the women who had tested positive during their pregnancies, but also in 5 of the newborns whose prenatal MSAFP was negative. From these data, screen a 2x2 contingency table.

Women who test positive on a maternal serum alpha-fetoprotein (MSAFP) test are offered ultrasound examination to rule out other causes of elevated MSAFP such as other congenital anomalies, intrauterine growth retardation, multiple gestations, or fetal demise. When ultrasound does not provide an explanation for the elevated MSAFP, an amniocentesis should be offered. To assess the validity and usefulness of MSAFP measurement in detecting NTDs, it was applied to 6443 consecutive singleton pregnancies. A total of 262 of these women tested positive for MSAFP. After delivery, the presence of a NTD was detected in 17 of the newborns of the women who had tested positive during their pregnancies, but also in 5 of the newborns whose prenatal MSAFP was negative. From these data, screen a 2x2 contingency table.