Final answer:
Transhepatic cholangiography is an imaging procedure used to visualize the bile ducts. Allergies to contrast agents should be checked before the procedure.
Step-by-step explanation:
Transhepatic cholangiography is an imaging procedure used to visualize the bile ducts. It involves injecting a contrast agent into the liver and obtaining X-ray images to evaluate the biliary system. Before the procedure, it is important to check for any allergies to contrast agents, as these substances are used to make the bile ducts visible on the X-ray images.