<P> Tests for neural tube defects include ultrasound examination and measurement of maternal serum alpha - fetoprotein ( MSAFP ) . Amniotic fluid alpha - fetoprotein ( AFAFP ) and amniotic fluid acetylcholinesterase ( AFAChE ) tests are also used to confirming if ultrasound screening indicates a positive risk . Often , these defects are apparent at birth , but acute defects may not be diagnosed until much later in life . An elevated MSAFP measured at 16 -- 18 weeks gestation is a good predictor of open neural tube defects , however the test has a very high false positive rate , ( 2 % of all women tested in Ontario , Canada between 1993 and 2000 tested positive without having an open neural tube defect , although 5 % is the commonly quoted result worldwide ) and only a portion of neural tube defects are detected by this screen test ( 73 % in the same Ontario study ) . MSAFP screening combined with routine ultrasonography has the best detection rate although detection by ultrasonography is dependent on operator training and the quality of the equipment . </P>
<P> Tests for neural tube defects include ultrasound examination and measurement of maternal serum alpha - fetoprotein ( MSAFP ) . Amniotic fluid alpha - fetoprotein ( AFAFP ) and amniotic fluid acetylcholinesterase ( AFAChE ) tests are also used to confirming if ultrasound screening indicates a positive risk . Often , these defects are apparent at birth , but acute defects may not be diagnosed until much later in life . An elevated MSAFP measured at 16 -- 18 weeks gestation is a good predictor of open neural tube defects , however the test has a very high false positive rate , ( 2 % of all women tested in Ontario , Canada between 1993 and 2000 tested positive without having an open neural tube defect , although 5 % is the commonly quoted result worldwide ) and only a portion of neural tube defects are detected by this screen test ( 73 % in the same Ontario study ) . MSAFP screening combined with routine ultrasonography has the best detection rate although detection by ultrasonography is dependent on operator training and the quality of the equipment . </P>
when can a neural tube defect be detected
when can a neural tube defect be detected
An elevated MSAFP measured at 16 -- 18 weeks gestation is a good predictor of open neural tube defects
An elevated MSAFP measured at 16 -- 18 weeks gestation is a good predictor of open neural tube defects