Cord Varix

Abstract

Umbilical vein varix (UVV) is a rare, idiopathic, focal dilatation of the umbilical vein, either within the intraamniotic portion of the umbilical cord or within the fetal abdomen. On ultrasound (US), UVV appears as a round or fusiform anechoic structure that is located either within the umbilical cord or within the fetal abdomen, inferior to the fetal liver and close to the anterior abdominal wall. Color flow, power Doppler, and pulsed wave Doppler US are useful to confirm the vascular nature of this lesion by showing venous flow in its lumen. Although the precise etiology of UVV is unknown, it has been speculated that any condition that increases venous pressure could potentially lead to dilatation of the extrahepatic portion of the umbilical vein because this anatomic region is the weakest area of umbilical circulation. Another suggested mechanism is an intrinsic weakness of the umbilical vein wall that subsequently leads to venous dilatation and the development of the varix. UVV is associated with a high rate of fetal anomalies and a potentially increased risk of fetal demise. The finding of a UVV should prompt a thorough search for other structural malformations and potentially aneuploidy testing. Serial growth measurements and antenatal surveillance are also recommended. There are currently no prenatal or postnatal treatment options for fetuses with UVV; however, due to the association with intrauterine fetal demise, early term delivery should be considered.

Keywords

varix, cord, umbilical vein

Introduction

Although umbilical vascular anomalies are congenital malformations seen commonly, venous abnormalities of the umbilical vein, such as an umbilical cord varix, are rare. The widespread use of routine sonography has facilitated the prenatal diagnosis of umbilical vein varix (UVV), the clinical significance of which remains unclear.

Disorder

Definition

UVV is a rare, idiopathic, focal dilatation of the umbilical vein, either within the intraamniotic portion of the umbilical cord or within the fetal abdomen.

Prevalence and Epidemiology

UVV is a rare entity, representing approximately 4% of umbilical cord malformations. In a retrospective review, Byers et al. reported an incidence of 1.1 : 1000 pregnancies. These lesions have been reported more commonly in the umbilical cord than in the fetus. In cases of intraabdominal UVVs, extrahepatic varices are more common than intrahepatic varices.

Etiology, Pathophysiology, and Embryology

The etiology of UVV is unknown. It has been speculated that any condition that increases venous pressure could potentially lead to dilatation of the extrahepatic portion of the umbilical vein because this anatomic region is the weakest area of umbilical circulation. Another proposed etiology is an intrinsic weakness of the umbilical vein wall, which subsequently leads to venous dilatation and the development of the varix.

UVV is associated with a high rate of fetal anomalies and intrauterine fetal demise, but published series report large differences in fetal outcome. Sepulveda et al. reported 10 cases of UVV and found 30% were associated with additional ultrasound (US) malformations, 20% with aneuploidy, and 40% with intrauterine fetal demise. In a review of published literature, Zalel et al. concluded that UVV was associated with a fetal mortality rate of 22.7%, aneuploidy in 11.4% of cases, and hydrops fetalis in 9% of cases. Rahemtullah et al. published a retrospective review of 25 cases of UVV; 35% of these fetuses had associated structural malformations, and 4% had chromosomal abnormalities. Fung et al. published a case series of 13 fetuses and included 80 additional cases previously reported in the literature. They reported a 31.9% rate of associated structural malformations, a 9.9% rate of aneuploidy, and a 13% perinatal loss rate. Normal outcomes were observed in 59.3% of cases. Intrauterine demise occurred between 29 weeks’ and 38 weeks’ gestation in 8.1% of fetuses with isolated UVV.

In the largest case series to date, Byers et al. identified 52 cases of UVV and recorded their outcomes. The authors found chromosomal abnormalities in 5.8% of fetuses; 28.8% had additional US abnormalities. No cases of intrauterine pregnancy loss were reported.

Manifestations of Disease

Clinical Presentation

UVV can be diagnosed during US examination at any time in pregnancy.

Imaging Technique and Findings

Ultrasound.

On US, UVV appears as a round or fusiform, anechoic structure, located either within the umbilical cord or within the fetal abdomen, inferior to the fetal liver and close to the anterior abdominal wall. Color flow, power Doppler, and pulsed wave Doppler US are useful to confirm the vascular nature of this lesion by showing venous flow in its lumen ( Figs. 103.1 and 103.2 , and ).