In 1988, when the Atomic Energy Regulatory Board (AERB) held a public awareness programme on diagnostic x-ray examinations for physicians and allied professionals, the topic which received widest attention was “Pregnancy and radiation protection”.
A twenty three year old woman came for discussion. She had three x-ray examinations. She did not know that she was pregnant. Her genetic counsellor recommended abortion as the radiologist could not provide information on the number of “roentgens” the patient received in the examinations. Neither the radiologist nor her “genetic counsellor” attended the programme.
We gave her a paper titled “The Effects of Embryonic and Fetal Exposure to X-Ray, Microwaves and Ultrasound” by Dr. Robert L Brent published in Clinical Obstetrics and Gynecology , June 1983 and some booklets from the International Commission on Radiological Protection (ICRP) and the National Council on Radiation Protection (NCRP) and Measurements. Using the technique factors provided by her radiologist, she calculated her dose to be about 3mSv. She decided not to have an abortion, as the risk, if any, to the embryo was negligible.
Dr Robert Brent, Distinguished Professor of Pediatrics, Radiology and Pathology, Thomas Jefferson University has counselled thousands of pregnant women.
Recently, this writer received from him his exhaustive paper in the January 2009 issue of the American Journal of Obstetrics and Gynecology . Every health professional must read it. It referred to ‘Ask the Expert’ (ATE) section of the American Health Physics Society at:
>http://hps.org/publicinformation/ate/cat4.html
This website provides a few hundred questions and answers related to pregnancy and radiation. You may find that most of your queries are answered. If not, you can send the new query to ATE. Nearly 20 per cent of questions are concerned with the irradiation of testicles and ovary and the effect on fertility and genetic risks to the future offspring. Dr Brent noted that one of the most common questions is how long one has to wait if the sperm or ova have been exposed during a diagnostic radiologic procedure.
“The accepted answer is 2 spermatic cycles for the man and three menstrual cycles for the woman.” Dr Brent revealed. “This is a very conservative approach because the risk of genetic disease after such low exposures is extremely small and there is no increased risk of infertility,” Dr Brent reassured the couples. Two spermatic cycles are covered in four months.
How is the counselling of pregnant women exposed to medical radiation procedures organised and carried out in U.S. hospitals? Responding to this writer's query, Dr Brent stated that there is no national protocol to follow for counselling patients about radiation risks to the foetus. “Health Physicists in Radiology Depts. are the most knowledgeable about these issues and provide the best counselling when asked. Radiologists are less well versed in the matter of risk estimates as your own experience indicates,” Dr Brent wrote.
“I have many contacts from India and I must tell you that a small per cent of Indian counsellors are quick to suggest an abortion without any formal evaluation. You see the number of hits. That is the tip of the iceberg,” Dr Brent revealed. “You began this pregnancy with a 3 per cent risk for birth defects and at the time that you recognised that you are pregnant, you had a 15 per cent risk of miscarriage. Those are average background risks that we cannot change at this time,” Dr Brent cautions. The ICRP booklet titled “Pregnancy and Medical Radiation,” showed that the topic continues to be relevant.
The International Atomic Energy Agency provides instructions on pregnancy and radiation protection in diagnostic radiology, radiotherapy and nuclear medicine at:
>https://rpop.iaea.org/RPOP/RPoP/Content/SpecialGroups/1_PregnantWomen/index.htm>
In the factsheet at the web site of Health Physics Society, Dr Brent states that most diagnostic procedures expose the embryo to less than 50 mSv.
“This level of radiation exposure will not increase reproductive risks (either birth defects or miscarriage). According to published information, the reported dose of radiation to result in an increased incidence of birth defects or miscarriage is above 200 mSv,” Dr Brent assures the readers.
Patients must refer to all resources; they should not blindly follow their genetic counsellors or radiologists.
K.S. PARTHASARATHY,
Former Secretary, Atomic Energy Regulatory Board.
ksparth@yahoo.co.uk
