Case Study: Diagnosis of Umbilical Vein Varix

At 28 weeks’ gestation, a 32-year old woman underwent routine obstetrical ultrasonography. She had normal menstrual cycles prior to the pregnancy and had no history of any major illnesses prior to or during the current pregnancy. This was her third pregnancy.

Present pregnancy: The patient had amenorrhea for 28 weeks, which corresponds with the age of the fetus on ultrasound scan. She has had no history of discharge or bleeding per the vagina during this pregnancy.

Clinical examination: Blood pressure was normal at 120/82 mm Hg; her other vital signs were within normal limits. Chest examination also was unremarkable. On abdominal examination, the fundal height of the patient matched the gestational age of 28 weeks.

Imaging studies: This patient underwent routine transabdominal ultrasonography to exclude any congenital fetal anomalies. An ultrasound scan in the first trimester yielded normal findings. The ultrasound images of the current examination are shown here.

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What are your findings based on Figures 1 and 2?

Ultrasound Findings

Figure 1 shows a transverse section of the fetal abdomen, and you may have noticed an abnormality. The fetal abdomen appears normal in size and shape, with the urinary bladder visualized in the normal position in the fetal pelvis. There is evidence of an anechoic lesion just above the fetal bladder. What is its relation to the fetal urinary bladder? Is it part of the bladder? Is it arising from the fetal bladder? Is it part of the fetal pelvis or arising from the pelvis?

This cystic lesion may arise from the bladder, which makes bladder diverticulum a possible diagnosis. However, this is not a common lesion in fetuses. The second possibility is an urachal cyst, which is a known fetal anomaly, making the likelihood of such a diagnosis very high. However, what does Figure 2, a color Doppler study, show?

On careful observation, the lesion appears to be in the midline with visible internal flow signals. The flow within the lesion appears turbulent when looking at the color signals. Since an urachal cyst does not show vascularity or flow signals, Figure 2 rules out this diagnosis. There are no other lesions or malformations of the fetus visible in Figures 1 and 2. However, a closer look at Figure 2 reveals that the structure that appeared to be a cystic lesion in Figure 1 seems to be connected to a vessel that leads superiorly towards the fetal liver. Is there any relation to the first finding, or is it another incidental finding?

Another diagnostic possibility is a choledochal lesion, arising from the biliary tree, or a choledochal cyst. Also, we must consider ovarian cysts and mesenteric cysts. However, the flow signals within the cystic lesion visible in Figure 2 would exclude these diagnoses.

Here’s what we know: The lesion is anechoic and vascular and appears connected to a vessel leading to the liver. The fetal umbilical vein fits this criterion, and it could be an aneurismal enlargement of the fetal umbilical vein. In addition, this diagnosis can explain all of the previously mentioned findings:

1. A small, anechoic lesion in the fetal abdomen in close proximity to the fetal urinary bladder.

2. No significant mass effects due to the lesion on adjacent structures.

3. Presence of color flow signals within the cystic lesion.

4. Continuity of the cystic lesion with the umbilical vein.

More images may help confirm the diagnosis.

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Figure 3 shows that the lesion measures 2.4 cm in diameter. Figure 4 shows a venous flow pattern with turbulence within the cystic mass. These findings show an aneurismal dilatation of the umbilical vein, which is called an umbilical vein varix. This is a focal variceal dilatation of the umbilical vein. A diameter of more than 9 mm is considered diagnostic of an umbilical vein varix. This lesion measures 24 mm and seems to meet fully all diagnostic criteria for an umbilical vein varix.

Final diagnosis:Intra-abdominal umbilical vein varix

Discussion

An umbilical vein varix is a focal dilatation of the umbilical vein in its intra-abdominal or intra-amniotic sections. Umbilical vein varix represents only about 4% of all umbilical cord anomalies. It is significant because certain studies show that this diagnosis is associated with increased incidence of fetal anomalies and increased rates of fetal morbidity and mortality. However, additional study is essential to prove this association conclusively.

This case study involves an intra-abdominal extrahepatic umbilical vein varix. This is the most common location of this cord anomaly. It is extremely rare to detect an intra-amniotic umbilical vein varix. One of the criteria for diagnosis of varix is that the diameter of the umbilical vein should be greater than 9 mm. Another criterion is that the umbilical vein diameter at the site of the varix must measure 50% more than the diameter of the intrahepatic portion of the umbilical vein. On color Doppler study, there is evidence of significant flow within the cystic lesion. Spectral Doppler of the lesion shows typical venous flow pattern or even turbulent flow, as in this case.

Differential Diagnoses

The main differential diagnosis for intra-abdominal umbilical vein varix is cystic lesions of the fetal abdomen. These would include mesenteric cyst, urachal cyst, ovarian cysts, as well as choledochal cysts and cystic lymphangioma. The presence of turbulent venous flow clearly favors a diagnosis of umbilical cord varix and rules out the previously mentioned cystic lesions.

Prognosis

In the absence of other associated anomalies, such as in this case, the only danger is of thrombosis of the umbilical vein varix with all its associated complications and morbidity. Usually, a careful follow-up ultrasound examination is sufficient to rule out this condition.

References:

Antony J. Ultrasound image gallery website. Available at: http://www.ultrasound-images.com. Accessed May 2, 2014.

Goubaa M. Umbilical vein varix. Available at: http://sonoworld.com/fetus/page.aspx?id=2193. Accessed May 2, 2014.

Rumack CM, Wilson SR, Charboneau JW, Levine D, eds. Diagnostic Ultrasound. 4^th ed. Philadelphia: Mosby; 2011.

Vignal P. Intra-abdominal umbilical vein varix. Available at: http://sonoworld.com/fetus/page.aspx?id=187. Accessed May 2, 2014.