Trisomy 21 (Down syndrome) is the most common chromosomal abnormality. Sonographic findings in fetuses with Down syndrome include both structural abnormalities and nonstructural abnormalities or "markers." These markers are known as "soft markers" of aneuploidy. These markers are nonspecific, often transient. The most commonly studied soft markers of aneuploidy include a thickened nuchal fold, long bones shortening, mild fetal pyelectasis, echogenic bowel, echogenic intracardiac focus, FMF angle > 90 degrees, pathologic velocity of Ductus venosus and choroid plexus cyst.