Pennsylvania Patient Safety Advisory Diagnostic Ionizing Radiation and Pregnancy: Is There a Concern? ABSTRACT sufficient energy to remove an electron from an atom (e.g., gamma rays, x-rays) to form a pair of charged Both pregnant patients and physicians may over- particles (i.e., ions). Lower energy radiation (e.g., estimate the risk of an ionizing diagnostic radiation radio waves, visible light) has insufficient energy examination on the conceptus. Fetal health effects of to cause ionization. The resulting ions can be very ionizing radiation vary according to the radiation dose destructive to biological material since they can break absorbed and gestational phase at the time of expo- chemical bonds. Two types of cell damage occurs; sure. The effects of ionizing radiation are cumulative. the cell can die or be damaged. In the event of cell Performing multiple diagnostic radiation procedures death, the damage to the overall organism will only on a pregnant woman may place the conceptus at risk be significant if a sufficient number of cells are killed. for negative health effects. PA-PSRS has received more Cell death will occur with a sufficient dose. Cell dam- than 90 reports of pregnant patients being exposed age is more complicated. The cell may simply become to diagnostic ionizing radiation since the program’s nonviable and eventually die. Alternatively, the dam- inception in June 2004. Many involved performing a age to the genetic code may be repaired. In the event radiologic procedure on a patient who was unaware that the repair is flawed and the cell remains viable, of the pregnancy. Risk reduction strategies include then mutations may result, eventually manifesting as delaying nonurgent radiographs; using a diagnostic cancer many years later.5,6 Carcinogenesis may or may examination not involving ionizing radiation; ensuring not occur. radiographic equipment is in proper working order; and encouraging open communication among the Measurement healthcare team and patient to ensure that the most appropriate study is used to obtain the maximum Radiation is measured using different terms according amount of information while reducing exposure to the to the aspect of radiation that is being measured. This fetus. (Pa Patient Saf Advis 2008 Mar;5[1]:3-15.) includes exposure, absorbed dose, and effective dose (see Table 1). When measuring radiation exposure, one can directly measure the amount of ionization, which is the number of ions produced in a volume of air. While medical uses of radiation have improved When SI units (metric) are used, exposure is measured diagnostic, treatment, curative, and palliative capa- in coulomb per kilogram (C/kg). In the United States, bilities, radiation may also be damaging or lethal1 exposure is traditionally measured in roentgen (R). to an embryo or fetus in certain circumstances. PA- PSRS has received more than 90 reports of pregnant The biological effects from ionizing radiation depend patients being exposed to diagnostic ionizing radia- upon the total energy of radiation absorbed (in joules) tion (see “Ionizing Radiation Exposures Reported per unit of mass (in kilograms) in the sensitive organs to PA-PSRS”). The PA-PSRS reports show that many or tissues.7,8 This amount is called the absorbed dose. women are not aware they are pregnant during diag- Absorbed dose is expressed in gray (Gy). One gray nostic radiology procedures.2 About 50% of pregnan- equals the absorption of 1 joule of radiation energy cies in North America are unplanned.3 Therefore, the by 1 kg of matter. The gray was adopted interna- possibility of unanticipated radiation exposure to an tionally in 1976.9 Calculation of absorbed doses of embryo/fetus may occur when women of childbearing radiation provides a foundation upon which the age undergo diagnostic radiation procedures. probability of radiation-induced effects can be evalu- This article will present the effects of x-ray radiation, ated. In the United States the absorbed dose is often estimated fetal radiation doses of common diagnostic referred to as radiation absorbed dose (rad). One rad procedures, background incidence of fetal complica- equals 10 mGy.8,9 The absorbed dose is important tions, risk reduction strategies, and resources. The when considering the short term, or deterministic, article will not encompass nuclear medicine proce- effects of radiation. dures, radiation therapy, or occupational exposure to To assess the biological risk of ionizing radiation x-rays. Moreover, in this article, the term “conceptus” after partial exposure of the body, other factors must is used to refer to any stage of conception: pre-embryo, be considered, such as the type of radiation, the embryo, or fetus. varying sensitivity of different tissues, and absorbed doses of different organs.8,9 This risk is expressed What is Ionizing Radiation? as the effective dose. The metric unit is the sievert Radiation is energy that is emitted from sources4 (Sv). Traditionally in the United States, the roentgen including heat and light from the sun, microwaves equivalent man (rem) is used instead of the sievert. from an oven, or x-rays from an x-ray tube. The charac- One Sv equals 100 rem.8,9 The effective dose is used teristics of the radiation depend on its energy. Ioniza- to assess the long-term, or stochastic, risks associated tion refers to the process in which the radiation has with radiation exposure. Vol. 5, No. 1—March 2008 REPRINTED ARTICLE - ©2008 Pennsylvania Patient Safety Authority Page 3 Pennsylvania Patient Safety Advisory Ionizing Radiation Exposures Reported to PA-PSRS PA-PSRS has received more than 90 reports of ultrasound showed a viable intrauterine preg- pregnant patients being exposed to diagnostic ion- nancy of seven weeks and one day. izing radiation. Here are a few edited examples: The patient had a CT scan of the abdomen A patient was asked if she could be pregnant and pelvis, and the radiologist’s interpretation and the date of her last menstrual period. The revealed a fetus. patient responded that she receives contracep- A patient presented to the ED with fever and tion injections and does not get periods. The abdominal pain. The patient had a history of patient signed a release indicating she was not [inflammatory bowel disease] and tubal liga- pregnant. An x-ray of the abdomen was per- tion three years ago. The patient also reported formed, which revealed a fetus. her last menstrual period was within the past month. The patient had a CT scan of the abdo- A patient presented to the [emergency depart- men, which revealed an intrauterine pregnancy. ment (ED)] with a chief complaint of back pain. Upon notification, the patient stated she had She was asked if she was pregnant, and she been at another hospital the previous week stated no. X-ray films were read, revealing a and had an x-ray of the abdomen. The patient fetus of over 31 weeks. The patient was notified was seen by an obstetrician, and an ultrasound of the pregnancy, at which time she stated her was performed, indicating an intrauterine preg- last menstrual period was seven months ago. nancy of 15 weeks gestation. A patient was scheduled for a [computed A patient was sent to the imaging department tomography (CT) scan] of the abdomen and for a CT scan due to abdomen/pelvis bloating. pelvis to rule out a mass. The patient was She responded “no” when asked if there was a interviewed and signed a form indicating she chance she could be pregnant, and she signed was not pregnant. The patient stated she had the consent form. The CT scan revealed an a negative pregnancy test 10 days ago. The intrauterine pregnancy. CT