Abernethy malformation

Last revised by Jeremy Jones on 26 Jul 2023

Abernethy malformations are rare vascular anomalies of the splanchnic venous system. They consist of congenital portosystemic shunts resulting from the embryonic vessels' persistence. 

Type I malformations are thought to occur only in females, while type II has a male predominance 1.

Two main types of Abernethy malformations have been described 6:

  • type I: end-to-side shunt; superior mesenteric and splenic vein drain separately into inferior vena cava

  • type II: side-to-side shunts; superior mesenteric vein and splenic vein form a common trunk before draining into the inferior vena cava

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:

  • type Ia: separate drainage of the superior mesenteric vein and splenic vein into systemic veins

  • type Ib: superior mesenteric vein and splenic vein join to form a short extra-hepatic portal vein which drains into a systemic vein (inferior vena cava, right atrium or iliac veins)

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.

Named after John Abernethy, who gave the first account of an absent portal vein with accompanying congenital mesentericocaval shunt 1,5 in 1793.

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Cases and figures

  • Case 1: CT
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  • Case 1: DSA
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  • Case 2: CT
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  • Case 3
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