CUT-OFF VALUE OF SOME CHROMOSOME DISORDERS WHEN APPLYING 3T FOMULA IN TRIPLE TEST IN NAM DINH

Abstract

Rationale: Using algorithms in triple test screening plays an important role in helping doctors and families make the right decisions on prenatal diagnosis; however, each algorithms requires appropriate values. Objectives: Determine the cut – off value of some chromosomal disorders when using 3T formula in triple test in Nam Dinh. Methods: Cross-sectional description on 991 triple tests of pregnant women examined at Obstetrics and Gynecology clinic in Nam Dinh in 2 years (2015-2016). Statistical algorithms were used to find appropriate screening thresholds. Results: 87.4% of the pregnant women were in the reproductive age group from 18-34. T21 index was calculated by 3T formula, which is closely related to the mother's age. In gerneral, chromosomal abnormalities accounted for 9.4% with pre-existing thresholds. Followings are screening cut off point appropriate for 3T formula of each chromosome disorder syndrome: Trisomy syndrome 21 was 1/538 (with maternal age from 18-34) or 1/100 (with maternal age <18 or> 34) ; Trisomy 18 syndrome was 1/1081; Trisomy syndrome 13 was 1/739.