allergy testing with contrast allergy

[bedrock]

During fellowship we sent quite a few patients with questionable contrast allergies to the university allergy dept for skin testing. Now in private practice all the local allergists in my town are saying they can't do skin tests for contrast allergies?

Do my local allergy docs just suck? Does anyone else on the board ever send their patients for contrast allergy testing?
I do 90% of my procedures in the office and I'm not excited about doing a cervical ESI on these patients even with premedication.

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[lobelsteve]

Never seen contrast allergy. Have seen 100s of reported iodine, seafood, and iv dye allergies reported by patients. None of them had adverse event with omnipaque.

 

[mid|ine]

I use gadolinium if the report iodine, seafood, or iv dye allergies

 

[clubdeac]

Never seen contrast allergy. Have seen 100s of reported iodine, seafood, and iv dye allergies reported by patients. None of them had adverse event with omnipaque.

So Steve, you still use omnipaque on all your patients with iodine, seafood or IV dye allergies??? I agree that seafood allergy is probably irrelevant and there is no cross reactivity but I still use gad for those with apparent iodine or contrast allergy.

 

[lobelsteve]

So Steve, you still use omnipaque on all your patients with iodine, seafood or IV dye allergies??? I agree that seafood allergy is probably irrelevant and there is no cross reactivity but I still use gad for those with apparent iodine or contrast allergy.

All of them.


Seafood allergy bears no relation, iodine allergy bears little relation, and IV contrast allergy is almost always related to the disease process and not the contrast, or is of the severity of an intolerance or expected side effect.

Clinical Implications

Patients reporting iodine or seafood allergy should be questioned as to the exact nature and severity of the reaction. If possible, seafood allergy should be distinguished from other causes of seafood intolerance. The presence of a seafood allergy places the patient at a threefold risk of an adverse reaction to contrast material. As with any other allergy, the nature and severity of the reaction should be considered when choosing the type of contrast material and when determining the need for a premedication regimen. Seafood allergy should not of itself be regarded as an absolute contraindication to the administration of IV contrast material. There is no reason to believe that iodine allergy based on skin reactions to topical antiseptics is of any specific relevance to the administration of IV contrast material.


If anaphylaxis is reported after IV contrast administration, I would not use contrast. I have never seen this patient. Careful history eliminates 99+% of all allergies.

 

[mid|ine]

Agree that 99.9% of the time its not required, however its just CYA.

 

[emd123]

I've given contrast to dozens maybe hundreds of patients pre-ct scan (non-anesthesia background ) with mild to moderate contrast allergies. 125mg solumedrol iv and 50 mg benadryl iv 20-30 min prior. I've never had one have a significant reaction that i can recall (same meds I'd give for an actual reaction). For life threatening reactions, no contrast for any reason. Not for an elective procedure. Contrast rarely makes a life saving difference in any setting. Send someone to an allergist? Probably not worth the trouble. If it's a mild or questionable allergy, just pre-treat them. If it's a severe allergy, just stop there, not worth the risk. The vast majority are "iffy" reactions such as flushing, nausea, mild rash. Acute treatment for even severe allergic reactions in general almost always works, and quickly, if dealt with promptly and correctly. Iv benadryl, solumedrol, pepcid (add epi if it involves airway or hypotension). I've seen one patient die before my eyes of an alleric reaction (not to contrast) despite all these meds, but she had a congenital propensity to overwhelming allergic reactions (hereditary mastocytosis). It wasn't pretty.

 

[drf]

All of them.


Seafood allergy bears no relation, iodine allergy bears little relation, and IV contrast allergy is almost always related to the disease process and not the contrast, or is of the severity of an intolerance or expected side effect.

