Preparation of a contrast medium administration despite allergy | Contrast medium allergy

Preparation of a contrast medium administration despite allergy

For some indications, it is not possible to dispense with the administration of contrast medium even if the patient has an existing contrast medium allergy, because the best images are obtained with contrast medium. If contrast medium administration is necessary despite the allergy, the patient is given allergy-inhibiting medication prior to the examination. For pre-medication, a cortisone preparation is usually administered as a tablet twelve hours and two hours before the administration of contrast medium.

If oral administration is not possible, a drug can also be administered via the vein six hours before the examination. Directly before the examination, antagonists of histamine, a hormone responsible for allergic reactions, are also administered intravenously. Clemastine and ranitidine can be used for this purpose. If it is an emergency, it is not possible to wait for twelve hours before administering a cortisone preparation sufficiently before the examination. In this case, only the two antagonists of histamine are used directly before the administration of contrast medium.

What are the alternatives in case of contrast medium allergy?

Contrast media are used today in many different examinations, especially of course in imaging procedures. There, they are often necessary or at least significantly improve the result, as they make the body structures to be examined more visible. However, if a contrast medium allergy exists, there are two options for carrying out the examination in question: Firstly, certain examinations can also be performed without contrast medium, i.e. natively. However, if the administration of contrast medium is necessary, there is a second possibility: The person affected can then be given an infusion of a drug that blocks the receptors that cause the allergy. This drug will then remain effective until the examination is over and the contrast agent has been flushed out of the body.

Prophylaxis

The best prophylaxis is, of course, to avoid the contrast medium to which you have had an allergic reaction in the future. If you are allergic to one contrast medium, it does not immediately mean that you are allergic to all contrast media. Contrast media can be taken either intravenously or orally as drinking fluid.

When administered orally, an allergic reaction is not usually to be expected.However, oral contrast media are usually only used for contrast imaging of the gastrointestinal tract, so that the administration of an intravenous contrast medium (for imaging vessels) cannot be bypassed by oral administration. In order to avoid surprises for the examiner, an X-ray passport on which the corresponding contrast medium allergy is noted should be carried in any case. If an emergency occurs and you cannot be asked about an allergy before the examination, a severe allergic reaction can be avoided.

The contrast medium allergy should be mentioned to the treating physician before an imaging. As a rule, the doctor will always ask about any contrast agent allergy. However, contrast media are subject to strict controls during development, which are even stricter than with other drugs. Special care is taken to ensure that they have little or no allergic potential, so that contrast media are well tolerated in most cases.