Figure 3. Choledocholithiasis in a 20-year-old woman with elevated liver enzyme levels and right upper quadrant pain at 34 weeks gestation. US failed to demonstrate the distal common bile duct. Coronal thick-slab MR cholangiopancreatogram shows an obstructing stone in the common bile duct (arrow). The patient subsequently underwent endoscopic stone removal. Note the hydronephrosis of pregnancy involving the right kidney (arrowhead).