Clinical images. Gallbladder torsion showing a "whirl sign" on a multidetector computed tomography scan.

An 82-year-old woman presented with a 5-day history of right upper quadrant pain. A physical examination showed a palpable tender mass in the right upper quadrant with Murphy's sign. The contrast-enhanced multidetector computed tomography (MDCT) scan clearly showed the twisted pedicle of the cystic duct and gallbladder mesentery on the right side of the gallbladder, thus showing a "whirl sign," and a definitive diagnosis of gallbladder torsion was made. The patient underwent a cholecystectomy, resulting in a favorable outcome. Therefore, the whirl sign on MDCT imaging can be a key to making a definitive diagnosis of gallbladder torsion.