Which condition is most associated with aneuploidy when presented in isolation?

The condition that is most associated with aneuploidy when presented in isolation is cystic hygroma. Cystic hygroma is characterized by abnormal lymphatic vessel development and is often identified as a cystic mass in the neck region of a fetus.

Cystic hygromas are frequently associated with chromosomal abnormalities, particularly Turner syndrome (45,X) and Down syndrome (trisomy 21). Their presence alone can prompt genetic counseling and further investigations, like karyotyping, to assess for aneuploidy. The significant association of cystic hygroma with these chromosomal irregularities makes it a key indicator in prenatal screening for aneuploidy.

While other conditions like ventriculomegaly, hydrops fetalis, and choroid plexus cysts can also indicate genetic abnormalities or adverse outcomes, they are not as reliably correlated with aneuploidy when evaluated as isolated findings. For instance, ventriculomegaly can be linked to various conditions unrelated to chromosomal disorders. Hydrops fetalis can have multiple origins, including non-chromosomal factors such as infections or anemia. Choroid plexus cysts, while sometimes associated with trisomy 18, are commonly found in normal pregnancies