Answer to Question #2440 Submitted to "Ask the Experts"

Q

I recently had a HIDA (hepatobiliary iminodiacetic acid) Scan done for some problems I had been having. I just found that I am pregnant and had to have been pregnant when I had the test done, but probably just a few days along. What kind of effects could the HIDA Scan have on my unborn child?

A

Your embryo was in the earliest stages of development that is referred to as the "All or None period", because it is most resistant to the malforming effects of radiation. Secondly because of the nature of the diagnostic studies, the embryo received a very low exposure, because the gall bladder x rays do not expose the embryo to radiation. Only a very small amount of scatter radiation will have reached the embryo. You did not tell me the amount of technetium that was administered in mCi (millicuries). However, since it was a diagnostic test it also should have only exposed the embryo to a very low dose. Summing up, the exposure should be well below the upper limit that would concern us and your risks for birth defects and miscarriage would be the background risks providing that you do not have other reproductive problems or a family history of reproductive problems. These background risks are 3% for birth effects and 15 % for miscarriage. Good luck with your pregnancy.

Robert Brent MD, PhD, DSc