Answer to Question #12941 Submitted to "Ask the Experts"

Category: Pregnancy and Radiation — Exposures to embryo/fetus

The following question was answered by an expert in the appropriate field:


Last week my girlfriend received an abdominal computerized tomography (CT) scan at 12 weeks of fetus development which is right in the middle of the highest risk period of 8–15 weeks. The test was ordered by her general practitioner because she was complaining of abdominal pain and a distended stomach. I'm looking for recommendations on specific actions to take now to assess the risk and locate the right resources.

Is a maternal fetal medicine specialist someone who specializes in radiology? We want to locate the best possible resource.


It is highly unlikely that the low radiation dose received from the CT scan will cause harmful effects for the fetus. 

The radiation dose to the fetus from an abdominal CT procedure will vary depending on the equipment, scanning parameters used, and patient size. An average dose would be around 4 milligray (mGy—a unit of radiation absorbed dose) with and without contrast. The publications I've listed below will give you more detail on the doses.

The radiation dose necessary to cause fetal harm ranges from 100 mGy and upward between weeks 8 and 15. The radiation dose received by your girlfriend was much lower than this (by a factor of 25) and not expected to cause harmful effects.

Most diagnostic procedures that expose the abdomen or pelvis to radiation when you are pregnant will not harm the fetus. The radiation doses are too low.

As for your question about a maternal fetal medicine specialist, I doubt they would know much about radiation, radiation doses, and effects on pregnancy. The person at a hospital who often knows the most about radiation effects is a radiologist (diagnostic radiation specialist) or radiation oncologist (radiation therapy cancer specialist) or a nuclear medicine physician (radiopharmaceutical use specialist).

Kelly Classic
Certified Medical Health Physicist

Publications that may be of interest: 

  • Hall EJ and Giaccia AJ. Radiobiology for the radiologist. 6th Ed. Lippincott Williams & Wilkins, New York. 2006.
  • Mettler FA and Upton AC. Medical effects of ionizing radiation. 6th Ed. London: WB Saunders Company; 1995.
  • McCollough CH, Schueler BA, Atwell TD, Braun NN, Regner DM, Brown DL, LeRoy AJ. Radiation exposure and pregnancy: when should we be concerned? Radiographics 27(4):2007. Available at Accessed 19 May 2019.
  • Nikolic B, Spies JB, Lunsten MJ, Abbara S. Patient radiation dose associated with uterine artery embolization. Med Phys: January 2000.
Ask the Experts is posting answers using only SI (the International System of Units) in accordance with international practice. To convert these to traditional units we have prepared a conversion table. You can also view a diagram to help put the radiation information presented in this question and answer in perspective. Explanations of radiation terms can be found here.
Answer posted on 20 May 2019. The information posted on this web page is intended as general reference information only. Specific facts and circumstances may affect the applicability of concepts, materials, and information described herein. The information provided is not a substitute for professional advice and should not be relied upon in the absence of such professional advice. To the best of our knowledge, answers are correct at the time they are posted. Be advised that over time, requirements could change, new data could be made available, and Internet links could change, affecting the correctness of the answers. Answers are the professional opinions of the expert responding to each question; they do not necessarily represent the position of the Health Physics Society.