What prenatal feature is specifically associated with Noonan Syndrome?

Cystic hygroma is a prenatal ultrasound finding that is specifically associated with Noonan Syndrome. This condition is characterized by a spectrum of developmental anomalies, and the presence of cystic hygroma indicates an accumulation of lymphatic fluid, often observed in the neck region during prenatal imaging. It is important to recognize that cystic hygroma can also be seen in other chromosomal and genetic disorders; however, its notable association with Noonan Syndrome makes it a distinguishing feature in the context of this condition.

Microcephaly, large kidneys, and omphalocele can be present in various congenital syndromes and conditions but are not specifically tied to Noonan Syndrome in the same way cystic hygroma is. Therefore, while the other options may appear in different contexts, they do not reflect the characteristic prenatal feature that is strongly linked to Noonan Syndrome as cystic hygroma does.