Answer to Question #1439 Submitted to "Ask the Experts"

Q

I am 31 weeks pregnant and my doctor has highly recommended a QV scan or a CT scan as he suspects a blood clot in my lung—pulmonary embolism. Which test offers the lowest risk to the baby while giving me the most accurate results, and are there certain questions I should ask the radiologist (rad dosage limits) before proceeding?

A

The first priority you have is to make the correct diagnosis of the problem in your lung. Therefore your physician should select the best diagnostic test. That is most important for you and your baby. I understand your concern and I will try to explain why your anxiety and concern is not warranted in your present situation. When you receive a diagnostic x-ray study of your head, teeth, chest, arms, or legs at a qualified facility, the exposure by the x rays is not to your embryo. The "scatter" that might reach the embryo would be extremely small and would not present 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 would not receive a dose from these procedures that would result in any measurable increased reproductive risk. If you are healthy and 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