Umbilical vein varix

Umbilical vein varix (UVV) refers to a focal dilatation of the umbilical vein.

Epidemiology

Associations

UVVs were initially thought to have a high association with other anomalies which include:

• chromosomal anomalies: 5-12% with FIUVV ^2,3
  • Down syndrome  
• underlying congenital cardiovascular anomaly

Recent literature points to more favorable outcomes when FIUVV is an isolated finding, with significantly lower associations with aneuploidy and mortality than initially reported ^14,15.

Pathology

Location

It tends to favor the intra-abdominal portion of the cord (typically between the abdominal wall and the liver) which is then termed a fetal intra-abdominal umbilical vein varix (FIUVV) or the intra-amniotic portion of the umbilical vein.

Radiographic features

Ultrasound

Using antenatal ultrasound, an intra-abdominal UVV may be seen as a cyst-like structure in the fetal upper abdomen with venous flow within on color Doppler interrogation. The term umbilical varix is defined when the caliber is greater than 9 mm or with a ratio of more than 50% between the dilated and a more distal normal intra-abdominal portion of the vein.

Treatment and prognosis

The overall clinical course is variable and unpredictable ranging from favorable in some to unfavorable in others ⁶. Most cases with an isolated varix have a very good prognosis; most neonates will have a normal outcome.

Complications

• development of hydrops fetalis: ~5% ¹²
  • due to thrombosis
  • possibly from an associated cardiovascular anomaly 

Differential diagnosis

• urachal cyst
• ovarian cyst
• choledochal cyst
• cystic lymphangioma
• enteric duplication cyst

Practical points

Due to its association with other fetal anomalies and relatively high mortality rates (when not an isolated finding), a careful fetal search for other abnormalities as well as close monitoring is recommended if detected prenatally. Follow-up is warranted when an umbilical vein varix is diagnosed (growth and well being), more so if other abnormalities are identified ^1,7. 

See also

• umbilical arterial aneurysm (UAA)
• umbilical venous dilatation