Original Title: Prévention d’une réaction d’hypersensibilité aux agents de contraste administrés par voie intravasculaire lors d’un examen d’imagerie médicale chez l’adulte

Authors' objectives: For people who have already experienced a hypersensitivity reaction to a contrast agent, various preventive measures can be considered to prevent the occurrence of a new reaction. These include prophylaxis with corticosteroids and/or antihistamines for those deemed to be at risk. However, the relevance of this measure is controversial, and the recommendations of the various learned societies on this subject are heterogeneous. In this context, the Association des médecins d'urgence du Québec has asked the Institut national d'excellence en santé et en services sociaux (INESSS) to draw up recommendations for best clinical practice in preventing hypersensitivity reactions to intravascular contrast media.

Authors' results and conclusions: RESULTS (#1 PREVENTIVE MEASURES): Preventive measures should only be considered for people with a previous hypersensitivity reaction to a contrast agent, since this is the main risk factor for the occurrence of a new reaction. The different prevention strategies depend essentially on the severity of the previous reaction, the identification of the culprit contrast agent, and the urgency of the examination. (#2 CHANGE OF CONTRAST AGENT): In the case of a medical imaging examination requiring an iodine- or gadolinium-based agent in a person who has had a mild or moderate hypersensitivity reaction in the past, a change of contrast agent is the main preventive measure, as it can help reduce the likelihood of a new reaction. More precisely, this involves administering another molecule of the same type of agent (depending on the medical imaging test), but which is less likely to provoke a new reaction due to differences in its molecular structure. In the case of a history of severe hypersensitivity reactions, a change of contrast agent may also be considered if the use of such an agent is deemed essential to the examination. To use this measure, it is necessary to identify the name of the agent (molecule) that caused the previous reaction. If the culprit agent cannot be identified, the contrast agent normally used for this examination should be administered if the previous reaction was mild, bearing in mind that the severity of a new reaction would possibly also be mild, or more exceptionally moderate. In the case of a history of moderate severity, it is necessary to take the time to investigate the agent involved if the examination is nonurgent, or to try to use a contrast agent that is less likely to have been used during the initial reaction (depending on the agent usually used by the centre where the previous examination took place). (#3 PERFORMING ANOTHER TYPE OF IMAGING): For people with a history of moderate to severe hypersensitivity to iodinated or gadolinium-based contrast agents, in addition to considering a change of contrast agent, the use of another type of imaging should also be considered if possible, as well as consultation with an allergist if there is no urgent need to perform the examination. Before using a contrast medium in these patients, it is essential to assess on a case-by-case basis whether the benefits of the examination outweigh the risks of provoking a new reaction of this type. (#4 WITHDRAWAL OF PROPHYLAXIS): Administration of a first-generation antihistamine may prevent the occurrence of a subsequent hypersensitivity reaction, compared with no prophylaxis, when a non-ionic iodinated agent is administered (low to moderate level of evidence). Administration of an antihistamine alone for prophylaxis, however, is associated with little clinical benefit, since a hypersensitivity reaction may still occur. At best, antihistamines may alleviate some skin symptoms. (#5 DOCUMENTING HYPERSENSITIVITY REACTIONS): In the event of a hypersensitivity reaction, it is essential to accurately document the reaction in the patient's radiological and electronic records, in order to optimize management during subsequent tests. This includes the name of the contrast agent administered and a full description of the reaction. (#6 ASSESSMENT IN ALLERGOLOGYE): A consultation with an allergist should be considered in certain clinical situations, such as the occurrence of a severe reaction, the occurrence of a moderate reaction dating back less than 5 years and involving respiratory or cardiovascular involvement, or when the patient has had reactions to several contrast agents. The allergist will be able to determine the allergic nature of the hypersensitivity reaction and suggest alternative contrast agents. A tryptase test in the acute phase of an immediate and severe reaction IX should also be considered to accompany the allergology request. Finally, an evaluation of a reaction to a sound agent may be relevant, given that it may be a reaction to the polyethylene glycol contained in such agent. (#7 ENVIRONMENTAL CONSIDERATIONS): Contrast media contaminate not only wastewater, but also drinking water, as they are partially resistant to treatment processes in wastewater treatment plants. Their accumulation poses a risk to the environment and human health. The judicious use of contrast media could contribute to the protection of the environment and the sustainable management of resources.

Authors' recommendations: Following an iterative process with the members of the advisory committee, in which scientific data, information and recommendations drawn from the literature, contextual elements and the perspective of the various stakeholders consulted were triangulated, a number of findings and recommendations were formulated. These, which are at the heart of the report, are also integrated into a decision-support tool aimed mainly at primary healthcare professionals.

Authors' methods: In order to address this mandate, a systematic review of documents was carried out in bibliographic databases and other information sources to identify documents presenting information or clinical recommendations on the prevention of a hypersensitivity reaction to contrast agents, with a view to document the modalities of good clinical practice as well as the population dimension. In addition, a systematic literature review of primary studies on the efficacy of prophylaxis for the prevention of hypersensitivity reactions to contrast media during medical imaging examinations in adults was conducted. A manual search of the literature was also carried out, consulting, among others, the websites of learned societies specializing in the field, as well as regulatory or health technology assessment agencies. A narrative review was conducted to document environmental considerations. Contextual information on professional and organizational issues was also sought, notably on the supply and diversification of contrast agents specific to Québec.

Authors' identified further research: The relevance of updating the recommendations will be assessed four years from the date of publication of this work, depending on the progress of scientific data and the evolution of clinical practices, or on the needs of the health and social services network. If necessary, the stakeholders who accompanied the work may be consulted to check whether they consider it appropriate to update the documents.

Project Status: Completed

URL for project: https://www.inesss.qc.ca/publications/repertoire-des-publications/publication/prevention-dune-reaction-dhypersensibilite-aux-agents-de-contraste.html

Year Published: 2025

URL for published report: https://www.inesss.qc.ca/publications/repertoire-des-publications/publication/prevention-dune-reaction-dhypersensibilite-aux-agents-de-contraste.html

English language abstract: An English language summary is available

Publication Type: Other

Country: Canada

Province: Quebec

Organisation Name: Institut national d'excellence en sante et en services sociaux

Contact Address: L'Institut national d'excellence en sante et en services sociaux (INESSS) , 2021, avenue Union, bureau 10.083, Montreal, Quebec, Canada, H3A 2S9;Tel: 1+514-873-2563, Fax: 1+514-873-1369

Contact Name: demande@inesss.qc.ca

Contact Email: demande@inesss.qc.ca

Copyright: L'Institut national d'excellence en sante et en services sociaux (INESSS)