study was performed with contrast. The scan was aborted as soon as an image of fetus An ED patient [underwent] an x-ray of the abdo- appeared. men. The patient had not voided prior to the x-ray, but the patient stated, when asked by the A patient received a CT scan of the abdomen ED staff and the x-ray technician, that she had and pelvis in 60 slices. Prior to the procedure, a period two weeks earlier and that she felt she she stated she did not believe she could be was not pregnant. After the x-ray, the patient pregnant. The CT scan showed a viable fetus voided, and the dipstick was positive for preg- of 12 weeks gestation. nancy. A follow-up ultrasound indicated twins. Over a seven-week period of time, a 19-year- An ED patient denied the possibility of preg- old patient received the following studies: nancy and stated she had a miscarriage one abdomen x-ray, CT scan of the abdomen and month prior to admission. An abdominal CT pelvis with and without contrast, retrograde scan was done, after which a urine specimen x-ray, chest x-ray, and cystogram. For each was obtained that was positive for pregnancy. visit, the patient was asked if she was or could A transvaginal ultrasound confirmed an intra- be pregnant, and she denied pregnancy each uterine pregnancy. The patient is planning to time. At the end of the seven weeks, an terminate the pregnancy. This article will refer to mGy and rad as units of mea- major malformations after exposure to diagnostic sure (10 mGy = 1 rad). imaging.11 Twenty-three percent of pregnancies in Greece were terminated because of unfounded Perceptions concerns about fetal teratogenicity after the nuclear When a pregnant patient is exposed to radiation reactor accident in Chernobyl.12 during diagnostic radiology procedures, lack of knowl- In Canada, the Motherisk Program conducted a survey edge may result in great anxiety after exposure and of pregnant women who were told that the baseline misinterpretation of the risk.10 A woman may believe risk of major malformations in the general population she should abort her fetus after any exposure to ion- was about 3%. They were asked their perceptions of izing radiation.7 One study revealed that up to 25% of risk for fetal malformations when a pregnant woman exposed women believed their infants were at risk for underwent a diagnostic imaging procedure. The Table 1. Measurement of Radiation QUANTITY METRIC (SI) CONVENTIONAL CONVERSION COMMENT Exposure Coulomb per kilogram Roentgen (R ) 1 R = 2.58 × 10-4 C/kg Directly measured (C/kg) Absorbed dose Gray (Gy) Radiation absorbed dose (rad) 10 mGy = 1 rad Deterministic effects Effective dose Sievert (Sv) Roentgen equivalent man (rem) 1 Sv = 100 rem Stochastic effects Page 4 REPRINTED ARTICLE - ©2008 Pennsylvania Patient Safety Authority Vol. 5, No. 1—March 2008 Pennsylvania Patient Safety Advisory pregnant women who had been actually exposed to a at six weeks gestation: (1) radiograph (kidneys, ureters, diagnostic imaging procedure estimated the teratogenic bladder) and (2) abdominal CT scan. risk as 25.5%. The nonexposed pregnant control More than 30% of the responding facility practitioners group perceived the risk as 15.7%.13 This fear of radia- and 20% of the responding obstetricians would have tion and misinterpretation of the effect on the fetus overestimated the risk of major malformations as a may persist even when evidence-based data of the result of this radiation exposure.13 The physicians’ safety of low-dose radiation exposure is provided.10 misperceptions might have produced increased anxi- Physicians may also overestimate this risk. One study13 ety among women seeking counseling, unnecessary indicated that physicians caring for pregnant women pregnancy terminations, and/or delays in necessary have unrealistically high perceptions of the teratogenic diagnostic procedures for pregnant women.13 risk associated with abdominal radiographs/computed tomography (CT) scans administered during early Risks in the General Population pregnancy. This misperception might result in delay In order to understand the risks to the conceptus asso- of necessary diagnostic procedures or inappropriate ciated with exposure to diagnostic x-rays, one needs medical advice resulting in unnecessary termination of to understand the risks to the conceptus without pregnancy.14 exposure to diagnostic radiation. It is also important A survey of family physicians and obstetricians in Israel to know the conceptus usually receives less that 1 mGy revealed that 40% of responding family physicians and (0.1 rad) of natural background radiation during a 70% of obstetricians recommended therapeutic abor- nine-month gestation.2 This background radiation is tion for women exposed to radiation from a diagnostic from four major sources: cosmic radiation, solar radia- imaging procedure in early pregnancy.13 In another sur- tion, external terrestrial sources (e.g., rocks, soil), and vey in Ontario, Canada, of randomly selected family radon gas.4 Table 2 specifies the incidence of the risks practitioners and obstetricians, the respondents were to the fetus associated with pregnancy without acute informed of the baseline risk of major fetal malforma- radiation exposure. The general population’s total tions (1% to 3%) without medical diagnostic imaging. risk of spontaneous abortion, major malformations, They were asked about their perceptions of fetal risk mental retardation, and childhood malignancy is associated with the following two imaging procedures approximately 28.6% (286 per 1,000 deliveries).6 Table 2. Background Incidence of Conceptus Complications without Diagnostic Imaging Radiation RISKS INCIDENCE Spontaneous incidence of major malformations Approximately 1% to 3% Intrauterine growth restriction 4% Spontaneous abortion At least 15% Genetic disease 8% to 10% Mental retardation (intelligence quotient less than 70) Approximately 3% Severe mental retardation (unable to care for self) 0.5% Heritable effects 1% to 6% Spontaneous risk of childhood leukemia and cancer (ages 0 to 15) 0.16% Children developing cancer up to age 15 (United Kingdom) 0.15% Children developing leukemia only to age 15 (United Kingdom) 0.03% Lifetime risk of contracting cancer 33% Lifetime risk of contracting fatal cancer 20% Sources: ACOG Committee on Obstetric Practice. ACOG Committee Opinion. Number 299, September 2004 (replaces No. 158, September 1995). Guidelines for diagnostic imaging during pregnancy. Obstet Gynecol 2004 Sep;104(3):647-51; Brent RL. The effects of embryonic and fetal exposure to x-ray, microwaves, and ultrasound. In: Brent RL, Beckman DA, editors. Clinics of perinatology, teratology. Vol 13. Philadelphia (PA): Saunders;1986:613-48; Coakley F, Gould R. Guidelines for the use of CT and MRI during pregnancy and lactation. Chapter 5. In: UCSF imaging of retained surgical objects in the abdomen and pelvis section handbook [online]. University of California, San Francisco Department of Radiology. 2005 [cited 2007 Jun 6]. Available from Internet: http://www.radiology.ucsf.edu/instruction/abdominal/ab_handbook/05-CT_MRI_preg.html; Harding LK, Thomson WH. Radiation and pregnancy. Q J Nucl Med 2000 Dec;44(4):317-24; International Commission on Radiological Protection. Radiation and your patient: a guide for medical practitioners. Ann IRCP 2001;31(4):5-31; International Commission on Radiological Protection (ICRP). Biological effects after prenatal irradiation (embryo and fetus). ICRP Publication No. 90. Kidlington, Oxford (United Kingdom): Elsevier; 2003; International Commission on Radiological Protection (ICRP). Pregnancy and medical radiation. ICRP Publication No. 84. Kidlington, Oxford (United Kingdom): Elsevier; 2000; Ratnapalan S, Bona N, Chandra K, et al. Physician’s perceptions of teratogenic risk associated with radiography and CT during early pregnancy. AJR Am J Roentgenol 2004 May;182(5):1107-9; Ratnapalan S, Bona N, Koren G. Ionizing radiation during pregnancy. Can Fam Physician 2003 Jul;49:873-4; Sharp C, Shrimpton JA, Bury RF. Diagnostic medical exposures: advice on exposure to ionizing radiation during pregnancy [online]. Chilton, Didcot, Oxon (UK): National Radiological Protection Board. 