Clinical Implications

Patients reporting iodine or seafood allergy should be questioned as to the exact nature and severity of the reaction. If possible, seafood allergy should be distinguished from other causes of seafood intolerance. The presence of a seafood allergy places the patient at a threefold risk of an adverse reaction to contrast material. As with any other allergy, the nature and severity of the reaction should be considered when choosing the type of contrast material and when determining the need for a premedication regimen. Seafood allergy should not of itself be regarded as an absolute contraindication to the administration of IV contrast material. There is no reason to believe that iodine allergy based on skin reactions to topical antiseptics is of any specific relevance to the administration of IV contrast material.


If anaphylaxis is reported after IV contrast administration, I would not use contrast. I have never seen this patient. Careful history eliminates 99+% of all allergies.

Agreed. I will also add that people aren't allergic to iodine in seafood (an element is not antigenic); they are allergic to specific proteins.

I use a history of iodine/seafood/IV contrast allergy mostly as a marker for increased susceptibility to have allergic reactions in general. I don't think there is otherwise a relationship between the agents.

 

[Tenesma]

what data do you have that shows seafood allergy increases the risk of contrast allergy??

i am not aware of any such proven correlation...

I have NEVER had contrast related anaphylaxis - but i do pre-medicate all of my "allergy" patients with prednisone and benadryl pre-procedure...

i have had a few patients with urticaria who responded well to a dose of solumedrol...

 

[MATV78]

Hi I'm an allergist, too bad you can not rely on them for "testing". Agree with history as the most important test. Skin testing which assesses immediate hypersensitivity (IgE mediated) is of no help since reactions from RCM are non-IgE mediated. There is no skin testing for RCM, but thats why we are here to help when you need an answer.

Below is from Allergy and Immunology practice parameters Drug Allergy. This section deals with RCM.

Hope it is of some use.

B. Radiocontrast Media
Radiocontrast media containing organic iodine may cause adverse reactions such as generalized urticaria/angioedema, bronchospasm, laryngospasm, shock, and death. A review of 10,000 consecu- tive intravenous urograms reveals that the incidence of pseudoallergic reactions is 1.7%.154 The frequency of fatal reac- tions is 1 in 50,000 intravenous poly- gram procedures.155 These adverse reac- tions are not mediated by specific IgE antibodies. Only 16% of individuals with a previous immediate generalized reaction after intravenous injection of io- dinated radiographic compound respond with symptoms on the second chal- lenge.156 If these reactions had been me- diated by specific IgE, it would be ex- pected that a higher percentage of such patients would have experienced gener- alized reactions after the second chal- lenge dose. No single pathogenic mech- anism accounts for these unpredictable clinical manifestations but it is likely that mast cell activation accounts for the ma-
jority of these reactions. Activation of complement components has been de- scribed but not in all cases. Radiocon- trast media can also cause intravascular volume expansion and precipitate “car- diogenic” pulmonary edema in patients with ischemic cardiac heart disease.157

There is no evidence that sensitivity to seafood or “iodine” predisposes or is cross-reactive with RCM reactions. Al- though predictive tests are not available, patients with documented atopic profiles and those using beta blocking agents ap- pear to be at significant risk for RCM anaphylactoid reactions.158,159
Management of a patient who re- quires RCM and has had a prior reac- tion to RCM includes the following (1) determine if the study is essential; (2) determine that the patient under- stands the risks; (3) ensure proper hy- dration; (4) use a non-ionic, lower os- molar RCM, especially in high risk patients (asthmatic patients, patients on beta blockers and those with cardio- vascular disease)160 and (5) use a pre- treatment regimen which has been doc- umented to be successful in preventing most reactions.161 One reported regi- men consists of prednisone 50 mg (p.o.) 13, 7, and 1 hours before the procedure, diphenhydramine 50 mg one hour before the procedure and ei- ther ephedrine 25 mg or albuterol 4 mg 1 hour prior to the procedure. Some investigators prefer combining an H2 antagonist with the H1 antago- nist one hour before the procedure and omitting ephedrine or albuterol.

 

[bedrock]

Thanks for everyone's comments, very helpful.