Answer to Question #3746 Submitted to "Ask the Experts"

I am a medical student and am currently five weeks pregnant. As part of my clinical rotation in internal medicine, I examine hospitalized patients, many of whom who have had thyroid scans, cardiolyte stress tests, and other procedures involving radioactive agents. What risks do these types of exposure pose to my unborn baby? Are there precautions I can take, for example, should I wear gloves when examining these patients? Is it unsafe for me to be in the patient's room when they are getting a contrast injection? Are there certain patients I should avoid entirely? Thanks for offering this service and for any help you can provide.

Remember many of the tests that concern you can be performed on a pregnant woman. The most important determinant about risk is the dose. When the isotope (radionuclide) is given to someone else the exposure to the medical personnel is much smaller than the patient receives and with some radionuclides, there may be no exposure to the medical personnel. Your developing embryo is not at risk

If wearing gloves makes you feel more secure, then wear them, but in most instances it is not necessary. The "scatter" that might reach the embryo would be extremely small and would not represent an increased risk for birth defects or miscarriage to your embryo. The most important characteristic of x rays that concerns us is the dose. You may not know that we ourselves are radioactive and we are exposed to many sources of natural radiation that we cannot avoid. Your developing embryo will not receive a dose that would result in any measurable increased reproductive risk. If you are healthy, young, and have no reproductive problems or family history of reproductive problems your risk for birth defects is 3% and for miscarriage, 15%. Neither you nor I can change that risk which all mothers have when they begin a pregnancy. Good luck with your pregnancy.

Robert L. Brent MD, PhD