1998 [cited 2007 Jul 19]. Available from Internet: http://www.e-radiography.net/regsetc/nrpb_asp8/Diagnostic Medical Exposures Advice on Exposure to Ionising Radiation during Pregnancy.htm; Timins JK. Radiation during pregnancy. N J Med 2001 Jun;98(6):29-33; Toppenberg KS, Hill DA, Miller DP Safety of radiographic imaging during . pregnancy. Am Fam Physician [online]. 1999 Apr 1 [cited 2008 Jan 21]. Available from Internet: http://www.aafp.org/afp/990401ap/1813.html. For sources associated with specific values, contact the Pennsylvania Patient Safety Advisory staff. Vol. 5, No. 1—March 2008 REPRINTED ARTICLE - ©2008 Pennsylvania Patient Safety Authority Page 5 Pennsylvania Patient Safety Advisory Approximate Fetal Radiation Doses of presents the approximate fetal doses of common Common Diagnostic Procedures diagnostic procedure using ionizing radiation.) These estimated fetal doses, however, could vary by a factor The majority of diagnostic procedures provide a of 10 to 100 for the same study, based on the tech- fetal dose much less than 50 mGy (5 rad).15 (Table 3 niques and equipment used.1,7,15,16 Variables include Table 3. Approximate Fetal Radiation Doses of Common Diagnostic Procedures PROCEDURE mSv MEAN DOSE mGy (rad)* MAXIMUM DOSE mGy (rad)* X-ray Abdomen 1 1.4 (0.14) 4 (0.4) Kidney, ureter, and bladder 1.7 2.9 (0.29) 15 (1.5) Chest 0.02 less than 0.01 (0.001) less than 0.01 (0.001) Intravenous urogram/ 10 to 20 1.7 (0.17) 10 (1); pyelogram 0.37 to 2.64 (0.037 to 0.264) Lumbar spine 1.3 1.7 (0.17); 10 (1) 0.9 (0.09) Pelvis 0.7 1.1(0.11); 4 (0.4); 3.4 (0.34) 22 (2.2) Skull 0.07 less than 0.01(0.001); less than 0.01 (0.001) 0.04 (0.004) Thoracic spine 0.7 less than 0.01 (0.001) less than 0.01 (0.001); 0.03 (0.003) Dental less than 0.001 (0.0001); less than 0.01 (0.001) Upper/lower extremity less than 0.01 0.01 (0.001) Mammogram 0.6 less than 0.05 (0.005) 0.2 (0.02) Hip 0.3 0.51 to 1.40 (0.051 to 0.14) Computed Tomography Abdomen 10 8 (0.8); 49 (4.9); 7.6 (0.76) 26 (2.6) Chest 8 0.06 (0.006) 0.96 (0.096); less than 1 (0.1) Hand less than 0.005 (0.0005) less than 0.005 (0.0005) Lumbar spine 2.4 (0.24); 8.6 (0.86); 7.50 (0.75) 40 (4) Pelvis** 7.1 25 (2.5) 79 (7.9) Head 2.3 less than 0.005 (0.0005) less than 0.005 (0.0005) Pelvimetry 0.2 (0.02) 0.4 (0.04) Fluoroscopy Upper GI 1.1 (0.11) 5.8 (0.58); 0.56 (0.056) Barium enema** 7 6.8 (0.68); 24 (2.4); 10 (1) 130 (13) Barium swallow 15 1.1 (0.11) 5.8 (0.58) * Duplicate values represent different estimations in the literature. ** Highlighted rows indicate potential exposures of more than 50 mGy. Sources: Centers for Disease Control and Prevention. Prenatal radiation exposure: a fact sheet for physicians. [emergency preparedness & response fact sheet online]. 2005 Mar 23 [cited 2008 Jan 21]. Available from Internet: http://www.bt.cdc.gov/radiation/prenatalphysician.asp; Cohen-Kerem R, Nulman I, Abramow-Newerly M, et al. Diagnostic radiation in pregnancy: perception versus true risks. J Obstet Gynaecol Can 2006 Jan;28(1):43-8; De Santis M, Di Gianantonio E, Straface G, et al. Ionizing radiation in pregnancy and teratogenesis: a review of literature. Reprod Toxicol 2005 Sep-Oct;20(3):323-9; Hamilton PM, Roney PL, Keppel KG, et al. Radiation procedures performed on U.S. women during pregnancy: findings from two 1980 surveys. Public Health Rep 1984 Mar-Apr;99(2):146-51; International Atomic Energy Agency. Radiologic protection of patients: pregnancy and radiation in diagnostic radiology. [online]. [cited 2008 Jan 21]. Available from Internet: http://rpop.iaea. org/RPoP/RPoP/Content/SpecialGroups/1_PregnantWomen/PregnancyAndRadiology.htm; International Commission on Radiological Protection. Radiation and your patient: a guide for medical practitioners. Ann IRCP 2001; International Commission on Radiological Protection (ICRP). Biological effects after prenatal irradiation (embryo and fetus). ICRP Publication No. 90. Kidlington, Oxford (United Kingdom): Elsevier; 2003; International Commission on Radiological Protection (ICRP). Pregnancy and medical radiation. ICRP Publication No. 84. Stockholm (Sweden): ICRP; 2000; Ionizing radiation during pregnancy [online]. 2003 Nov 5 [cited 2006 Sep 7]. Available from Internet: http://www.perinatology. com/exposures/Physical/Xray.htm; Kusama T, Ota K. Radiological protection for diagnostic examination of pregnant women. Congenit Anom (Kyoto) 2002 Mar;42(1):10-14; Lockwood D, Einstein D, Davros W. Diagnostic imaging: radiation dose and patients’ concerns. Cleve Clin J Med 2006 Jun;73(6):583-6; Ratnapalan S, Bona N, Koren G. Ionizing radiation during pregnancy. Can Fam Physician 2003 Jul;49:873-4; Sharp C, Shrimpton JA, Bury RF. Diagnostic medical exposures: advice on exposure to ionizing radiation during pregnancy [online]. Chilton, Didcot, Oxon (UK): National Radiological Protection Board. 1998 [cited 2007 Jul 19]. Available from Internet: http://www.e-radiography.net/regsetc/ nrpb_asp8/Diagnostic Medical Exposures Advice on Exposure to Ionising Radiation during Pregnancy.htm; Smits AK, Paladine HL, Judkins DZ, et al. Clinical inquiries. What are the risks to the fetus associated with diagnostic radiation exposure during pregnancy? J Fam Pract 2006 May;55(5):441-2,444; Timins JK. Radiation during pregnancy. N J Med 2001 Jun;98(6):29-33. For sources associated with specific values, contact the Pennsylvania Patient Safety Advisory staff. Page 6 REPRINTED ARTICLE - ©2008 Pennsylvania Patient Safety Authority Vol. 5, No. 1—March 2008 Pennsylvania Patient Safety Advisory filtration, presence of a grid, and x-ray parameters. Effects According to Stages of Pregnancy Moreover, in fluoroscopy-based exams, fetal doses are During the entire gestation, mammalian embryos difficult to calculate because it may be unknown how and fetuses are radiosensitive. The type and severity long the conceptus is actually in the primary beam, of most induced biological effects depend on the which the radiologist may move during the procedure. developmental stage of the conceptus during which Additional factors affecting fluoroscopy doses include radiation exposure occurs.21 Most of the effects of magnification, grid use, and whether conventional ionizing radiation can be considered according to or pulse fluoroscopy is used. Fetal dose is also greatly the following stages of pregnancy: pre-implantation, affected by such patient anatomical factors as thick- organogenesis, and fetal development. ness of the patient, anteversion or retroversion of the uterus, and distension of the bladder.1 Pre-implantation. The pre-implantation stage begins from the moment the egg is fertilized until the fertil- Effects of Ionizing Radiation ized egg attaches to the uterine wall (zero to two weeks postconception).22 Because chemicals and drugs are metabolized and transported through the placenta to the conceptus, Organogenesis (embryonic). During the organogen- there can be variations in how they affect different esis stage (two weeks postconception until seven to mammalian species. However, ionizing radiation eight weeks postconception), cell migration