19758085909520002004ONTDScreeningDown SyndromeAFP OnlyhCGFree Beta hCG1st Free Beta1st Papp-ANT1st Biochem/NTNBMaximizing1st Screening

1. 2.

1. NT( 11 13+6 )2. (18 )

1. 2. 3.

MarkerTimingDetection Rate

AFP ALONE > 15 weeks 20%AFP & hCG >15 weeks 60%AFP,hCG,uE3 >15 weeks 65-70%AFP,hCG,uE3,DIA >15 weeks 70-75%NT11-14 weeks70-80%NT, B-hCG, PAPP-A11-14 weeks>85%

false positive . 15 . 7

CVS or early amnio .

.

. 16-18

. . false-positive rates ( )

PAPP-A and Free B-hCG60-68% detection of DS90% detection of Tri 184.5% false positive rate

Some centers quote 87% detection of DS when combined with maternal age

Nuchal Translucency

> 3mm = 30% risk of aneuploidy

50-85% detection, 4.5% false positive

Also associated with CHD, skeletal abnormalities, and diaphragmatic hernia NT 3 (CVS ) .

PAPP-A and Free B-hCGOn average, baby with trisomy 21 will have 2.0 Mom for B-hCG and 0.4 MoM PAPP-A

Integrated test 4 (NT )Detection Rate false positive (4/4) . :

Stepwise Sequential test ( +NT ) . : . 95 False positive 5 ( ). .

( ) . NT

ACOGScreening program must meet specific criteria:

Trained, certified, monitored sonographers perform NT NT alone is not sufficient, biochemistry must be includedComprehensive genetic counseling must be offeredAccess to diagnostic testing if abnormal screen resultsRigorous continual evaluations