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First‐trimester combined screening for trisomy 21 in a predominantly Chinese population
Author(s) -
Leung T. Y.,
Chan L. W.,
Leung T. N.,
Fung T. Y.,
Sahota D. S.,
Spencer K.,
Lau T. K.
Publication year - 2007
Publication title -
ultrasound in obstetrics and gynecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.202
H-Index - 141
eISSN - 1469-0705
pISSN - 0960-7692
DOI - 10.1002/uog.3893
Subject(s) - trisomy , medicine , fetus , obstetrics , pregnancy , population , pregnancy associated plasma protein a , gestation , gynecology , down syndrome , nuchal translucency measurement , aneuploidy , first trimester , biology , genetics , chromosome , environmental health , psychiatry , gene
Objective To examine the effectiveness of first‐trimester fetal trisomy 21 screening using a combination of maternal age, nuchal translucency thickness (NT) and maternal serum free beta‐human chorionic gonadotropin (β‐hCG) and pregnancy‐associated plasma protein‐A (PAPP‐A) levels in a predominantly Chinese population in Hong Kong. Methods This was a prospective study over a 1.5‐year period of 2990 women who underwent combined screening for trisomy 21 between 11 + 0 and 13 + 6 weeks of gestation in a university fetal medicine unit. NT was measured according to the criteria set by The Fetal Medicine Foundation (FMF), maternal serum free β‐hCG and PAPP‐A levels were measured, and the risk of trisomy 21 was calculated using The FMF's algorithm. Fetal karyotyping was advised when the risk was 1 : 300 or above. All subjects were followed up for pregnancy and fetal outcome. Results Of the 2990 women who underwent the screening program, 99% were Chinese. There were 57 twin pregnancies, giving a total of 3047 fetuses. Thirty‐one percent of the women were 35 years old or above. One hundred and eighty‐five (6.1%) fetuses were screen‐positive; this included 14 cases of trisomy 21 and 17 cases of other chromosomal abnormalities. The positive predictive value was 16.7%. Among the 2862 screen‐negative fetuses, only 18 (0.6%) cases had an unknown fetal outcome. There were no cases in which trisomy 21 was missed and the infant was liveborn. Conclusion First‐trimester combined screening for fetal trisomy 21 is highly effective among Chinese subjects. Copyright © 2006 ISUOG. Published by John Wiley & Sons, Ltd.