Mechanisms of adverse reactions to iodinated contrast material

In the light of present knowledge, the mechanisms of accidents encountered with water-soluble iodinated contrast media are reviewed. Even today, the death rate, estimated at one for between 20,000 and 40,000 examinations, remains impressive. Two main topics are discussed: 1) Those accidents related to the hyperosmolality of the products. 2) Those accidents related to the activation of the various biological systems, or anaphylactoid reactions. Progress made as concerns the knowledge of the physiopathological mechanisms provides hope for better prevention of these accidents. Iodine testing, as it is presently conceived, has been shown to be ineffective and has been forsaken.