of multi- affects the conceptus directly. As a result, the effect of potential progenitor cells forms the major organs.22 ionizing radiation in studies using animal models is more directly applicable to humans.10 Fetal development. In the fetal development stage (eight or nine weeks to delivery), differentiated organs General Effects undergo cellular growth. The three phases are as fol- Ionizing radiation passing through living matter pro- lows: early, mid, and late.22 duces physical and chemical changes at various levels: Table 4 presents possible health effects to the con- molecular, cellular, tissue, and the whole organism.16 ceptus, according to radiation dose and stage of Two types of effects can be produced by ionizing radi- pregnancy. ation: deterministic effects and stochastic effects.7,15,17 (Refer to Table 1.) Severe mental retardation. While most major organs form and differentiate during the organogenesis phase Deterministic. These effects occur above a certain of pregnancy, the CNS continues to differentiate dur- threshold dose of ionizing radiation.7,15,17 Below this ing the organogenesis, early fetal, and mid-fetal stages threshold, the effects in exposed populations are of pregnancy.22 The risk of severe mental retardation similar to control populations who have received varies with the stage of pregnancy. Table 5 displays only background radiation.4 Deterministic effects the variations in this risk to the conceptus during are caused by cell killing, and the severity of the gestation. During early fetal development (8 to 15 effect increases as the dose above the threshold weeks), 50 mGy is associated with IQ reduction.23 increases.7,18,19 Cell killing can produce death; growth This dose can be reached by a single CT scan of the retardation; abnormal brain/central nervous system abdomen and pelvis or by a barium enema (refer to (CNS) development, including mental retardation Table 3). and behavioral disorders; abortion; malformation; and cataracts.16,19 Carcinogenicity (radiation-induced cancer and leukemia). Radiation has been shown to cause many Stochastic. Stochastic effects can occur after any types of cancer and leukemia in adults and chil- exposure and involve damage to the nuclear material dren.1,24 However, the estimates of cancer risk related in cells, causing hereditary mutations or radiation- to diagnostic radiation vary considerably. Therefore, induced cancer including leukemia.8,15-17 For such the risk of diagnostic-radiation-induced cancer and DNA damage or misrepair, there is no threshold dose leukemia remains unclear. More recent, well-designed below which the chance of these effects is zero.7,17,19 studies do not replicate an association between child- Stochastic effects also increase with radiation dose. hood malignancies and in utero diagnostic radiation Effects on the Conceptus exposure found in earlier studies.2,25 A recent analysis (ICRP 90) concludes that the relative risk of child- Ionizing radiation can produce the following effects hood cancer is 1.37 per 10 mGy (1 rad) of exposure.21 on the conceptus, which depend upon the fetal dose absorbed and the phase of gestation at the time expo- Genetic/mutation/heritable effects (alteration of sure occurs.18,20 Exposing a fetus to 5 mGy (0.5 rad) germ cell lines). Radiation increases the frequency of adds about 0.17 cases per 1,000 deliveries (or about 1 mutations above mutations naturally occurring in the case per 6,000 deliveries) to the general population’s general population. However, no radiation-induced risks of spontaneous abortion, major malformation, gene mutations have been demonstrated unequivo- mental retardation, and childhood malignancy.7 cally in humans when the conceptus is exposed to Harmful effects can be categorized as follows: cell/ diagnostic radiation.20 Therefore, the exposure risk is intrauterine death, teratogenicity, carcinogenicity, and considered to be the same as the risk after birth, 1 in genetic/mutation/heritable effects.14,20 4,200 per 10 mGy (1 rad), compared to the estimated Vol. 5, No. 1—March 2008 REPRINTED ARTICLE - ©2008 Pennsylvania Patient Safety Authority Page 7 Pennsylvania Patient Safety Advisory Table 4. Effects of Ionizing Radiation on Conceptus PREGNANCY WEEKS POST PHASE CONCEPTION RADIATION EXPOSURE POSSIBLE CONCEPTUS HEALTH EFFECTS Pre-implantation 0 to 2 weeks Diagnostic exposure (less Embryo implantation failure; embryo death by than 100 mGy [10 rad]) cytogenic damage Greater than 100 mGy Lethality (10 rad) Organogenesis 2 to 7/8 weeks Less than 50 mGy (5 rad) No increase of significant congenital malformations above background incidence Greater than 100 mGy to Malformations due to cell killing; growth retardation; 150 mGy (10 rad to 15 rad) cataracts; skeletal anomalies; central nervous system abnormalities: microcephaly, mental retardation (risk of severe mental retardation is not increased over background levels) Fetal Development Early 8/9 weeks to Less than 50 mGy (5 rad) Cancer is the only detectable health risk 15 weeks 50 mGy to 500 mGy (5 rad Dose dependent growth retardation; IQ reduction to 50 rad) Greater than 500 mGy Increased risk of growth retardation/spontaneous (50 rad) abortion; major malformation; IQ reduction; severe mental retardation Mid 16 weeks to Less than 50 mGy (5 rad) Cancer is the only detectable health risk 25 weeks 50 mGy to 500 mGy (5 rad Not likely to produce health risk except cancer to 50 rad) Greater than 500 mGy Increase in major malformations and spontaneous (50 rad) abortions; dose dependent growth retardation; IQ reduction; severe mental retardation Late 26 weeks to Less than 500 mGy (50 rad) Cancer is the only detectable health risk delivery Greater than 500 mGy Dose dependent neonatal death and spontaneous (50 rad) abortion; major functional anomalies or malformations unlikely Sources: Centers for Disease Control and Prevention. Prenatal radiation exposure: a fact sheet for physicians. [emergency preparedness & response fact sheet online]. 2005 Mar 23 [cited 2008 Jan 21]. Available from Internet: http://www.bt.cdc.gov/radiation/prenatalphysician. asp; De Santis M, Di Gianantonio E, Straface G, et al. Ionizing radiation in pregnancy and teratogenesis: a review of literature. Reprod Toxicol 2005 Sep-Oct;20(3):323-9; International Atomic Energy Agency. Radiologic protection of patients: pregnancy and radiation in diagnostic radiology. [online]. [cited 2008 Jan 21]. Available from Internet: http://rpop.iaea.org/RPoP/RPoP/Content/SpecialGroups/1_PregnantWomen/ PregnancyAndRadiology.htm; International Commission on Radiological Protection. Radiation and your patient: a guide for medical practitioners. Ann IRCP 2001;31(4):5-31; International Commission on Radiological Protection (ICRP). Biological effects after prenatal irradiation (embryo and fetus). ICRP Publication No. 90. Kidlington, Oxford (United Kingdom): Elsevier; 2003; Lowe SA. Diagnostic radiography in pregnancy: risks and reality. Aust N Z J Obstet Gynaecol 2004 Jun;44(3):191-6; Timins JK. Radiation during pregnancy. N J Med 2001 Jun;98(6):29-33; Toppenberg KS, Hill DA, Miller DP Safety of radiographic imaging during pregnancy. Am Fam Physician [online]. 