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Counseling patients exposed to ionizing radiation during pregnancy
Robert L. Brent'
Suggested citation: Brent RL Counseling patients exposed to ionizing radiation during pregnancy. Rev Panam Salud Publica. 2006;20(2/3);198-204.

SYNOPSIS

Healthphysicists and knowledgeable clinicians have the responsibility to counsel women of reproductive age about the reproductive risks of ionizing radiationexposure before conception or during pregnancy. It is important to realize that lay individuals have many misconceptionsabout the reproductive risks of ionizing radiation.Many patients who have already had or will undergo somc type of radiologicaltest are apprehensive about the reproductive and developmental risks of diagnostic radiologicalprocedures.Epidemiological studies and animal studies indicate that high exposures of ionizing radiationcan cause miscarriage,congenitalmalformations,growth retardation,stillbirth,and cancer. With the exception of cancer, there are threshold exposures for those outcomes, with exposures below certainradiationdoses not increasing the reproductive or developmental risks. The threshold exposure for birth defects at the most sensitive stage of development is 0.2 Gy, and the thresholdfor growth retardationand miscarriage is even higher. However, embryonic loss can occurfrom low exposures during the preimplantationand presomite stages of development ("the all or none period"). This is a stage when theembryo is more likely to die than survive malformed. The most sensitive periodfor the induction of mental retardationis from the 8th week to the 15th week of gestation. The thresholdfor deterministic effects increases after early organogenesis and also as the exposure is protracted, e.g., with radionuclides or multiple radiologicalprocedures.Awareness that the threshold dose for developmentaleffects increases as the fetus develops complicates counseling because we do not have definitive data on threshold exposures at all stages of gestation. Ionizing radiationexposures prior to pregnancy represent a very low riskfor the increased incidence of genetic disease in the offspring of the parents who have had radiationexposures to the ovary or testes. Counseling patients requires knowledge ofembryology, genetics, radiation teratology, and the principles of teratology in orderfor the counselor to provide sympathetic,accurate, scholarly advice.

Health physicists and knowledgeable clinicians

Key words: pregnancy; pregnancy outcome; radiation, ionizing; abnormalities; risk factors; teratogens; counseling.
Thomas Jefferson University, Philadelphia, Pennsylvania, United States ofAmerica, and Alfred I. duPont Hospital for Children, Wilmington, Delaware, United States. Send correspondence to: Robert L Brent, Room 308 R/A, Alfred I. duPont Hospital for Children, Box 269, Wilmington, Delaware 19899, United States; telephone: 302-6516888.

have the responsibility to counsel women of reproductive age about the reproductive risks of ionizing radiation exposure that occurs eitherbefore conception or during pregnancy. Medical personnel need to realize that lay individuals have many misconceptions about the reproductive risks of ionizing radiation. Further, many patients are apprehensive about the reproductive and developmental risks of diagnostic radiological procedures. Counseling patients requires knowledge of embryology, genetics, radiation teratology, and the principlesRep PanamSalud Publica/PanAm I PublicHealth 20(2/3), 2006

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Brent * Counseling patients exposed to ionizing radiation during pregnancy

Articles and special reports

of teratology in order for the counselor to provide sympathetic, accurate, scholarly advice. This paper will help inform medical personnel about the real risks to the embryo from ionizing radiation, provide...