Contrast Agents: What Should Nurses Know?

"CT scan with and without IV contrast!" You may have heard this phrase over and over again in your practice, but how much do you really know about contrast agents? Radiology nurses and technicians administer contrast to patients undergoing radiographic tests and procedures. Although floor nurses may not frequently administer contrast regularly aside from the occasional oral contrast, it is important for them to know how these chemicals affect the body. Did you know that some contrasts can cause adverse effects in patients for as long as a week after administration?

This is one reason why all nurses should become familiar with contrast agents and how they can affect their patients. You may find that your patient's rapid pulse isn't simply a result of pain or stress. It could be an adverse effect from the intravenous (IV) contrast they received during the computed tomography (CT) scan they underwent just a few hours before.

Interested to know more? Read more to learn about contrast agents and myths surrounding their use.

What Are Contrast Agents?

Contrast agents are chemicals and other substances administered during diagnostic tests to help highlight bodily structures on imaging. They are used to rule out tumors, lesions, and other abnormalities. While most commonly administered through an IV, contrast agents can also be administered by mouth, or into an ostomy, the epidural space, bladder, rectum, or joint spaces. Let's discuss oral and IV contrast.

Oral Contrast

Barium is a well-known oral contrast. However, iodinated oral contrast agents exist as well, but are not used as often because of cost and taste. Barium is used during gastrointestinal diagnostic tests and typically comes in a powder that must be mixed with water and consumed. Barium can cause nausea, abdominal pain, electrolyte imbalances, and vasovagal reactions related to the bowel distention that occurs after consumption.

Something to think about: Would you ever think to attribute your patients' vasovagal symptoms to the oral contrast agent they just consumed?

IV Contrast

IV contrasts typically enter the extracellular space to help highlight the separation between tissues, essentially outlining tumors and lesions. Contrasts help clinicians visualize structures better through opacification (gray areas on images indicating a solid structure is present). IV contrasts are administered during many diagnostic tests, including CT, magnetic resonance imaging (MRI), and ultrasound imaging.

Computed Tomography Studies

When you hear contrast agent, which one comes to mind? The most well-known contrast is CT contrast (or iodinated IV contrast). Composed of iodine, a naturally occurring element in the body, this type of contrast is known to diffuse into the extracellular space in less than 20 minutes. Iodinated IV contrast can cause allergic reactions (from itching to throat swelling) and physiologic reactions (such as high blood pressure, seizure, or kidney damage).

Something to think about: How often have you struggled with singling out the cause of your patient's sudden high blood pressure? Did you ever suspect IV contrast to be the culprit?

Magnetic Resonance Imaging Studies

Contrasts used during MRIs are called gadolinium-based contrast agents (GBCAs). Similar to iodinated IV contrast, GBCAs are composed of a naturally occurring metal. Gadolinium is a heavy metal that is naturally found in the earth, but is toxic to humans in its natural form. The gadolinium in GBCAs is chemically changed to make it non-toxic. These contrasts can cause reactions including headache, nausea, rash, and distorted taste.

Something to think about: If your patient reports that their lunch tastes funny, should you investigate further? Did they just have an MRI? Might they be experiencing distorted taste due to the contrast?

Ultrasound Imaging

Although uncommon, IV contrast is used during ultrasounds (fun fact: IV contrast was once regularly used for X-rays in the past). Unlike contrasts for CTs and MRIs, which are chemical-based, contrast for ultrasounds consists of tiny bubbles of air or gas infused into a substance (such as saline, fat, or crystals) which is injected into an IV or body cavity. Ultrasound contrasts are not as popular in the United States aside from their use during some cardiology exams.

What Are the Myths about Contrast Agents?

Before reading this blog, what was one fact you heard over and over again about contrasts? Is it that they should not be administered to patients with a shellfish allergy? How about that they should not be administered to patients with kidney disease? Let's debunk these three common myths about contrast agents.

Myth 1: CT and MRI imaging are the only diagnostic tests that use IV contrast.

As mentioned above, IV contrast agents are used in CT, MRI, and some ultrasound studies. In fact, ultrasound contrast is safer to use as it generally does not cause kidney problems.

Myth 2: Patients with shellfish allergies automatically have iodine allergies.

Shellfish allergies and iodine allergies are unrelated. In fact, an iodine allergy is not a true allergy, as iodine is a naturally occurring element that we need to survive. Although iodinated contrast reactions are real, they are still unrelated to shellfish allergies.

Myth 3: Patients with kidney disease cannot have IV contrast.

Kidney disease is not an absolute contraindication for IV contrast. Patients with kidney disease can receive IV contrast on a case-by-case basis based on risk severity, type of contrast used, and dose administered.

There are even more myths out there about contrasts that have been debunked. If you are interested in learning more, take the CEUFast course titled Adverse Effects of Contrast Agents: Dispelling the Myths. In this course, you will not only learn more about contrast agents and how they work, but you will also learn about the vast adverse effects that can occur and how to address them most appropriately.

Bottom Line

Contrast agents are not only pertinent to radiology technicians or nurses working in radiology. All nurses should be aware of the contrast agents administered to their patients, as they can cause reactions well beyond the time spent in the radiology department. It is also important for nurses to dispel myths surrounding contrast use, as they can negatively impact patients.

About the Author:

Charmaine Robinson, MSN-Ed, BSN, RN, is a nurse writer with a background in medical-surgical nursing and nursing instruction.

Charmaine is an independent contributor to CEUfast's Nursing Blog Program. Please note that the views, thoughts, and opinions expressed in this blog post are solely those of the independent contributor and do not necessarily represent those of CEUfast. This blog post is not medical advice. Always consult with your healthcare provider for any health-related questions or concerns.

If you want to learn more about CEUfast's Nursing Blog Program or would like to submit a blog post for consideration, please visithttps://ceufast.com/blog/submissions.