Ask the Clinical Instructor: A Q&A Column for Those New to the Cath Lab

A couple of years ago, you published an article about contrast allergies. If I recall, you mentioned lack of evidence between shrimp allergies and seafood allergies. Our department is trying to develop some standards around this, but cannot find any specific standards. Can you help? — Anonymous via RCIS Review Facebook page.

There was an article in February 2009 that discussed some of the ins and outs of contrast allergies (available on the CLD website at https://tinyurl.com/CLDFeb09).

I hear about cath labs where the question about shellfish/shrimp allergies is still included in the initial assessment of the patient. When we stop and ask why we do that, the answer is often, “Well, that’s just what we have always done.” In the article from 2009, I showed a reference to the fact that the allergy to shrimp/shellfish is due to the muscle proteins in the seafood, which is not present in iodine-based contrast.

Even with this being an anecdotal link, it is still in practice today. If you do research on this topic, you will have difficulty finding a specific standard. However, in 2010, the American College of Radiology published the “ACR Manual on Contrast Media Version 7 2010 — ACR Committee on Drugs and Contrast Media” (Available online at https://www.acr.org/secondarymainmenucategories/quality_safety/contrast_manual.aspx). In this manual, some statements are made about the link between shellfish and contrast allergies:

“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.” 

In regards to regular questioning of the patient about their seafood allergies:

“There is no evidence to support the continuation of this practice.”

While this document represents a group approach to this allergy linkage, it is also understood that the practice of this question is up to the physician to use or not to use. Perhaps, if the physician doesn’t require it, this can become the standard that we all operate under.

In coming months, we will address a question somewhat related to this — premedication for contrast allergies, effective or not?

Todd is the Cardiology Manager for Memorial Hermann Southeast in Houston, Texas. He also teaches an online RCIS Review course for Spokane Community College, in Spokane, Washington, and regularly presents with RCIS Review Courses.

Email your question to Todd Ginapp at tginapp@rcisreview.com, or post it on www.facebook.com/rcisreview.