Cavernous Transformation and Portal Vein Obstruction

Cavernous Transformation and Portal Vein Obstruction is a topic covered in the 5-Minute Pediatric Consult.

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Basics

Description

  • Cavernous transformation
    • Is a term used to describe the collection of collaterals that develop around an obstructed vessel
    • Often develops with obstruction of the portal vein
  • 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 or noncirrhotic portal hypertension

Epidemiology

  • 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 to 15 years.

Risk Factors

Genetics

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.

Pathophysiology

  • 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 along 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 can occur, as well as portopulmonary hypertension

Etiology

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:
    • Omphalitis
    • Umbilical vein catheterization
    • Portal pyelophlebitis
    • Intra-abdominal sepsis
    • Surgery near the porta hepatis
    • Sepsis
    • Cholangitis
    • Dehydration
    • Trauma
  • 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

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