Morphological appearance of low-level echoes in the gallbladder. Interpretation with microscopic biliary analysis and clinical correlation.

A total of 743 patients affected by various gastrointestinal disorders were examined by ultrasound. The presence in the gallbladder bile of low-level echoes (LLE) was observed in 56 (7.5%). Twenty-six of these patients had surgery: 24 underwent cholecystectomy for important biliary-like painful symptomatology, and 2 had cephalopancreatectomy for pancreatic head carcinoma. Both macro- and microscopic controls of the bile were carried out in all 26 patients. In 20 cases, only microscopic cholesterol crystals and calcium bilirubinate granules were observed in the bile. The microscopic evidence of these crystals was associated in four cases with macroscopic evidence of so-called "biliary sludge" and in four cases with macroscopic evidence of highly viscous bile. In the other 6 cases these crystals were associated with the presence of cholesterol stones. The authors consider that the observation of LLE in the gallbladder bile is an important index of the presence of cholesterol crystals and/or calcium bilirubinate granules. These LLE can assume polymorphic aspects, described by the authors, which may simulate other pathologies and lead to incorrect echographic diagnosis. The high incidence of LLE in an alithiasic population (5.1%), together with the elevated frequency, according to the authors, of association of these echoes with a painful biliary-like symptomatology (52.6%), underlines the diagnostic importance of an accurate ultrasound investigation in this type of pathology.