A history of allergy to radiocontrast media is a common problem. A careful history is the key to diagnosis and premedication can reduce but not eliminate the risk of a second reaction.
Iodinated radiocontrast media are the most commonly used type of contrast agent and are frequently used for improving image quality and definition in radiological tests such as CT scans, as well as in interventional procedures such as in cardiac catheterisation and endoluminal arterial stenting. Patients may have a reaction while having any one of these procedures, and the question then arises regarding the safety of re-exposure to contrast agents during a repeat of the same procedure or during another procedure involving contrast media.
This article discusses hypersensitivity reactions to contrast media and how to manage patients who present with a history of this. Adverse reactions that are not immunologically based, such as contrast nephropathy and contrast extravasation, are not discussed. A case study is provided in the box on page 73.