Biliary changes in extrahepatic portal venous obstruction: compression by collaterals or ischemic?

Background: The postulated mechanisms of biliary abnormalities in extrahepa tic portal venous obstruction (EHPVO) are either extrinsic compression by c ollaterals or ischemic injury due to venous thrombosis. If the former hypot hesis is correct, then biliary changes should revert to normal after portas ystemic shunt surgery. Methods: Five patients with EHPVO who underwent portasystemic shunt surgery were studied. One of these patients had obstructive jaundice due to portal cavernoma. Endoscopic retrograde cholangiography (ERC) was performed befor e as well as after the shunt surgery. Doppler ultrasound and splenoportoven ography were obtained to confirm the diagnosis of EHPVO as well as shunt pa tency. Results: All patients had biliary abnormalities on pre-shunt ERC. The post- shunt ERC showed partial reversal of biliary abnormalities in 3 patients, c omplete reversal in 1 patient, and no reversal in 1 patient. Smooth strictu res opened after shunt surgery and proximal dilatation disappeared in most patients. The indentations and caliber irregularities disappeared after shu nt surgery, whereas angulations and ectasias of biliary ducts persisted. Conclusion: Shunt surgery results in regression of some of the biliary abno rmalities and relieves biliary obstruction, suggesting that mechanical comp ression by collaterals is the mechanism behind biliary abnormalities in EHP VO. However, some biliary changes persist after shunt surgery signifying fi xed obstruction due to ischemia or fibrous scarring. Thus, the two theories are not mutually exclusive.