A case of torsion of the gallbladder is presented. This is a rare condition that occurs when it is associated with anatomical variants related to abnormal fixation of the gallbladder to the liver bed. The blood irrigation is insufficient and the gallbladder develops necrosis. The abnormal implantation occurs in 4 per cents of the population. If the gallbladder losses its fixations to the inferior margin of the liver with the presence of a long mesocyst a torsion can occur when this gallbladder twists axially with subsequent occlusion of the blood flow.

The signs and symptoms are similar to those of severe acute cholecystitis:

abrupt onset of the pain and large palpable mass below the right costal margin. The ultrasound can show a very large and anteriorly floating gallbladder. In this case, the ultrasound did not show any abnormal signs, so it is usually diagnosed at laparotomy and the treatment consists of cholecystectomy. This condition should be suspected in acute abdominal pain of unknown origin