1999 Apr 1 [cited 2008 Jan 21]. Available from . Internet: http://www.aafp.org/afp/990401ap/1813.html. For sources associated with specific values, contact the Pennsylvania Patient Safety Advisory staff. background frequency of genetic mutation and heri- Justification table (refer to Table 2).19,21 The physician justifies each use of medical radiation Low-dose radiation exposure. While low-dose diag- during pregnancy—the benefits must outweigh the nostic radiation is generally considered not harmful risks.1,6,7,16,17,26 Whenever possible, both parents are to the conceptus, some studies have indicated certain included in this decision-making process.6 There are, problems (refer to Table 6). Many of these studies have of course, two individuals involved in this evaluation.1 been criticized because of failure to control certain While the mother may receive direct benefit from the variables, the need to use retrospective methodology, diagnostic procedure, her fetus may be exposed without study size, and/or lack of biological plausibility.26 direct benefit. But, if the mother’s medical problem is serious, diagnostic radiation may lead to lifesaving Risk Reduction Strategies medical interventions that may directly benefit the Because some of the effects of ionizing radiation are fetus.1 Another consideration is determining whether cumulative, performing multiple diagnostic radiation the diagnostic procedure is useful—will its outcome procedures on a pregnant woman may place the con- strengthen confidence in the diagnosis and influence ceptus at risk. Several strategies can be used to reduce patient intervention.7 The physician balances the this risk. medical needs against potential radiation risks on a Page 8 REPRINTED ARTICLE - ©2008 Pennsylvania Patient Safety Authority Vol. 5, No. 1—March 2008 Pennsylvania Patient Safety Advisory Table 5. Fetal Effects of Ionizing Radiation: Severe Mental Retardation PREGNANCY WEEKS POST PHASE CONCEPTION RADIATION EXPOSURE RISK OF MENTAL RETARDATION Organogenesis 2 to 8 weeks Diagnostic radiation No increased risk 100 mGy to 200 mGy Mental retardation (10 rad to 20 rad) 1,000 mGy (100 rad) Reduction of IQ (25 to 30 points); severe mental retardation in 40% of cases 1,500 mGy (150 rad) Severe mental retardation in 60% of cases Fetal development Early 8/9 to 15 weeks Diagnostic radiation No increased risk 200 mGy (20 rad) Malformation of forebrain producing mental retardation 1,000 mGy (100 rad) Reduction of IQ (25 to 30 points); severe mental retardation in 40% of cases 1,500 mGy (150 rad) Severe mental retardation in 60% of cases Mid 16 to 25 weeks Diagnostic radiation No increased risk Above diagnostic radiation Less risk of IQ reduction and severe mental retardation Late 26 to delivery Central nervous system is relatively radioresistent Sources: ACOG Committee on Obstetric Practice. ACOG Committee Opinion. Number 299, September 2004 (replaces No. 158, September 1995). Guidelines for diagnostic imaging during pregnancy. Obstet Gynecol 2004 Sep;104(3):647-51; De Santis M, Di Gianantonio E, Straface G, et al. Ionizing radiation in pregnancy and teratogenesis: a review of literature. Reprod Toxicol 2005 Sep-Oct;20(3):323-9; Harding LK, Thomson WH. Radiation and pregnancy. Q J Nucl Med 2000 Dec;44(4):317-24; Henshaw SK. Unintended pregnancy in the United States. Fam Plann Perspect 1998 Jan-Feb;30(1):24-9, 46; International Atomic Energy Agency. Radiologic protection of patients: pregnancy and radiation in diagnostic radiology. [online]. [cited 2008 Jan 21]. Available from Internet: http://rpop.iaea.org/RPoP/RPoP/Content/SpecialGroups/1_ PregnantWomen/PregnancyAndRadiology.htm; International Commission on Radiological Protection. Radiation and your patient: a guide for medical practitioners. Ann IRCP 2001;31(4):5-31; International Commission on Radiological Protection (ICRP). Biological effects after prenatal irradiation (embryo and fetus). ICRP Publication No. 90. Kidlington, Oxford (United Kingdom): Elsevier; 2003; International Commission on Radiological Protection (ICRP). Pregnancy and medical radiation. ICRP Publication No. 84. Kidlington, Oxford (United Kingdom): Elsevier; 2000; Timins JK. Radiation during pregnancy. N J Med 2001 Jun;98(6):29-33; Toppenberg KS, Hill DA, Miller DP Safety of radiographic imaging during . pregnancy. Am Fam Physician [online]. 1999 Apr 1 [cited 2008 Jan 21]. Available from Internet: http://www.aafp.org/afp/990401ap/1813.html. For sources associated with specific values, contact the Pennsylvania Patient Safety Advisory staff. case-by-case basis, rather than solely on numerical cal- repeat studies are necessary if such studies were recently culations.1 Radiographs that are ordered will ideally not performed at another hospital or outpatient setting.7 only meet the criterion of medical necessity but also be The following diagnostic studies may be medically in accordance with appropriate published guidelines.6,7 unjustified during pregnancy:7 Usually, the risk of not making a correct diagnosis is greater than the radiation risk involved.7,27 If the ■ Lower lumbosacral radiographs in patients with mother’s condition requires x-rays, there usually stable degenerative conditions of the spine should be no hesitation in ordering a needed study.6 ■ Routine chest x-rays at hospital admission or Delay before surgery in the absence of cardiac or pulmo- If radiographic information is not likely to alter nary disease/insufficiency immediate medical management, it may be prudent The World Health Organization concluded that rou- to delay nonurgent radiographs, particularly during tine screening chest x-rays during pregnancy are not the sensitive CNS period of early fetal development indicated unless there is a high incidence locally of from 8 to 15 weeks after conception.6 Any delay until clinically silent chest disease.1 CT of the fetus should after pregnancy must be considered in light of the be avoided in all trimesters of pregnancy.30 clinical status of the mother and unborn child, bal- Moreover, x-ray pelvimetry is of limited medical value ancing the risks and benefits to both.7,17 and should not be performed on a routine basis.1 Because of some studies linking maternal, prenatal There is a poor statistical correlation between pelvic dental x-rays with low-birth-weight babies, the Ameri- measurements and the course of labor. If x-ray pelvi- can Dental Society recommends that pregnant women metry is medically necessary, the reasons should be postpone elective dental x-rays until after delivery.28 clearly documented.1 Avoidance Alternatives Avoid studies in pregnant patients that do not influ- If a patient is pregnant, consider whether another ence patient care.29 Moreover, consider whether diagnostic examination can be substituted.18,20 Ultra- follow-up diagnostic studies involving ionizing radia- sound and magnetic resonance imaging (MRI) have tion are medically necessary.29 Also, consider whether no known risks to a developing fetus and do not Vol. 5, No. 1—March 2008 REPRINTED ARTICLE - ©2008 Pennsylvania Patient Safety Authority Page 9 Pennsylvania Patient Safety Advisory Table 6. Fetal Effect of Low-Dose Diagnostic Ionizing Radiation Exposure STUDY RADIATION DOSE FETAL HEALTH EFFECT Jacobson and Mellemgaard Low dose Eye anomalies Kinlen and Acheson Low dose No increased rate of malformations or spontaneous abortions Bohnen et al. Diagnostic radiation of greater than 0.3 rad during Significant reduction of infant head second or third trimester circumference Diagnostic radiation of greater than 0.3 rad during No effect first trimester Hamilton et al. Diagnostic radiation Lower birth weight babies Hujoel et al. Dental radiographs during pregnancy (threshold Increased risk of low birth weight babies dose 0.4 mGy [0.04 rad]) Boice et al., De Santis et al. Diagnostic radiation with thyroid exposure during Slight reduction of birth weight first trimester (threshold dose 0.4 mGy to 0.9 mGy [0.04 rad to 0.08 rad]) Sources: Bohnen NI, Ragozzino MW, Kurland LT. Brief communication: effects of diagnostic irradiation during