Hepatobiliary and pancreatic: Commentary

Abstract

Journal of Gastroenterology and HepatologyVolume 17, Issue 2 p. 224-225 Free Access Hepatobiliary and pancreatic: Commentary First published: 23 November 2002 https://doi.org/10.1046/j.1440-1746.2002.t01-1-02715.xAboutSectionsPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat INTERPRETATION OF FIGURE 1 (SEE PAGE 216) Figure 1 is a computed tomography (CT) scan of the liver at a level near the hilum. The right and left hepatic lobes are continuous through a very thick portal vein. Both lobes are no longer continuous beyond the portal vein and are separated towards the anterolateral liver surface. The gap between the free edges of the right and left lobes contains a thick band of low density (arrow) which seems to be an extension of the very thick portal vein; the density of this band within the gap is lower than that of the liver parenchyma. It may be the partial volume phenomenon, or due to a low-density material like blood in a vessel. Please remember that on CT, the two lobes are sometimes totally separated, depending on the gross configuration of liver and CT cutting level. In lobar separation, the gap is usually void of tissue; sometimes, it contains a thin ligament, gallbladder or colon, but never a thick band structure like this. DIAGNOSIS: A LARGE PARA-UMBILICAL VEIN It is clear from her history, physical examination and laboratory data that she has liver cirrhosis due to chronic hepatitis C virus infection. Judging from the elevated NH3 level, flapping tremor, and her disoriented state, she seems to have hepatic encephalopathy. Encephalopathy results from functional failure of the liver and/or portal systemic collateral circulation. Although her liver function is severely compromised, portal systemic collateral circulation seems to be the dominant cause of encephalopathy in her case. The para-umbilical vein is one of the common routes of collateral circulation, occurring in one out of four patients with portal hypertension.1 In fact, bolus contrast enhancement CT clearly showed this density in question within the gap to be the para-umbilical vein (Fig. 2), which is continuous from the dilated portal vein. Figure 2Open in figure viewerPowerPoint Bolus enhancement computed tomography, portal phase. The original umbilical vein closes perinatally, and never reopens.2 The enlarged collateral vein that runs along where the embryonic umbilical vein was, is the para-umbilical vein, which is normally insignificant, but is frequently enlarged in portal hypertension for an ill-defined anatomical reason, and acts as a collateral vein. Figure 3 is a section of the abdomen at the level of the umbilicus (arrow). The opacified cross-sectioned collateral vein immediately beneath the umbilicus (right arrowhead) is an extension of the para-umbilical vein that courses caudad in the abdominal wall beneath the parietal peritoneum. The left arrowhead points at a section of a larger collateral vein, suggesting that several veins branch off the para-umbilical vein after it has left the liver. They seem to be coursing towards the pelvis. Such collaterals can cause varices within the pelvis, such as rectal varices.3 Figure 3Open in figure viewerPowerPoint Computed tomography at the level of the umbilicus. REFERENCES 1 Kimura K, Ohto M, Matsutani S et al. Relative frequencies of portosystemic pathways and renal shunt formation through the ‘posterior’ gastric vein: portographic study in 460 patients. Hepatology 1990; 12: 725 – 8. 2 Lafortune M, Constantin A, Breton G, Legare AG, Lavoie P. The recanalized umbilical vein in portal hypertension: a myth. AJR 1985; 144: 549 – 53. 3 Okuda K, Takayasu K. Aberrant varices. In: K Okuda, J-P Benhamou, ed. Portal Hypertension. Clinical and Physiological Aspects. Tokyo: Springer, 1991: 429 – 40. Volume17, Issue2February 2002Pages 224-225 FiguresReferencesRelatedInformation