Grey Turner's sign refers to bruising of the flanks, the part of the body between the last rib and the top of the hip. The bruising appears as a blue discoloration,[1] and is a sign of retroperitoneal hemorrhage, or bleeding behind the peritoneum, which is a lining of the abdominal cavity. Grey Turner's sign takes 24–48 hours to develop, and can predict a severe attack of acute pancreatitis.[2]