Cavernous Transformation and Portal Vein Obstruction
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- Cavernous transformation: the collection of collaterals that develop around an obstructed vessel
- Portal vein obstruction
- Can occur anywhere along the course of the main portal vein or splenic vein, between the hilum of the spleen and the porta hepatis
- In pediatrics, obstruction is most typically of the portal vein.
- Major cause of prehepatic portal hypertension
- Most children with portal vein thrombosis present between birth and 15 years of age.
- Acute presentation is rare.
- Chronic cases present with complications of portal hypertension.
- Gastrointestinal (GI) bleeding is more typical in patients presenting <7 years of age.
- Splenomegaly in the absence of symptoms is more typical for patients aged 5–15 years.
A genetic basis of this problem has not been identified, although congenital abnormalities of the heart, major blood vessels, biliary tree, and renal system are often found.
- In cirrhosis and hepatic malignancies, the thrombus usually begins intrahepatically and spreads to the extrahepatic portal vein.
- In most other etiologies, the thrombus usually starts at the site of origin of the portal vein.
- Occasionally, thrombosis of the splenic vein propagates to the portal vein, most often resulting from an adjacent inflammatory process (e.g., severe pancreatitis).
- Asymptomatic splenomegaly or upper GI hemorrhage results from extrahepatic portal hypertension.
- Less commonly, ascites or failure to thrive, and portopulmonary hypertension
50% of portal vein obstructions are idiopathic. Identified causes include the following:
- Congenital vascular anomaly
- Portal vein malformation
- Webs or diaphragms within the portal vein
- Clot resulting from a hypercoagulable state
- Clot from other causes:
- Umbilical vein catheterization
- Portal pyelophlebitis
- Intra-abdominal sepsis
- Surgery near the porta hepatis
- Other causes for portal vein obstruction in older children:
- Ascending pyelophlebitis from perforated appendicitis
- Primary peritonitis, cholangitis, and pancreatitis causing a splenic vein thrombosis
- Inflammatory bowel disease