Choledocholithiasis is the condition in which a gallstone has migrated from the gallbladder into the common bile duct, where it can obstruct the flow of bile. Symptoms include upper abdominal pain, jaundice, and fever, and blockage risks serious infection of the bile ducts or inflammation of the pancreas. Diagnosis uses ultrasound, MRCP, or endoscopic imaging, and treatment typically involves endoscopic removal of the stone, sometimes followed by gallbladder surgery to prevent recurrence. Dietary advice during episodes is low-fat and light until the obstruction is cleared, since fat stimulates the gallbladder contraction that drives stones onward.