1. Men's Screening Tests Slideshow
2. Women's Screening Tests Slideshow

Medical Author:

Melissa Conrad Stöppler, MD

Melissa Conrad Stöppler, MD

Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.

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Medical Editor:

Charles Patrick Davis, MD, PhD

Charles Patrick Davis, MD, PhD

Dr. Charles "Pat" Davis, MD, PhD, is a board certified Emergency Medicine doctor who currently practices as a consultant and staff member for hospitals. He has a PhD in Microbiology (UT at Austin), and the MD (Univ. Texas Medical Branch, Galveston). He is a Clinical Professor (retired) in the Division of Emergency Medicine, UT Health Science Center at San Antonio, and has been the Chief of Emergency Medicine at UT Medical Branch and at UTHSCSA with over 250 publications.

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In this Article

• CT scan facts
• What is a CT scan?
• Why are CT scans performed?
• Are there risks in obtaining a CT scan?
• How does a patient prepare for CT scanning, and how is it performed?
• Patient Comments: CT Scan - Helped With Your Diagnosis
• Patient Comments: CT Scan (Computerized Axial Tomography) - Causes
• Find a local Doctor in your town
• CAT Scan Index

Are there risks in obtaining a CT scan?

A CT scan is a very low-risk procedure. The most common problem is an adverse reaction to intravenous contrast material. Intravenous contrast is usually an iodine-based liquid given in the vein, which makes many organs and structures, such as the kidneys and blood vessels, much more visible on the CT scan. There may be resulting itching, a rash, hives, or a feeling of warmth throughout the body. These are usually self-limiting reactions that go away rather quickly. If needed, antihistamines can be given to help relieve the symptoms. A more serious allergic reaction to intravenous contrast is called an anaphylactic reaction. When this occurs, the patient may experience severe hives and/or extreme difficulty in breathing. This reaction is quite rare, but is potentially life-threatening if not treated. Medications which may include corticosteroids, antihistamines, and epinephrine can reverse this adverse reaction.

Toxicity to the kidneys which can result in kidney failure is an extremely rare complication of the intravenous contrast material used in CT scans. People with diabetes, dehydrated individuals, or patients who already have impaired kidney function are most prone to this reaction. Newer intravenous contrast agents have been developed, such as Isovue, which have nearly eliminated this complication.

The amount of radiation a person receives during a CT scan is minimal. In men and nonpregnant women, it has not been shown to produce any adverse effects. If a woman is pregnant, there may be a potential risk to the fetus, especially in the first trimester of the pregnancy. If a woman is pregnant, she should inform her doctor of her condition and discuss other potential methods of imaging, such as an ultrasound, which are not harmful to the fetus. However, most physicians suggest that all radiation exposure to patients should be kept to a minimum; those patients that “doctor shop” or repeatedly go to emergency departments for a "CT” put themselves at risk for radiation-caused problems.