pregnancy on head circumference at birth. Int J Neurosci 1996 Nov;87(3-4):175-80; Boice JD Jr, Stovall M, Mulvihill JJ, et al. Dental x-rays and low birth weight. J Radiol Prot 2004 Sep;24(3):321-3; De Santis M, Straface G, Cavaliere AF, et al. First trimester maternal thyroid X-ray exposure and neonatal birth weight. Reprod Toxicol 2005 May-Jun;20(1):3-4; Hamilton PM, Roney PL, Keppel KG, et al. Radiation procedures performed on U.S. women during pregnancy: findings from two 1980 surveys. Public Health Rep 1984 Mar-Apr;99(2):146-51; Hujoel PP Bollen AM, Noonan CJ, et al. Antepartum dental , radiography and infant low birth weight. JAMA 2004 Apr 24;291(16):1987-93; Jacobsen L, Mellemgaard L. Anomalies of the eyes in descendents of women irradiated with small X-ray doses during age of fertility. Acta Ophthalmol (Copenh) 1968;46(3):352-4; Kinlen LJ, Acheson ED. Diagnostic irradiation, congenital malformations and spontaneous abortion. Br J Radiol 1968 Sep;41(489):648-54. involve ionizing radiation.7,16,18,20,24 In certain circum- area of interest, shielding the x-ray equipment and fetus stances, direct visualization of the mother’s pathology when possible, increasing kVp, removing the antiscat- (e.g., using endoscopy or laryngoscopy) may promote ter grid, and taking fewer films.1,18 accurate diagnosis.29 Diagnostic alternatives may be appropriate when cost, waiting time, or organizational If fluoroscopy is required, it should be used sparingly difficulties are not prohibitive.7 and judiciously to reduce the time of fetal exposure, as fetal doses can exceed 50 mGy (5 rad), especially For example, if pelvimetry must be done, the obstetri- if fluoroscopy time exceeds seven minutes.1,7,27 Both cian can obtain adequate information by ultrasound shorter beam time and greater distance to the patient or MRI, thus avoiding ionizing radiation.1,30 For acute can reduce the radiation dose.27 appendicitis during the first and second trimester, MRI and/or ultrasound can be considered instead of If CT of the abdomen or pelvis is absolutely neces- obtaining a CT scan.30 Ultrasound is the initial study sary, consider single, low-dose CT scan.29 Techniques of choice to identify renal calculi.30 For trauma, ultra- that may reduce dose during CT scans in general sound may be sufficient, but CT may be necessary if include establishing the optimal electrical current specific anatomic injuries are suspected.30 (mAs) through the x-ray tube, scanning only the area necessary, using multiple phase scanning only if Optimization/Minimization/Protection needed, and using organ shielding that is designed When a pregnant patient requires x-ray, the examina- for CT scans.31 Radiation reduction techniques may tion should be optimized to provide good diagnostic be used as long as they do not unduly reduce the quality for the least possible exposure to the fetus.1,18 diagnostic value of the x-ray examination.1 Tailoring Medically necessary radiography or fluoroscopy of each examination and reviewing each radiograph as areas remote from the fetus (e.g., head, chest, extremi- it is taken until a diagnosis can be achieved, then ties) can be safety performed at any time during the terminating the procedure, will reduce radiation pregnancy if x-ray equipment is shielded properly, exposure.27 Examples include using low-dose CT to x-ray beam collimation is used, proper technique/pro- perform medically necessary pelvimetry. Conven- cedures are followed, and the equipment is in proper tional excretory urography will most likely involve working order.1,7,24 lower radiation than CT urography.29 If pulmonary embolism is suspected, a CT pulmonary angiogram When a pregnant woman requires medically necessary exposes the fetus to less radiation than a VQ (pulmo- abdominal or pelvic diagnostic x-ray examinations in nary ventilation/quantification) scan.30 which the x-ray beam directly irradiates the fetus, fetal exposure can be reduced while obtaining required diag- Lead shielding of the abdomen and pelvis will reduce nostic information.7,17,25 The following techniques can radiation exposure to the fetus,29 but only slightly, reduce radiation for all modes of diagnostic radiology since some exposure comes from internal scatter. The procedures: increasing filtration, decreasing electri- American Dental Society recommends that if a preg- cal current (mAs), and increasing kVp. Additionally, nant woman’s dental x-rays cannot be delayed until for x-rays, techniques that reduce ionizing radiation after delivery, abdominal shielding and a protective include collimation of the x-ray beam to a very specific thyroid collar be applied during the procedure.28 Page 10 REPRINTED ARTICLE - ©2008 Pennsylvania Patient Safety Authority Vol. 5, No. 1—March 2008 Pennsylvania Patient Safety Advisory Calculation Awareness In most cases of diagnostic radiology, fetal dose esti- Increasing public awareness of the safety of low-dose mation is unnecessary unless the fetus is in the direct diagnostic radiation may reduce anxiety and prevent beam. If the fetus is in the direct beam or if a woman test delays or termination of otherwise wanted preg- is unaware she is pregnant at the time of a high-dose nancies.10 Heightening physician awareness about x-ray procedure, a qualified expert (i.e., a medical diagnostic radiation doses and effects may promote physicist/radiation safety specialist who is experienced accurate estimation of diagnostic radiation risk and with dosimetry) can calculate the estimated radiation therefore more appropriate patient counseling.1,13 dose to the conceptus/fetus.1,24 The medical professional who prescribes or uses radia- The qualified expert calculates a case-specific, esti- tion needs to be familiar with the effects of radiation mated fetal dose, rather than referring to average on the conceptus. The associated risk is low with less doses published in the clinical literature.15 Then, this than 100 mGy (10 rad) of radiation exposure, except dose is compared to the date of conception or date of during the pre-implantation stage of pregnancy (refer to last menstrual period to determine fetal risks associ- Table 4). The risk of carcinogenesis related to ionizing ated with the length of the gestation.24 radiation throughout pregnancy is unclear, but a study Pregnancy Presumption/Determination by ICRP indicates that it is discernable.21 Risks associ- Until proven otherwise, amenorrhea occurring in ated with greater than 100 mGy (10 rad) include CNS regularly menstruating women should be considered abnormalities, malformations, growth restriction, and due to pregnancy.1,24 All women of childbearing age fetal death.1 should be questioned about the possibility of preg- Patient education brochures can provide information nancy prior to diagnostic radiation exposure.1,7,18 about risks associated with diagnostic ionizing radia- Pregnancy testing may be necessary;18 however, tion and pregnancy; for example, see http://www. because fetal doses are usually well below the 1 mGy familydoctor.org. (0.1 rad) used in diagnostic radiology, pregnancy For a given radiographic examination, the range of tests are not usually performed.1,19 Moreover, in most entrance doses (doses measured at the body surface diagnostic radiology situations, the “10-day rule” in at the site where the x-ray beam enters the body) is women of childbearing age has been proven to be very broad. At times, the lowest and highest doses unnecessary.16 But in high-dose procedures involv- measured at individual radiological installations vary ing the lower abdomen and pelvic area in which the by a factor of 100.7 Therefore, facilities can