Fig. 1

a Abdominal ultrasonography. No gallstones or wall thickening are observed. Bile sludge is detected in the gallbladder. Contrast-enhanced abdominal tomography. The gallbladder is mildly enlarged; however, no wall thickening or gallstone formation is observed. b Surgical findings. The gallbladder is mildly enlarged; however, no thickening is observed, and there is little evidence of neovascularization and tissue fragility