Carbon dioxide is useful as a contrast agent for diagnostic imaging and the treatment of malignant biliary obstruction in patients who are allergic to iodine-based contrast agents

Diagnosis and treatment of biliary tract disease require an intraductal radiocontrast agent. However, some patients show severe allergic reactions to commonly-used iodinated contrast agents. Here, we used carbon dioxide (C02) as an alternative radiocontrast agent in patients who are allergic to iodine-based contrast medium in the diagnosis and treatment of malignant biliary obstruction caused by cancer of the head of the pancreas. We were able to obtain a good cholangiogram and perform placement of a metal stent by using CO2 cholangiography. Therefore, CO2 cholangiography is a good alternative to iodine-based cholangiography in patients who are allergic to iodine.