Umbilical artery aneurysm: prenatal diagnosis and management

An umbilical artery aneurysm is an extremely rare lesion. The purpose of this report is to describe the prenatal sonographic characteristics of such a lesion and potential obstetric complications.

A 26-year-old woman, gravida 2, para 1, at 30 weeks' gestation was referred for an ultrasound examination because of "an abnormality of the umbilical cord." An ellipsoid cystic lesion was noted in a single umbilical artery. Doppler and color flow Doppler examinations demonstrated nonpulsatile and turbulent blood flow within the lesion, consistent with a diagnosis of umbilical artery aneurysm. The aneurysm increased in size over time with a progressive decrease in amniotic fluid volume. Despite reassuring bi-weekly antenatal testing and planned delivery by 36 weeks' gestation, the fetus died in utero, probably because of acute umbilical venous compression by the aneurysm. Autopsy confirmed the presence of a large calcified aneurysm of a single umbilical artery. Dissection of the aneurysm demonstrated anatomical patency of the entire artery. The umbilical vein was histologically normal, as were sections of the artery.

Although extremely rare, an umbilical artery aneurysm is a potentially lethal anomaly. We recommend delivery as soon as fetal lung maturity is assured when this diagnosis is made prenatally.