Answer to Question #374 Submitted to "Ask the Experts"

Q

I am in my eighth week of pregnancy. In the beginning of my pregnancy, around two weeks, I had some abdominal x rays and a CT scan done of my abdomen. I've read that the damage from the abdominal x ray is minimal, but what about the CT scan? What possible damage can occur (if any) from that?

A

We told the person asking this question that the conceptus dose from such a CT examination is between 12 mGy and 30 mGy (1.2 rad and 3 rad) according to Exposure of the Pregnant Patient to Diagnostic Radiations, (Medical Physics Publishing, Madison, Wisconsin). However, we cautioned her that the precise dose depends on the machine and techniques used, the size of the patient, etc. We pointed out that the National Council on Radiation Protection, 1977, said: "The risk [of abnormaility] is considered to be negligible at 5 rad or less when compared to other risks of pregnancy, and the risk of malformations is significantly increased above control levels only at doses above 15 rad. Therefore, exposure of the fetus to radiation arising from diagnostic procedures would very rarely be cause, by itself, for terminating a pregnancy." We suggested that she get specific information on the dose to the conceptus from the procedure she had and, that if she had any further questions, she personally contact our expert on radiation exposures during pregnancy. Her reply to us was: "Thank you so much for the information! I feel very reassured. I was searching all over the Web looking for information on CTs during pregnancy and found nothing until I found your site. "

Genevieve S. Roessler, PhD
Editor, HPS website