Abernethy malformation

Abernethy malformations are rare vascular anomalies of the splanchnic venous system. They comprise of congenital portosystemic shunts and result from persistence of the embryonic vessels. 

Type I malformations are thought only to occur in females with type II having a male predilection 1.


There are two main types of Abernethy malformations that have been described (initially devised by G Morgan and R Superina 6):

  • type I: end-to-end shunts
  • type II: side-to-side shunts

In type I shunts (end-to-end), there is a congenital absence of the portal vein with a complete diversion of portal blood into systemic veins (inferior vena cava, renal veins or iliac veins). These are further subdivided into those in which the splenic and superior mesenteric veins end up separately at the systemic veins, and those in which the splenic and superior mesenteric veins join to form a common trunk that ends up at the IVC, right atrium or iliac veins:

  • type Ia: separate drainage of the superior mesenteric and splenic veins into systemic veins
  • type Ib: superior mesenteric and splenic veins join to form a short extra-hepatic portal vein which drains into a systemic vein

In type II shunts (side-to-side), there is a hypoplastic portal vein with portal blood diversion into the inferior vena cava through a side-to-side, extrahepatic communication.


It was named after John Abernethy in 1793 who gave the first account of an absent portal vein and a congenital mesentericocaval shunt 1,5.  

Share article

Article Information

rID: 17836
Section: Pathology
Tag: cases
Synonyms or Alternate Spellings:
  • Abernethy's malformation
  • Abernethy malformations
  • Congenital absence of the portal vein
  • Congenitally absent portal vein

Support Radiopaedia and see fewer ads

Cases and Figures

  • Drag
    Case 1: CT
    Drag here to reorder.
  • Drag
    Case 1: DSA
    Drag here to reorder.
  • Drag
    Case 2: CT
    Drag here to reorder.
  • Updating… Please wait.

    Alert accept

    Error Unable to process the form. Check for errors and try again.

    Alert accept Thank you for updating your details.