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Everything you need to know about Computed Tomography (CT) & CT Scanning

Reactions and Complications

question1. How often do contrast reactions occur to IV contrast? Are there patients at increased risk?

This is dependent on a number of factors including patient risk profile as well as contrast material used. Some guidelines that are in the published literature are as follows

  • Mild acute reactions occur in up to 3% of patients receiving non-ionic contrast
  • Moderate reactions occur in 0.2-0.4% of patients receiving non-ionic contrast
  • Severe reactions occur in 0.04% of patients receiving non-ionic contrast

Adverse reactions to Intravenous Iodinated Contrast Media: A Primer for Radiologists
Namasivayam S et al.
Emerg Radiol (2006)12; 210-215

"Allergic type reactions in 545 (O.6%) of patients injected with nonionic contrast media: 418 (77%) reactions were mild, 116 (21%) were moderate, and 11 (2%) were severe. 221 patients (41%) received treatment. Although 99% of the treatments did not result in any complication, 3 patients may have had short term sequelae as a result of receiving a nonrecommended treatment ” "

Frequency, Outcome and Appropriateness of Treatment of Nonionic Iodinated Contrast Media Reactions
Wang CL et al
AJR 2008;191:409-415

"The predictive value of specific allergies, such as those to shellfish or dairy products, previously thought to be helpful, is now recognized to be unreliable. A significant number of health care providers continue to inquire specifically into a patient's history of "allergy" to seafood, especially shellfish. There is no evidence to support the continuation of this practice."

ACR Manual on Contrast Media
Version 9 (2013)

"Patients with significant cardiac disease may be at increased risk for contrast reactions. These include symptomatic patients (e.g., patients with angina or congestive heart failure symptoms with minimal exertion) and also patients with severe aortic stenosis, primary pulmonary hypertension, or severe but well-compensated cardiomyopathy. In all such patients, attention should be paid to limiting the volume and osmolality of the contrast media."

ACR Manual on Contrast Media
Version 9 (2013)

"Patients usually do well after developing acute allergic like reactions to nonionic iodinated contrast media. Fortunately, in our series, this was true even in the rare cases in which the instituted treatment was considered to be inappropriate."

Frequency, Outcome and Appropriateness of Treatment of Nonionic Iodinated Contrast Media Reactions
Wang CL et al
AJR 2008;191:409-415
question2. Although most iodinated contrast reactions are typically mild, what is the long term sequelae to the patient who gets a reaction?
question3. Are there specific patients or risk factors that make it more likely to get a contrast reaction?
question4. Will faster injection rates (5 cc/sec vs. 1 cc/sec) result in an increased incidence of contrast reactions?
question5. What are the categories of contrast reactions?
question6. Death is one of the potential complications of IV contrast. How often does this occur?
question7. What are the risks of IV contrast in terms of renal failure (CIN)? How often does CIN occur? How we prevent CIN?
question8. Who can not get IV contrast material?

Allergic Reactions


1. Part 1: Can a patient get a rash from IV contrast? Can it occur 24-36 hours post CT study?

Part 2: How do you treat the rash?

question2. Is it possible for a patient to get a delayed reaction to IV contrast?
question3. What if a patient is allergic to IV contrast material?

4. Part 1: What patients are allergic to IV contrast?

Part 2: Can we premedicate these patients and if yes what is our premedication protocol?

question5. Our patient needs the study now. What else can we do?
question6. The patient is allergic to shellfish or crabs. Can they get a IV contrast?


question1. What is contrast extravasation and how often does it occur?
question2. How do you prevent contrast extravasation?

3. Part 1: How do we treat contrast extravasation when it happens?

Part 2: Is cold compresses the rule or hot compresses?
question4. What if extravasation does occur. How often are there severe complication?


© 1999-2020 Elliot K. Fishman, MD, FACR. All rights reserved.