For the study, the researchers analyzed the results of a survey of 273 family physicians and obstetricians in Ontario. The survey showed that 36% of the doctors estimated the risk of a major fetal malformation from abdominal X-rays to be 5% or greater, and 55% estimated the risk from CT to be 5% or greater. Of the 208 family physicians, 1% recommended abortion if the fetus was exposed to radiation from X-rays, and 6% after exposure to radiation from CT. Of the 65 obstetricians, none recommended an abortion after exposure to radiation from X-rays, but 5% recommended an abortion after exposure to radiation from CT. Overall, a greater percentage of family physicians overestimated the risk as compared to obstetricians.
According to the study, the dosage of radiation, measured in milligrays (mGy), determines whether there is interference with the normal development of a fetus. Adverse fetal affects from radiation exposure include small head, mental retardation, or fatal childhood conditions. The study states that fetal doses exceeding 150 mGy between the second and 15th week of conception may be an indication for abortion; between 50 and 150 mGy may also be an indication, but only if other compromising circumstances exist. However, says the study, most diagnostic imaging examinations, including X-rays and CT, result in less than 50 mGy of radiation exposure to the fetus.
"This misconception is important to dispel because it can lead to increased anxiety among pregnant women inadvertently exposed to diagnostic imaging and unnecessary terminations of otherwise wanted pregnancies. In addition, not having certain types of imaging performed could hinder diagnosis for some illnesses, delaying needed treatment to the patient," said Savithiri Ratnapalan, MD, lead author of the study.
According to Dr. Ratnapalan, education is necessary to correct the misconception concerning the risks of X-rays and CT for women in early pregnancy. "Review articles in general medical journals may be the most practical and efficient way of communicating with a large group of physicians. Discussing radiation doses and effects in seminars and rounds may also be necessary to consolidate the knowledge."
This study appeared in the May 2004 issue of the American Journal of Roentgenology.
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