From the Guidelines
Delayed contrast reactions should be treated based on symptom severity, with mild to moderate reactions managed with oral antihistamines and topical steroids, and severe reactions requiring oral prednisone and potentially emergency care. The management of delayed contrast reactions is crucial to prevent further complications and improve patient outcomes. According to the evidence, patients with a history of delayed contrast reactions have a 30-50% risk of recurrence with future contrast exposure 1.
Treatment of Delayed Contrast Reactions
- For mild to moderate reactions (rash, itching, mild swelling), oral antihistamines like diphenhydramine 25-50mg every 6 hours or cetirizine 10mg daily are recommended.
- For skin reactions, topical steroids such as hydrocortisone 1% cream applied 2-3 times daily may help.
- Severe reactions with extensive rash, significant swelling, or systemic symptoms require oral prednisone 40-60mg daily for 3-5 days with a taper.
- Patients experiencing breathing difficulties, severe swelling, or hypotension should seek immediate emergency care.
Premedication for Future Contrast Studies
Premedication for future contrast studies may include prednisone 50mg at 13,7, and 1 hour before contrast administration, plus diphenhydramine 50mg 1 hour before contrast 1. However, the evidence suggests that premedication does not provide clear benefit in preventing recurrent severe delayed onset reactions 1.
Importance of Documenting Reactions
Documenting the reaction is important for future imaging decisions, as patients with a history of delayed contrast reactions have a significant risk of recurrence. The optimal approach to patients with delayed severe RCM reactions requires further study 1.
From the Research
Delayed Contrast Reaction
- Delayed contrast reactions are adverse events that occur more than 1 hour after contrast medium administration 2.
- These reactions can be mild to moderate skin reactions, such as maculopapular exanthematous and urticarial/angioedematous types, and are reported to occur in 0.5-2% of recipients 2.
- The incidence of more severe reactions is extremely low, but main risk factors for delayed allergy-like reactions appear to be a previous contrast medium reaction, a history of allergy, IL-2 treatment, and being of Japanese descent 2.
- Delayed adverse reactions to contrast media are not rare, but are often not recognized as being linked to contrast administration and may be falsely ascribed to other drugs 3.
- The exact pathogenesis of these delayed reactions is still unclear, but there is increasing evidence that a significant proportion of the reactions are T-cell mediated 2.
Clinical Manifestations and Treatment
- The signs and symptoms of a severe reaction, such as anaphylaxis, and the dose and methods of epinephrine administration are important for all radiologists to master 4.
- A thorough knowledge of the clinical features, their adequate treatment, and, possibly, the subsequent diagnostic procedure for preventing recurrence after reexposure to CM would improve patient management 5.
- Epinephrine is the most important treatment for severe allergic-like contrast reactions 4.
Prevention and Management
- Appropriate contrast reaction management is necessary for the best patient outcome, and preventative strategies can help mitigate adverse contrast events 6.
- Systematic limitations in the training of current and future radiologists can be improved with strategies such as education on contrast reaction management and treatment algorithms 4.