The "Consecutive Combined Test"--using double test from week 8 + 0 and nuchal translucency scan, for first trimester screening for Down syndrome.
OBJECTIVE
To test the performance of the "Consecutive Combined Test", applied on a high-risk population. The classic "Combined Test" (Double test (DT) and Nuchal Translucency (NT) measurement on the same day at app. week 12) gives detection rates (DR) for Down syndrome (DS) of 80-90% for false positive rates (FPR) of 5%. In affected pregnancies, however, the low PAPP-A level is more pronounced, the earlier in pregnancy. Thus, we hypothesized that the Double Test could be taken as early as from week 8 + 0, without compromising the excellent performance of the Combined Test. This "Consecutive Combined Test" allows for a centralised laboratory function.


METHODS
Inclusion criteria were maternal age > 35 years (80%) or a family history (20%). Double test was taken at a median gestational age (GA) = 10 weeks. NT was measured at GA = 11 + 0 - 13 + 6. A combined risk estimate of > 1:400 at birth was used as cut-off.


RESULTS
881 had the full test. Screen positive = 34. CVS with aneuploidy = 11 (6 trisomy-21, 5 others). FPR = 3.2%. Positive Predictive Value (PPV) = 17.6% for T-21.


CONCLUSIONS
The "Consecutive Combined Test" applied on a high-risk population seems to be highly efficient with a remarkably high PPV.
Schiøtt
Kirsten Marie
KM
Skejby University Hospital, Aarhus, Denmark. kms@dadlnet.dk
Christiansen
Michael
M
Petersen
Olav Bjørn
OB
Sørensen
Tina Lind
TL
Uldbjerg
Niels
N
D000328:Adult; D000782:Aneuploidy; D018997:Chorionic Gonadotropin, beta Subunit, Human / Q000097:blood; D004314:Down Syndrome / Q000175:diagnosis* / Q000000981:diagnostic imaging; D005260:Female; D005315:Fetal Diseases / Q000175:diagnosis* / Q000000981:diagnostic imaging; D006801:Humans; D008423:Maternal Age; D048208:Nuchal Translucency Measurement; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D011266:Pregnancy-Associated Plasma Protein-A / Q000032:analysis; D011296:Prenatal Diagnosis / Q000379:methods
D018997:Chorionic Gonadotropin, beta Subunit, Human; D011266:Pregnancy-Associated Plasma Protein-A