Enlarged Image for Clinical Update 2005

Left, Ultrasound images of fetal nuchal translucency give a measure of the thickness of the subcutaneous fluid at the back of the fetus's neck. In Down syndrome, the fetal nuchal translucency measure is abnormally large, as shown in this ultrasound of an 11-week fetus (arrow). Right, An 11-week fetus showing normal nuchal translucency (arrow). Other eary signs of Down syndrome in the first trimester are now being investigated as well, such as a missing fetal nasal bone.