Gallbladder motility and cholesterol crystallization in bile from patientswith pigment and cholesterol gallstones

Background Little is known about gallbladder motility in patients with blac k pigment stones when compared to cholesterol gallstone patients, or about their relationship to biliary composition, crystallization and stone charac teristics. Design Fasting and postprandial gallbladder volumes were studied by ultraso nography in 49 gallstone patients with pigment (n = 14) or cholesterol (n = 35) stones and 30 healthy controls. After cholecystectomy stone compositio n, gallbladder wall inflammation, cholesterol saturation index and appearan ce of platelike cholesterol crystals in bile were evaluated in gallstone pa tients. Results Fasting gallbladder volume was significantly (P < 0.05) increased i n cholesterol stone patients (31.7 +/- 1.9 mL) but not in pigment stone pat ients (21.9 +/- 3.1 mL), compared to controls (21.0 +/- 1.5 mL). Postprandi al emptying was delayed in patients (half-emptying time: 31 +/- 2 min, 35 /- 3 min, 24 +/- 2 min in cholesterol stone patients, pigment stone patient s and controls, respectively, P < 0.05) and incomplete (residual volume: 43 .2 +/- 2.7%, 40.0 +/- 4.3%, 15.8 +/- 1.6% min in cholesterol stone patients , pigment stone patients and controls, respectively, P < 0.05). The inflamm ation of the gallbladder wall was mild or absent in all cases. Biliary chol esterol saturation index was 152.3 +/- 8.5% and 92.9 +/- 4.8% in patients w ith cholesterol and pigment stones, respectively (P < 0.01). Whereas choles terol crystals never appeared during 21 days in biles from patients with pi gment stones, crystal observation time in patients with cholesterol gallsto ne was 5 days (median) and was significantly shorter in patients with multi ple (4 days) than in patients with solitary (12 days) cholesterol stones (P = 0.0019). Conclusions Patients with black pigment stones who do not have excess chole sterol and do not grow cholesterol crystals in bile have decreased gallblad der emptying, although to a lesser extent than patients with cholesterol st ones. Thus, gallbladder stasis is likely to put a subset of subjects at ris k for the formation of pigment gallstones, and pathogenic mechanisms need t o be further investigated.