A procedure to drain bile to relieve pressure in the bile ducts caused by a blockage. An x-ray of the liver and bile ducts locates the blockage of bile flow. Images made by ultrasound guide placement of a stent (tube), which remains in the liver. Bile drains through the stent into the small intestine or into a collection bag outside the body. This procedure may relieve jaundice before surgery. Also called percutaneous transhepatic biliary drainage and PTCD.