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

The postulated mechanisms of biliary abnormalities in extrahepatic portal venous obstruction (EHPVO) are either extrinsic compression by collaterals or ischemic injury due to venous thrombosis. If the former hypothesis is correct, then biliary changes should revert to normal after portasystemic shunt surgery.

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 before as well as after the shunt surgery. Doppler ultrasound and splenoportovenography were obtained to confirm the diagnosis of EHPVO as well as shunt patency.

All patients had biliary abnormalities on pre-shunt ERC. The post-shunt ERC showed partial reversal of biliary abnormalities in 3 patients, complete reversal in 1 patient, and no reversal in 1 patient. Smooth strictures opened after shunt surgery and proximal dilatation disappeared in most patients. The indentations and caliber irregularities disappeared after shunt surgery, whereas angulations and ectasias of biliary ducts persisted.

Shunt surgery results in regression of some of the biliary abnormalities and relieves biliary obstruction, suggesting that mechanical compression by collaterals is the mechanism behind biliary abnormalities in EHPVO. However, some biliary changes persist after shunt surgery signifying fixed obstruction due to ischemia or fibrous scarring. Thus, the two theories are not mutually exclusive.