Which of the following is a common ultrasound finding associated with Trisomy 18?

Trisomy 18, also known as Edwards syndrome, presents a variety of ultrasound findings that can aid in the prenatal diagnosis of the condition. One of the notable ultrasound findings associated with Trisomy 18 is the presence of a single umbilical artery. This occurs when there is a failure of the usual two umbilical arteries to develop, leading to variations in fetal blood flow and potentially impacting fetal development.

The identification of a single umbilical artery is significant because it is more commonly observed in fetuses with certain chromosomal abnormalities, including Trisomy 18. In the context of this condition, it serves as a marker that should trigger further investigation and potentially a more comprehensive evaluation for associated anomalies.

Other findings such as polydactyly and echogenic bowel can occur in various conditions and are not specific markers for Trisomy 18. Holoprosencephaly, which involves brain malformation, is more closely associated with Trisomy 13 (Patau syndrome) rather than Trisomy 18. Thus, the presence of a single umbilical artery is a distinct and relevant finding related to Trisomy 18, making it a critical point for diagnosis and further assessment.