Premedication of patients for prior urticarial reaction to iodinated contrast medium Amy B. Kolbe, 1 Robert P. Hartman, 1 Tanya L. Hoskin, 2 Rickey E. Carter, 2 Daniel E. Maddox, 3 Christopher H. Hunt, 1 Gina K. Hesley 1 1 Department of Radiology, Mayo Clinic, 200 1st Street SW, Rochester, MN 55905, USA 2 Department of Health Sciences Research, Mayo Clinic, 200 1st Street SW, Rochester, MN 55905, USA 3 Department of Allergic Diseases, Mayo Clinic, 200 1st Street SW, Rochester, MN 55905, USA Abstract Purpose: The purpose of this study was to determine whether premedication of patients with a history of urticaria after low osmolality contrast media (LOCM) results in fewer subsequent reactions, and if a benefit is seen, to determine which premedication regimen results in the fewest reactions. Materials and methods: The subsequent contrast en- hanced studies of patients who experienced urticaria after intravenous LOCM between 2002 and 2009 were reviewed to determine whether an additional reaction occurred. Patients undergoing subsequent studies received either no premedication, or premedication with diphenhydramine alone, corticosteroid alone, or corticosteroid plus diphen- hydramine. Reactions occurring without premedication were termed repeat reactions and reactions occurring after premedication were termed breakthrough reactions. Results: Fifty patients with a history of urticaria after LOCM met the inclusion criteria and underwent 133 subsequent contrast enhanced studies. Repeat reactions occurred in 7.6% (5/66) of subsequent studies in patients receiving no premedication. Breakthrough reactions occurred in 8% (2/25), 46% (12/26), and 44% (7/16) of subsequent studies in patients receiving premedication with diphenhydramine, corticosteroid, and corticosteroid plus diphenhydramine, respectively. All subsequent reac- tions consisted of urticaria as the most severe manifesta- tion; no hemodynamic instability or respiratory compromise occurred. In multivariate analysis, premedi- cation with corticosteroid was significantly associated with higher rate of breakthrough reaction relative to no premedication (OR 14.3, 95% CI: 4.1–50.4), as was premedication with corticosteroid plus diphenhydramine (OR 8.3, 95% CI: 1.8–37.9). Conclusion: The results suggest that premedication of patients with a history of urticaria after LOCM may not be necessary. Key words: Iodinated contrast reaction—Contrast reaction—Premedication—Urticaria— Corticosteroid—Antihistamine The incidence of anaphylactoid reactions to iodinated contrast media has been extensively studied. Recent large-scale studies have reported the incidence of reac- tion to low osmolality contrast media (LOCM) as ranging from 0.5% to 3% [1–5]. The rate of severe reac- tions is extremely low from 0.01% to 0.04% [3–6]. However, considering that over 15 million intravenous iodinated contrast enhanced studies are performed each year [5], a significant number of reactions occur. Historically, after a patient experienced a reaction to iodinated contrast, corticosteroids, antihistamines, or a combination of both were administered prior to repeat contrast administration in attempts to prevent reactions. The most widely used premedication protocols, the Lasser protocol and the Greenberger protocol, were originally studied as prevention of reactions to ionic contrast media and showed a significant decrease in reactions [7–9]. The Lasser protocol includes two doses of methylprednisolone 32 mg orally administered 12 and 2 h prior to imaging. The Greenberger protocol includes three doses of prednisone 50 mg orally administered 13, 7, and 1 h prior to imaging. Diphenhydramine (25– 50 mg) may or may not be included with the cortico- steroids in either protocol. LOCM was subsequently shown to have a signifi- cantly better safety profile than high osmolar ionic con- trast media, with far fewer and less severe associated Correspondence to: Amy B. Kolbe; email: kolbe.amy@mayo.edu ª Springer Science+Business Media New York 2014 Published online: 5 January 2014 Abdominal Imaging Abdom Imaging (2014) 39:432–437 DOI: 10.1007/s00261-013-0058-9