Hi and welcome to HCM Ultrasound findings associated with trisomy 21 may be divided into 2 groups. The first group comprises the major malformations associated with Down syndrome, including duodenal atresia and cardiac disease. The second group comprises the screening indicators, including brachycephaly, mild ventriculomegaly, macroglossia, abnormal facies, nuchal edema, echogenic/hyperechoic bowel, pyelectasis, and shortening of the limbs NT of less than 3.5mm is considered normal. As the NT increases, so does the risk of Down s and other chromosomal abnormalities. In your case it is 2.3mm which is normal. As your age also very important risk factor for downs syndrome. Amniocentesis is a prenatal test in which a small amount of amniotic fluid is removed from the sac surrounding the fetus for testing. The sample of amniotic fluid (less than one ounce) is removed through a fine needle inserted into the uterus through the abdomen, under ultrasound guidance. The fluid is then sent to a laboratory for analysis. Amniocentesis is more than 99 percent accurate in diagnosing downs syndrome. Its better you to go for amniocentesis and of its come positive for downs syndrome, your doctor will advice you to go for termination of pregnancy for your own good. Hope for the best Regards Dr Santosh