Pre-Medication Policy

Pre-medication Policy (definitions of mild/moderate/severe below):

* If the clinician wishes the study to continue without pre-medication, this should be noted in the report.

** A patient with a well-documented history of a severe reaction to a contrast agent (oral or intravenous) should not receive the same contrast (oral or IV) unless, in the opinion of the responsible health care professional and supervising radiologist, the potential benefits outweigh the potential risks, such as in an emergency situation. In these instances, specific indications and reason(s) for exception should be documented in report.

*** With contrast of same type planned to be given. If the patient has received the same IV contrast in the past without an adverse event, then pre-medication may be omitted.

Pre-Medication Regimen

Discussion:

Even though a history of severe allergies is thought to predispose individuals to adverse reactions, it is probably only by a small percent, and most of the reactions will be minor. Thus, an allergic history, in and of itself, is not generally a reason to avoid injection of contrast media.

Any patient who describes an “allergy” to a food or anything else should be questioned further to clarify the type and severity of the “allergy” or reaction. True concern should be focused on patients with a history of a significant (severe, see below) reaction, regardless of the specific allergen. Note that there is no evidence that a prior reaction to shellfish confers a greater risk for an adverse event following exposure to an iodinated contrast agent than any other type of allergen.

• Asthma is considered to be a predictor of increased risk.
  • Asthma in and of itself, especially active asthma, increases the risk primarily of bronchospasm, not other adverse events.
  • But, many asthmatics also have allergies.

Types of Contrast Reactions and Recommendations for Pre-medication

Recommendations for pre-medication are based on the ACR Contrast Manual (Version 7) that divides contrast reactions into three groups:

Mild

• Nausea, vomiting
• Cough
• Warmth
• Headache
• Dizziness
• Shaking
• Altered taste
• Itching
• Pallor
• Flushing
• Chills
• Sweats
• Rash, hives
• Nasal stuffiness
• Swelling; eyes,face
• Anxiety

Moderate

• Tachycardia/bradycardia
• Hypertension
• Generalized or diffuse erythema
• Dyspnea
• Bronchospasm, wheezing
• Laryngeal edema
• Mild hypotension

Severe

• Convulsions
• Laryngeal edema (severe or rapidly progressing)
• Unresponsiveness
• Cardiopulmonary arrest
• Profound hypotension
• Clinically manifest arrhythmias

Although there is no cross reactivity, patients who have had previous allergic-like reactions to iodinated contrast media are also at risk from GBCAs, albeit probably at a lower level.

If a patient had a previous reaction to a GBCA, if possible, use a different GBCA for the next MRI exam.

Diagnostic Radiology Contrast Committee:

Rob Goodman
Gary Israel
Tom McCauley
Liane Philpotts
Gordon Sze
Jeff Weinreb                                                       
Dennis Cooper, Professor of Medicine                                      
Fred Kantor, Professor of Medicine (Immunology)