Aneurysms of the portal venous system

Aneurysms of the portal vein are extremely rare and represent only 3% of all aneurysms of the venous system ¹.

Clinical presentation

Most patients are asymptomatic but may present with nonspecific abdominal pain as a major symptom ^2-4.

Pathology

Both congenital and acquired causes have been proposed. Acquired causes may include ^2-3:

• portal hypertension: could be contributory but is not essential to the development of portal venous system aneurysms and majority of patients do not have portal hypertension or chronic liver disease.
• necrotising pancreatitis
• abdominal trauma or surgery
• liver cirrhosis

Location

The most common locations for aneurysms of the portal venous system are ^2-3:

• splenomesenteric venous confluence
• main portal vein
• intrahepatic portal vein branches at bifurcation sites

And the rarest locations are splenic, mesenteric, and umbilical veins.

Radiographic features

Diagnosis can be made when the portal vein exceeds 20mm in diameter.

Ultrasonography

Colour Doppler ultrasound is the most helpful diagnostic tool. Further work-up may not be necessary ⁴. Appearing on ultrasound as anechoic masses showing direct luminal continuity with the portal venous system and displayed spectral findings characteristic of the portal venous system on colour Doppler ultrasound ^5-6. 

CT

Dynamic helical CT demonstrated simultaneous enhancement with the portal system ^5-6.

MRI

On MR images aneurysms were hypointense owing to flow void on T1-weighted ⁵.

Complications

Complications include ^2-4:

• thrombosis and distal embolism
• portal hypertension
• rupture
• compression of the duodenum
• compression of the common bile duct causing jaundice, cholestasis, and cholelithiasis