Abernethy malformations are an extremely rare anomalous group of the splanchnic venous system. They comprise of congenital portosystemic shunt and results from persistence of embryonic vessels.
Type I malformations are thought to only occur in females with type II having a male predilection 1.
There are two main types of Abernethy malformations 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.
- hepatic encephalopathy: from portosystemic shunting
- hepatic mass lesions
- hepatopulmonary syndrome 2
pulmonary arteriovenous fistulae
- thought to be due to hyperammonaemia
- may lead to systemic emboli
- other congenital abnormalities: particularly type I 1
History and etymology
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.
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- 6. Morgan G, Superina R. Congenital absence of the portal vein: two cases and a proposed classification system for portasystemic vascular anomalies. J. Pediatr. Surg. 1994;29 (9): 1239-41. J. Pediatr. Surg. (link) - Pubmed citation
- 7. Ringe K, Schirg E, Melter M et-al. [Congenital absence of the portal vein (CAPV). Two cases of Abernethy malformation type 1 and review of the literature]. Radiologe. 2008;48 (5): 493-502. doi:10.1007/s00117-007-1561-1 - Pubmed citation