Today, I will talk about pregnancy and X-ray. Generally, the amount of radiation is extremely low in X-ray, so radiation exposure of children or adults is not taken seriously. However, What about pregnant women?

Q: I am pregnant, but I took an X-ray, is it okay?

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Cf.) The unit ‘mGy’ used in the following article means the unit of radiation dose.

What is the effect of X-ray on the fetus?

First, let's find out the impact of X-ray on the fetus.

1. Miscarriage: In case of exposure to x-ray within 1-2 weeks after fertilization, Complete recovery or death of the embryo occurs.

2. Deformity or Developmental abnormality: 3-8 weeks are the period of formation of the organs, so there is a high risk of malformations due to radiation exposure in this period.

3. Intellectual degradation: 10-17 weeks are the central nervous system formation stage, which affects brain formation and function. Above 100mGy, a decrease in intelligence occurs, and 1Gy causes severe mental retardation. IQ decreases per 0.025/mGy.

4. Pediatric cancer : It is predicted that childhood cancer and leukemia will increase in case of exposure to radiation during the first trimester. However, the minimum dose has not been established yet. According to studies, it is difficult to estimate the potential risk of cancer caused by exposure to radiation during pregnancy.

To conclude, effects of radiation usually occurs at over 100mGy. In early pregnancy, fetal death happens or there is no effect caused by radiation. Thereafter, abnormalities are accompanied according to the developmental stage of the fetus. Radiation risk is highest in organs formation period and in the first trimester, and the effect becomes lower in the second trimester. However, it is difficult to estimate the risk for pediatric cancer.

How much is 100mGy?

Usual a single general X-ray inspection dose < 4mGy, and a single CT dose <50mGy

Most fetal radiation exposures happen in CT scans of the pelvis containing the uterus. In case of general X-ray inspections, only about 4mGy of radiation is used even in a pelvic irradiation. Therefore, in order to reach 100mGy, about 25 times of X-ray inspections should be made. You do not have to worry about one accidental X-ray inspection, but it is better to avoid it just in case.

Can I take an X-ray while planning to be pregnant?

There has been no report that radiation exposure of the parent gonads before pregnancy causes increase in cancer or malformations in children. In many hospitals, when a fertile woman visits a clinic, she is asked whether she is pregnant orally before the X-ray inspection, or a urine test is performed to confirm pregnancy. And there is always a notice or warning in the X-ray room. However, if you are not urgent, you may be advised to take an X-ray within 10 days of the last menstrual cycle to avoid the possibility of pregnancy.

There is always a warning in the X-ray room
From: http://www.airforcemedicine.af.mil/MTF/Malmstrom/News-Events/Article/1086621/radiology-capturing-life-saving-images/

Is there any situation when I cannot avoid X-ray inspection?

Of course, it happens. Patients with suspected pneumonia or suspected fractures may require X-ray or CT. In this case, the abdomen in which the fetus is located is covered with a shield which prevents the radiation. Especially for non-abdominal examinations, the radiation exposure of the fetus is insignificant. If the stomach is sore and needs inspection, we use ultrasound or MRI without radiation. If you tell that you are pregnant, the inspection is always carried out in consideration of radiation.

Acute appendicitis diagnosis by ultrarsound
From: https://www.ultrasoundoftheweek.com/uotw-45/

I am so worried. What should I do?

According to the American Academy of Obstetrics and Gynecology, a single diagnostic X-ray exposure is not harmful to the fetus, and even below 50mGy, it is not associated with fetal malformation or miscarriage. This is because the fetal doses rarely exceed 25mGy in general inspections with radiation(even in the abdomen or pelvis). Also abortion is not justified if the fetal dose is less than 100mGy. If it is over 100mGy, it is necessary to judge according to personal situation.

Cf.) In some countries, abortion is considered illegal even if fetal doses exceed 100mGy. This seems to require legal consideration.

To conclude….

Radiation exposure during pregnancy can affect the fetus, but it generally happens at more than 100mGy. Healthy pregnant women usually do not expose to more than 50mGy of fetal radiation in the most of hospital inspections.

It is best not to expose to radiation, but taking a single X-ray or getting a single CT accidentally does not reach a dangerous amount of radiation. If you notice a pregnancy or know that you are pregnant with a urine test, do not worry too much because you are fully being inspected with the consideration of radiation exposure.

A: Don’t worry too much! A single inspection has little effect on the fetus. If you need to take an x-ray while being pregnant, please tell that you are pregnant and we will do our best to reduce radiation!

Reference

1. ICRP, The 1999 Recommendations of the International Commission on Radiological Protection, Ann. ICRP 84, 1999.
2. [Korean] 대한영상의학회. 영상의학 물리학 및 품질관리 제1부. 2012.

Images without source; from Shutterstock.

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