Structural and functional biliary tree changes secondary to extrahepatic biliary obstruction.

To assess the potential structural changes of the biliary tree and the liver in patients with extrahepatic biliary obstruction, the resected specimens of 20 patients operated on for benign biliary stricture, were evaluated by means of immunocytochemical, histological and scanning electronmicroscopic studies. Furthermore, liver biopsies were taken for the same purposes. Our results showed that in the dilated segment of the hepatic duct proximal to the stricture, innervation was greatly reduced or completely absent with associated advanced morphological and histological changes and high intrabiliary pressure levels. Similar findings were observed in the liver biopsies, too. These biopsies showed advanced morphological and histological changes associated with reduced innervation. In contrast, the nondilated segment of the hepatic duct, distal to the obstruction, showed normal innervation, normal morphological and histological findings and normal levels of intrabiliary pressure. The present study provides evidence that in cases of extrahepatic biliary obstruction, there is a feature of advanced pathological changes in the biliary tree associated with alterations in innervation. These structural changes are associated with functional changes in both the liver and the biliary tree. These functional changes represent a threat to the patient, in particular if major surgery is required. Increased biliary pressure appears to be a major cause of the development of these changes. Biliary drainage, either surgical or endoscopic, is indicated as the sole alternative, to reduce the intrabiliary pressure and to contribute to a reversal of these structural and functional changes.