establish embryo-fetus is in the direct beam, it would be pru- diagnostic reference levels for each of the principal dent to conduct a pregnancy test and/or restrict such studies. These levels can be used to identify x-ray radiography to the first 10 days of the woman’s men- machines in need of corrective actions, thus reducing strual cycle.16 In high-dose procedures, the absorbed the average facility-specific radiation dose to patients.7 fetal dose might range by a factor of 10 to 100.1,7,15,16 Moreover, regular preventive maintenance will help to Thus, the absorbed dose may be above the threshold ensure that the equipment is in proper working order dose for malformations, and cancer risk becomes and is providing an appropriate dose of radiation. appreciable. When a patient is pregnant or possibly pregnant, the Good procedural technique can be promoted through technician or clerk relates the information to the radi- confirming staff competencies and monitoring tech- ologist. The radiologist, in turn, determines whether niques utilized.7 the embryo/fetus will be in the primary x-ray beam. If Notice not, the risk to the fetus is very low, and the best risk Consider posting notices in several places within reduction strategy is good radiologic practice.1 diagnostic radiology departments or wherever diag- While pregnancy testing is not necessary for low-dose, nostic x-ray equipment is used, advising patients who low-risk diagnostic radiation procedures, testing may are pregnant or could be pregnant to inform a staff be prudent prior to high-dose procedures, particularly person prior to the procedure.1 These notices could of the abdomen and pelvis. As communicated in PA- also be posted in reception/waiting areas and written PSRS reports, patients who have firmly denied the in the predominant languages of the communities possibility of pregnancy have undergone high-dose diag- served by the facility. Using pictures instead of text nostic procedures during which fetuses were revealed. in the notices may help to convey to individuals from different languages or cultures the need to report Another issue identified in PA-PSRS reports is the actual/potential pregnancies.17 performance of imaging procedures prior to the return of pregnancy test results. Facilities may address Documentation this issue by evaluating/improving systems and pro- When ordering diagnostic radiation procedures, cesses to improve turnaround time of pregnancy test providing to the radiologist adequate clinical infor- results or implementing point-of-care testing that mation, the suspected diagnosis, and/or reason for involves personnel who have the competencies to the examination will prevent wrong procedures, conduct and interpret these tests prior to conducting techniques, and/or useless tests.7 When a high-dose such diagnostic procedures. diagnostic procedure is performed and the fetus is in Vol. 5, No. 1—March 2008 REPRINTED ARTICLE - ©2008 Pennsylvania Patient Safety Authority Page 11 Pennsylvania Patient Safety Advisory the primary x-ray beam, documenting the following doses greater than 500 mGy (50 rad), there can be technical factors will provide information required for significant fetal damage, of which the magnitude and the medical physicist/qualified expert to calculate an type depend upon the dose and stage of pregnancy.1,24 accurate fetal radiation dose. Three to 16 weeks after conception, if the absorbed fetal dose is in excess of 500 mGy, there is a substan- For all modes of diagnostic radiation, document the tial risk of growth retardation and CNS damage. following as applicable: film projections, geometrical The fetus may survive, but the parents need to be description, dose area product, beam filtration, x-ray informed of the high risks involved.1 generator settings (mAs and kVp); and whether a grid was used.1,18,27 In addition, for x-rays, document A qualified biomedical or health physicist should the number of films and locations.27 For fluoroscopy, calculate the absorbed fetal dose as accurately as pos- additional information includes beam time.27 For CT sible. Then the physician provides information and scans, additional information includes slice thickness, determines the situation/perspective of the parents. number of slices, pitch (distance between adjacent The parents will make decisions after being fully slices), and location of the uterus.27 informed.1 The healthcare professional should document the Information provided may include the following:1,16 details related to counseling and consents in the ■ Analysis of gestational age patient’s medical record.1 ■ Estimation of fetal dose and risks of in utero radia- Counseling/Consent tion exposure A pregnant patient has a right to know the extent and type of potential radiation effects that might ■ Benefit of radiological examination for the mother result from in utero radiation exposure.1 The extent and medical indication of disclosure is determined by what a reasonable per- ■ Maternal risk if the examination were postponed son believes is material to a mother’s decision to be until after delivery exposed to radiation.1 ■ Comparison of radiation risks with other environ- The scope of information provided to a pregnant mental hazards in ordinary life patient is related to the level of risk to the fetus.1 ■ Spontaneous incidence of fetal abnormalities in For low-dose procedures such as a chest x-ray, verbal populations without diagnostic radiation exposure assurances can be provided that the risk is extremely low and this discussion can be documented in the One approach suggested is to indicate to the mother patient’s medical record or radiology report.30 When the probability of not having a child with a malforma- fetal doses are 1 mGy (0.1 rad) or greater, more tion or cancer and how that probability is affected by detailed information is given.1 diagnostic radiation exposure.1,17 Another approach is to present a graph that compares the radiation The clinician ordering the imaging procedure is dose of various diagnostic studies and/or environ- responsible for counseling the pregnant woman and mental sources with the threshold limit of 5 rad. The obtaining informed consent, in consultation with patient’s specific study could be plotted on the graph the radiologist.20 Women who have had routine plain for comparison.6,17 films of the head, chest (including mammograms), and extremities (not the hip), or CT of the head or For higher dose tests (e.g., CT of the abdomen or chest, may be counseled that the following risks to the pelvis, barium enema, IVP, lumbar spine, hip radio- fetus are not increased: miscarriage, growth restric- graph), it may be prudent to obtain written informed tion or congenital malformation (e.g., microcephaly), consent.30 One example of such a form was developed or mental retardation.34 The benefits outweigh most by the University of California, San Francisco.30 If a risks.20 While any one diagnostic radiology procedure patient states she is or may be pregnant and the proce- is below the threshold, the fetuses of women exposed dure involves ionizing radiation, the procedure should to radiation exceeding a cumulative dose of more not be performed unless a radiologist is consulted.30 than 50 mGy (5 rad) may be at risk.6 If the patient has limited English proficiency, obtain- Pregnant women may also be counseled that the risk ing consent before the procedure and counseling a of a fetus developing childhood cancer is less than pregnant woman after a procedure using ionizing 1%.34 Fetal exposures to diagnostic radiation in doses radiation is considered critical communication. A cer- less than 100 mGy (10 rad) are not considered a rea- tified language interpreter is required to ensure that son for termination of pregnancy.1,24 One author has the patient understands the information provided suggested that for direct fetal exposure of greater than prior to making decisions. 