 Is an embryo or fetus adversely affected if a woman undergoes an X-ray examination during pregnancy?
 Malformations or developmental impairment do not occur because of medical irradiation during regular X-ray exams. Abortions sometimes have to be performed on women who had radiological exams when they didn’t know they were pregnant, but effects from normal diagnostic radiology are negligible.
Exposure dose in an embryo during a pregnancy exam using primarily X-rays |
There is no need to worry about malformation in an embryo within the first three weeks after conception. Malformation becomes an issue from the 4th week up to the 7th week, and there is a risk of impaired mental development due to exposure from the 8th week to the 15th week or 25th week. The threshold value for malformations is 100 mGy and for mental and 100 to 200 mGy for motor developmental impairment based on the recommendations of the International Commission on Radiological Protection (ICRP). The ICRP threshold value for malformation is two-fifths of the 250 mGy threshold value set down based on scientific evidence by the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR), and it is considered to be a safe value. The ICRP recommends that exposure of an embryo or fetus to less than 100 mGy should not be considered a reason for undergoing an abortion.
The radiation doses to which embryos or fetuses were exposed in the cases of 50 English women who unknowingly underwent a radiological examination when they were pregnant is shown in the Table. In general, the radiation dose to which the embryo or fetus was exposed did not exceed 100 mGy.
Malformations occur naturally at a fixed rate even in the absence of exposure to medical radiation. Malformations that a layperson would be able to notice occur at a rate of around 7 per 1,000 individuals, and those that can be diagnosed by a physician occur at a rate of 3 to 4 per 100 individuals.
Pediatric cancer is also a problem connected to the exposure of an embryo or fetus to radiation. The ICRP carefully estimates incidence rates when they calculate the radiation exposure risk.
However, the natural incidence rate for pediatric cancer is low at 0.2% to 0.3%, and even if the risk of pediatric cancer rises at the individual level due to exposure of the embryo or fetus to radiation, it is still considered to be low at around 0.3% to 0.4%, even if the embryo or fetus is exposed to 10 mGy.
The reality is that unnecessary abortions are allowed and carried out because women who did not know they were pregnant underwent radiological examinations. Counseling based on accurate data and information is important for a woman who has undergone such a radiological examination. We need to eliminate the tragedy of unnecessary abortions for reasons of radiation exposure.
Table:
Radiation dose to which embryos or fetuses were exposed in the cases of 50 British women who underwent a radiological examination when they did not know they were pregnant
Source:
? ICRP Publication 84, Pregnancy and Medical Radiation, Japan Radioisotope Association
Cheked by Kuniaki Hayashi M.D. Professor Nagasaki University Graduate School of Biomedical Sciences
Cheked by Yutaka Okumura Professor Nagasaki Atomic Bomb Disease Institute Nagasaki University Graduate School of Biomedical Sciences
Written by Hiroyuki Namba M.D. Associate Professor? Nagasaki Atomic Bomb Disease Institute Nagasaki University Graduate School of Biomedical Sciences
Written by Makoto Ochi M.D. Associate Professor Nagasaki University School of Medicine
|
More questions
