Abstract
We present a unique case of a 33-year-old gravida that was referred to our hospital with an umbilical vessel aneurysm presenting as a large placental cyst on ultrasound. Although the 20-week anomaly scan showed no structural abnormalities, routine fetal biometry scanning at 30 weeks of gestation revealed an abnormal placental cystic structure, located subchorionic under the umbilical cord insertion. Given the uncertainty of the origin of the structure's origin and its unpredictable evolution with possible adverse effect on the fetus, a cesarean section was performed delivering a healthy baby. Histopathological examination of the placenta showed an aneurysmal vein with thinning of the vessel wall and fragmented smooth muscle. Umbilical cord aneurysm represents an exceptionally rare placental anomaly, with umbilical vein aneurysms being associated with variable fetal mortality rates, ranging from those observed in uncomplicated pregnancies to 82% in documented cases. Therefore, a multidisciplinary approach is essential to optimize fetal outcomes.