The following may affect you being able to have a CT scan:
- Known or possible pregnancy
- Barium used for another test. These substances show up on a CT scan. If a CT scan of your belly is needed, it should be done before any tests that use barium.
- You are not able to lie still during the exam.
- Metal objects in the body, such as surgical slips or metal in joint replacements, may prevent a clear view of the area of interest.
A CT scan is a very safe study. Although CT exams require the use of ionizing radiation (x-ray) and there is a slight risk from x-ray radiation exposure, the amount of radiation used is minimized by advanced CT detectors and computer technology to achieve the best image quality at the lowest possible radiation dose. Also, protective shielding is used routinely to prevent unnecessary radiation exposure.
For CT examinations performed WITHOUT intravenous contrast, there is no risk involved in the exam unless you are or may be pregnant. The risks and benefits of having the CT scan should then be discussed with your doctor to determine the best course of action.
For CT examinations performed WITH intravenous iodinated contrast, most patients have no reaction or side effects. However, as with most diagnostically beneficial medical examinations, there are certain risks. The risks are related to allergic and non-allergic reactions to the injected contrast.
Minor reactions to the IV contrast used for CT scan may include nausea, vomiting, headache or dizziness, which are usually of short duration and usually require no treatment. Sometimes there are cases of hives (urticaria) and rash, which we can treat with antihistamines or other medications. Rarely, asthma can be induced, which is also treatable.
More serious reactions to the IV contrast used for CT scan, such as blood clotting, kidney damage, inflammation of a vein (phlebitis), shock and fatal reactions have occurred but only rarely. The incidence of fatal reaction is less than 1 in 100,000 patients receiving IV contrast with iodine, which is much less than reactions to many antibiotics and other medications used daily in medical practice.
If you would like more information or have any questions about the use of IV contrast, the CT staff and/or radiologist will speak with you at the time of your appointment. Also, please see the “if contrast is used section” for further information regarding the use of IV contrast.
If you are breastfeeding and receive IV contrast, you will need to use formula for 2 days after your CT scan so that you do not pass the dye to your baby. You should throw out any breast milk you collect during this time.