A fetus with trisomy 13 may have increased nuchal translu­cency in the rst trimester. A proboscis may be identied in the rst trimester. Fetuses with trisomy 13 typically have multiple anomalies. The most common striking anomalies are central nervous system anomalies, including holoprosencephaly (Fig­ure A) and other severe central nervous system anomalies such as agenesis of the corpus callosum, ventriculomegaly, and cer­ebellar anomalies. There are often concomitant midline facial anomalies that can vary from cyclopia to severe median cleft lip (Figure B). Documentation of other anomalies is less criti­cal. However, other anomalies include cardiac defects such as VSD or atrial septal defect or various hypoplasias such as aortic atresia and hypoplastic left heart (Figure C). Renal anomalies include echogenic kidney with cystic dysplasia. Most omphalo­celes contain only bowel and are small. Trisomy 13 and trisomy 18 are commonly associated with IUGR with polyhydramnios. There is a high incidence of cardiac echogenic foci in trisomy 13 compared with some other trisomies. In addition, muscu­loskeletal abnormalities including IUGR and clubfeet (Figure D) are seen, although many of these abnormalities, including rocker-bottom feet or clenched hands, are more often seen with trisomy 18.