* Ultrasound Division, ASL Roma B, Rome, Italy
** Ultrasound Division, Ceprano Hospital, Ceprano, Italy.
Introduction
Aneurysm and varix are both focal dilatations of the umbilical vessels affecting the umbilical artery or vein respectively.
Varix of the umbilical vein is an uncommon anomaly, representing only 4% of umbilical cord malformations (1). There are two following types of umbilical vein varices:
1) Intra-abdominal portion of the umbilical vein and / or umbilical portion of the left portal vein (i.e. intrahepatic or intra-abdominal extrahepatic). It involves more frequently the intraabdominal extrahepatic portion of the umbilical vein because this is part of the vessel with the least support.
2) Intra-amniotic portion of the umbilical vein. This type has rarely been reported (2).
DiagnosisA varix of the intra-abdominal part of the umbilical vein is recognized as a cystic round or fusiform shaped mass oriented obliquely in the caudo-cranial direction and located within the liver (intrahepatic type) or between the abdominal wall and the inferior edge of the liver (extrahepatic type) (3).
Rarely, it may show as a large mass. Color Doppler and color flow imaging is valuable tool in the prenatal diagnosis. It demonstrates continuous or turbulent flow within the mass. Color flow imaging and its continuity with the umbilical vein, allows a definite diagnosis of the umbilical vein varix (4) and differentiation from other abdominal cystic masses.
Mahony et al. showed that the diameter of the normal intra-abdominal umbilical vein increases linearly with the gestational age. It ranges from 3 mm at 15 weeks gestation to 8 mm at term (R = 0.92) (3).
Diagnostic criteria of umbilical vein varix include:
- umbilical vein diameter greater than 9 mm
- or minimum 50% enlargement in the varix diameter than the diameter of the intrahepatic umbilical vein (5).
Differential diagnosis
Choledochal, liver, mesenteric, ovarian or urachal cyst, cystic lymphangioma.
Conclusions
Regarding the clinical significance of the umbilical vein varix, literature reports controversial data: favorable outcome (2,6,7) and high incidence of fetal anomalies (8) and/or obstetric complications mostly due to thrombosis of the varix (3,9).
Although data are discordant, a meticulous study of the fetal morphology and serial sonographic evaluation of the fetus, with particular attention to the blood flow within the varix, should be carried out.
Case report 1
This is a case of a 33-year-old patient in her second pregnancy (G2 P1). Her previous pregnancy, 10 years ago, was uneventful and she delivered healthy baby, neonatal weight of 4500 grams. Patient and her husband, father of the baby, were both tall, she measured 178 cm and him 190 cm.
Her current pregnancy was uncomplicated and previous ultrasound examinations performed at different center were reported as normal.
At 33 weeks of gestation, her amniotic fluid index (AFI) was 30 cm and an estimated fetal weight was 3000 grams (abundantly above the 95° percentile) with proportional fetal growth. There was no sign of visceromegaly.
We saw an ovoid structure at the level of the urinary bladder. The structure showed continuity with the intraabdominal part of the umbilical vein that resulted to be of a normal diameter at the hepatic level. The largest diameter measured 13 mm. The Doppler showed continuous flow. Our diagnosis was intraabdominal extrahepatic umbilical vein varix.
Patient delivered spontaneously at 38 weeks. A healthy female of 4300 grams, neonatal length of 55 cm, Apgar scores of 9/10 at 1st/5th min respectively, was born. Both were dismissed in very good conditions 3 days after delivery.
Images 1,2: Images show an anechogenic lesion, umbilical vein varix, in front of the urinary bladder measuring 13 mm in diameter.