T-tube cholangiography is an imaging technique used in order to check that there are no gallstones left in the bile duct following cholecystectomy (surgical removal of the gallbladders). A T-shaped rubber tube is inserted into the bile duct during the surgery and is left in place. After about a week, contrast medium is inserted into the tube and X-rays are taken. If there are no stones, the tube is pulled out. If there are, they may be removed by ERCP (endoscopic retrograde cholangio-pancreatography) or by a stone-dissolving solvent administered through the tube.