Among the following, the most sensitive USG finding of Trisomy 21 is:

b. Thickened nuchal fold(Ref: Textbook of Perinatal Medicine, 2nd Edition, edited by Asim Kurjak, Frank A. A. Chervenak, pg 835, Nelson's 20/e p 610-615)Prenatal USG markers of Down syndrome include thickness of nuchal fold (75% sensitive), absence of nasal bone (58% sensitive), cardiac abnormalities, duodenal atresia, shortened femur, shortened humerus, renal pyelectasis, a hyperechogenic bowel, and a choroid plexus cyst.