RÉSUMÉ
Background: Down syndrome is a developmental disorder caused by an extra copy of chromosome 21, is a condition in which extra genetic material causes delays in the way a child develops, both mentally and physically. It affects about 1 in every 700 babies. The fetus having high risk for Down syndrome (OS) can be detected early by ultrasound. Objectives: The aim of the study is to find out some ultrasound markers that relate to OS fetus. Subjects and method: A descriptive study was carried out on 612 pregnant women with fetus \ufffd?12 weeks by ultrasound to detect abnormal markers in fetus. The fetus were diagnosed Down syndrome by analysis chromosome from amniocyte and monitor up to the neonate. Then, finding out association between OS fetus and ultrasound markers. Results: Among 612 pregnant women,36/12 pregnant women had abnormal imaging in fetus, 11/12 pregnant women had OS fetus. There were 12 pregnant women detected OS fetus. 6/12 OS fetus associated with the maker of nuchal skin fold (cut off 2: 3mm at the first trimester and 2: 6 mm at the second trimester): Detection rate (DR) was 50%; false positive rate (FOR): 0,83%. 3/12 OS fetus associated with the marker of duodenal atresia. DR was 25%; FOR: 0%. Conclusions: The two common markers associated with OS fetus: \r\n', u'the first marker was nuchal skin fold (with cut off 2: 3mm at the first trimester and > 6 mm at the second trimester) and the second marker was duodenal atresia. \r\n', u' \r\n', u'