Patent paraumbilical vein(s) in portal hypertension
It is not uncommon to encounter patent paraumbilical veins when scanning a patient with liver cirrhosis. Usually noticed when you are imaging the portal vein as a part of venous congestion (#VExUS) assessment.
In adults, the umbilical vein is completely occluded, mainly in its distal part, forming a fibrous structure – round ligament. The paraumbilical veins are found around the falciform ligament next to the round ligament. They are composed of Burow’s veins and Sappey’s inferior and superior veins. In healthy individuals, these veins are collapsed, but not completely occluded. See the following images to recollect the anatomy of the mentioned ligaments.
The paraumbilical veins connect the left branch of the portal vein with veins of the ventral abdominal wall in the umbilical region. In portal hypertension, these paraumbilical veins work as a conduit between the portal circulation and systemic circulation. While ‘recanalized umbilical vein’ is commonly found in radiology reports, apparently, it is the enlarged paraumbilical vein(s) they are describing. An old study that included 200 patients with portal hypertension (surgical descriptions and autopsies) did not find any reopened or recanalized umbilical veins.
Here are a few slides on Porto-systemic connections from the stated reference. A must-read article.
Now let us see POCUS examples. If there is a red vessel on color Doppler going out of the liver from the left portal vein (hepatofugal flow; towards the probe) in a patient with cirrhosis, that is what is the paraumbilical vein. It can often be traced till umbilicus unless there is interfering bowel gas.Interestingly, hepatopetal flow (systemic to portal shunting) may be seen in cases of IVC thrombosis.