Incidence of Breakthrough Reaction in Patients with Prior Acute Allergic-Like Reactions to Iodinated Contrast Media according to the Administration Route.

Objective: This study assessed the risk of acute allergic-like reactions (AARs) after extravascular administration of iodinated contrast media (ICM) in at-risk patients compared with that after intravascular ICM administration. Materials and Methods: From July 2012 to January 2016, 264 patients with a history of moderate or severe reactions to ICM, with re-exposure to ICM intravascularly or extravascularly were included. The incidence of recurrent AARs after ICM re-exposure were assessed according to the administration routes by reviewing electronic medical records and comparison between the two routes. Results: Among 264 patients, 244 patients had been subsequently exposed to ICM intravascularly, 7 patients via an extravascular route and 13 patients with dual re-exposure. Of 257 patients with intravascular ICM re-exposure, 87 (33.9%) had mild to severe recurrent AARs and 143 (19.5%) cases of recurrent AARs occurred among 733 cases of intravascular ICM re-exposure on a case-by-case basis. However, there was no case of recurrent ARR after extravascular administration of ICM in 20 patients (45 cases) with ICM administrated extravascularly. Conclusion: For high-risk patients with a history of moderate or severe reactions to ICM, AARs upon extravascular administration of ICM are significantly infrequent compared with intravascular ICM administration.