Type II Abernethy Malformation

Nicholas Kolanko

Northwestern McGaw Hospital

n-kolanko@md.northwestern.edu

Cynthia Rigsby, MD

Abstract

3 month old male presents with jaundice.

Keywords

1518 portocaval shunt, jaundice, hyperbilirubinemia, vascular malformation, viscera, congenital absence of the portal vein, congenital extrahepatic portosystemic shunt, TIPS


Publication Date: 2009-04-23

History

3 month old male presents with jaundice.

Findings

There is a large portosystemic shunt connecting the intrahepatic portal vein with the inferior vena cava.

The right hepatic vein connects with the infrahepatic IVC.

The left hepatic lobe is enlarged.

Aberrant vessel in the right hepatic lobe connecting to the IVC through capsular veins.

Diagnosis

Abernethy Malformation (Type II)

DDx

Type II Abernethy shunt; Type I Abernethy shunt

Discussion

Abernethy malformation, also known as congenital extrahepatic portosystemic shunt, is a rare abnormality of the splanchnic venous system whereby blood from the mesentery and spleen bypass the liver through an anomalous shunt via the portal vein (or equivalent) and the IVC.

Understanding of how this malformation occurs is aided by a review of splanchnic vascular embryology:

Portal vein: The portal venous system develops through modulations (anastomoses and obliterations) of the extra-embryonic vitelline and umbilical veins, whereas the systemic venous systems develops from the anterior and posterior cardinal veins, which are intra-embryonic vessels. The vitelline veins are paired structures which ascend in the abdomen towards the liver (right and left; initially there are three horizontal interconnections, but ultimately only one interconnection persists as part of the final portal vein.

Systemic veins (IVC): The IVC is produced when a portion of the sinus venosus and a portion of an anastomosis between the right and left vitelline veins join in the liver.

In summary, the close interaction of the precursors to the portal vein and IVC enable abberant vasculature.

In type I Abernethy malformation, there is complete absence of the portal vein, with resultant redirection of splanchnic blood directly and completely into the IVC. This is usually associated with other congenital anomalies such as polysplenia, biliary atresia, interrupted IVC, intestinal malrotation, hepatic tumors and cardiac defects. However, hepatic synthetic and other functions are generally well-preserved. It is seen exclusively in females. Type I can come in two varieties: A: nonunion of the splenic vein and SMV, and B: union of the splenic vein and SMV.

In type II Abernethy malformation (A: congenital; B: acquired), there is a side-to-side connection between the extra-hepatic portal vein and IVC, with a partially formed IVC. So, the portal vein is partially preserved. Patients with this subtype are generally males who present later in life with hepatic dysfunction and encephalopathy.

The definitive treatment for type I malfomations consists of liver transplanation, whereas type II malformations can be treated with surgical closure of the shunt.

References

  1. Davenport M. Howard E. Congenital extrahepatic portocaval shunts—The Abernethy Malformation Journal of Pediatric Surgery, Volume 32, Issue 3, March 1997, Pages 494-497
  2. Berquist W. Sze D. SIR 2008 Annual Meeting Film Panel Case: Abernethy Malformation. Volume 19, Issue 9, Pages 1274-1277 (September 2008)

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