Portal vein stenosis

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  Elevated portal vein velocity > 125 cm/s at anastomosis

  
  
  
  
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    Portal vein velocity normally < 60 cm/s

  
  
  
  
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  Anastomotic:preanastomotic velocity ratio

  
  
  
  
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    Stenosis: > 3.0

    
    
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    Normal: ~ 1.5

  
  

Portal vein thrombosis

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  No detectable flow in portal vein

  
  
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  May see echogenic thrombus in portal vein, or portal vein may appear markedly hypoechoic or even anechoic

  
  
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  May see enlarged hepatic arteries

  
  
  
  
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    Hepatic arteries compensate for portal vein thrombosis due to hepatic arterial buffer response

  
  
  
  
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  Bidirectional low-amplitude flow in portal vein may precede portal vein thrombosis

Portal vein stenosis

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  Occurs at site of anastomosis

Portal vein thrombosis

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  Associated with surgical technique

  
  
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  Hypercoagulable state

Portal vein stenosis typically occurs at anastomosis

Depending on degree of stenosis, may require balloon angioplasty

Portal vein stenosis and thrombosis are relatively rare, occurring in 1-2.7% of liver transplants

In chronic or longstanding portal vein stenosis, may see portal vein aneurysm downstream from anastomosis and helical flow in dilated portion of portal vein