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.
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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; indeed, the majority of patients do not have portal hypertension or chronic liver disease
- necrotizing 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
The rarest locations are the splenic, mesenteric, and umbilical veins.
Radiographic features
Diagnosis can be made when the portal vein exceeds 20 mm in diameter.
Ultrasound
Color Doppler ultrasound is the most helpful diagnostic tool. Further workup may not be necessary 4. An aneurysm appears on ultrasound as an anechoic mass showing direct luminal continuity with the portal venous system and displays spectral findings characteristic of the portal venous system on color Doppler interrogation 5-6.
CT
Dynamic helical CT demonstrates simultaneous enhancement with the portal system 5-6.
MRI
In T1-weighted images, aneurysms are hypointense owing to the flow void phenomenon 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