1 mGy (0.1 rad) a more detailed explanation can be Communication given indicating minimal risk below 10 mGy (1 rad).20 Even though diagnostic radiation is unlikely to cause In the fetal dose range of 100 mGy to 200 mGy harm to the fetus, it is not appropriate to promise (10 rad to 20 rad), the situation is less clear.1 There parents a perfect baby because there are baseline risks appears to be a risk of measurable IQ loss if the fetus associated with pregnancy even without diagnostic is exposed between 8 to 15 weeks gestation. At fetal radiation.6 Page 12 REPRINTED ARTICLE - ©2008 Pennsylvania Patient Safety Authority Vol. 5, No. 1—March 2008 Pennsylvania Patient Safety Advisory Open communication with the patient about the nature of the test, potential outcomes, and risks Accompanying Resources encourages a trusting relationship both before and after Visit the Pennsylvania Patient Safety Authority a diagnostic study.6 Such communication can alleviate (http://www.psa.state.pa.us) for resources that patient concerns about the effects of radiation.25 include the following: When healthcare workers (physicians, technicians, ■ A pocket resource discussing radiation doses radiologists, nurses) work closely together with the of common diagnostic procedures and patient, they can determine the most appropriate effects according to stage of pregnancy study that will obtain the maximum amount of ■ A patient record to track cumulative radiation information while reducing exposure of the fetus to exposure ionizing radiation.20,25 To view the resources, click on “Advisories and Related Resources” in the left-hand column of the Key Points1,6,7,12,17,24 Authority’s home page. Next, click on “Resources The following key points can help promote the safe Associated with Patient Safety Advisory Articles.” use of diagnostic ionizing radiation in pregnant women: ■ Prenatal doses from most properly performed diag- misunderstanding about the effects of such expo- nostic procedures present no measurable increase sure on the conceptus. of fetal death, malformation, or impairment of mental development over background incidence of ■ When healthcare workers (e.g., physicians, techni- these complications. cians, radiologists, nurses) work closely together with the patient, the study most appropriate for ■ If a diagnostic radiology examination is required the situation can be determined so the pregnant to guide diagnosis and treatment, the risk to the patient obtains the maximum amount of infor- mother of not performing the procedure is usually mation while reducing exposure of the fetus to greater than the risk of potential harm to the fetus. ionizing radiation. ■ Ultrasound and MRI are considered safe alter- Notes natives to ionizing radiation and can be used 1. International Commission on Radiological Protection throughout the pregnancy. (ICRP). Pregnancy and medical radiation. ICRP Publica- ■ There are radiation-associated risks throughout tion No. 84. Kidlington, Oxford (United Kingdom): pregnancy relative to the fetal absorbed radiation Elsevier; 2000. dose and the stage of pregnancy. The most signifi- 2. Ratnapalan S, Bona N, Koren G. Ionizing radiation dur- cant radiation risks occur during organogenesis ing pregnancy. Can Fam Physician 2003 Jul;49:873-4. and the early fetal period. During those periods, 3. Henshaw SK. Unintended pregnancy in the United non-urgent x-rays can be avoided. States. Fam Plann Perspect 1998 Jan-Feb;30(1):24-9, 46. ■ Many complex factors are involved in an individ- 4. World Health Organization. Ionizing radiation [online]. ual’s decision to terminate a pregnancy, including [cited 2007 Jun 28]. Available from Internet: http:// fetal radiation exposure information and religious, www.who.int/ionizing_radiation/about/what_is_ir/en/ ethical, and individual beliefs, as well as laws and index.html. regulations. However, a fetal dose below 10 rad 5. U.S. Environmental Protection Agency. Ionizing & non- (100 mGy) is not considered a reason for terminat- ionizing radiation [online]. 2007 Nov 15 [cited 2008 ing a pregnancy. Jan 21]. Available from Internet: http://www.epa.gov/ ■ The majority of diagnostic procedures, excluding radiation/understand/ionize_nonionize.html. pelvic CT and barium enema, do not involve fetal 6. Toppenberg KS, Hill DA, Miller DP. Safety of radio- exposure of greater than 50 mGy (5 rad) and are graphic imaging during pregnancy. Am Fam Physician not, therefore, usually associated with known deter- [online]. 1999 Apr 1 [cited 2008 Jan 21]. Available from ministic effects (malformation, mental retardation). Internet: http://www.aafp.org/afp/990401ap/1813.html. ■ The main practical issue following in utero exposure 7. International Commission on Radiological Protection. at diagnostic levels is the increased risk of cancer. Radiation and your patient: a guide for medical practi- tioners. Ann IRCP 2001;31(4):5-31. ■ It is important to know the patient’s pregnancy sta- tus with as much certainty as possible. One should 8. Centers for Disease Control and Prevention. Radiation not rely on the patient’s history alone. measurement. [radiation emergencies fact sheet online]. 2006 May 10 [cited 2007 Jul 19]. Available from Inter- ■ Pregnant women should be informed in writing net: http://www.bt.cdc.gov/radiation/measurement.asp. of the radiation dose and date of the procedure so that cumulative effects can be appreciated. 9. Science terms: distinctions, restrictions, and confusions: rad/rem/roentgen/gray/sievert. Bartleby.com [online]. ■ Patient counseling before and/or after diagnostic 1996 [cited 2007 May 17]. Available from Internet: radiation exposure can help reduce anxiety and http://www.bartleby.com/64/C004/037.html. Vol. 5, No. 1—March 2008 REPRINTED ARTICLE - ©2008 Pennsylvania Patient Safety Authority Page 13 Pennsylvania Patient Safety Advisory 10. Cohen-Kerem R, Nulman I, Abramow-Newerly M, and fetus). ICRP Publication No. 90. Kidlington, Oxford et al. Diagnostic radiation in pregnancy: perception ver- (United Kingdom): Elsevier; 2003. sus true risks. J Obstet Gynaecol Can 2006 Jan;28(1):43-8. 22. Greskovich JF Jr, Macklis RM. Radiation therapy in 11. Bentur Y, Horlatsch N, Koren G. Exposure to ionizing pregnancy: risk calculation and risk minimization. Semin radiation during pregnancy: perception of teratogenic Oncol 2000 Dec;27(6):633-45. risk and outcome. Teratology 1991 Feb;43(2):109-12. 23. Centers for Disease Control and Prevention. Prenatal 12. Trichopoulos D, Zavitsanos X, Koutis C, et al. The radiation exposure: a fact sheet for physicians. [emer- victims of Chernobyl in Greece: induced abortions gency preparedness & response fact sheet online]. 2005 after the accident. Br Med J (Clin Res Ed) 1987 Oct Mar 23 [cited 2008 Jan 21]. Available from Internet: 31;295(6606):1100. http://www.bt.cdc.gov/radiation/prenatalphysician.asp. 13. Ratnapalan S, Bona N, Chandra K, et al. Physician’s 24. International Atomic Energy Agency. Radiologic protec- perceptions of teratogenic risk associated with radiogra- tion of patients: pregnancy and radiation in diagnostic phy and CT during early pregnancy. AJR Am J Roentgenol radiology. [online]. [cited 2008 Jan 21]. Available from 2004 May;182(5):1107-9. Internet: http://rpop.iaea.org/RPoP/RPoP/ Content/SpecialGroups/1_PregnantWomen/ 14. ACOG Committee on Obstetric Practice. ACOG PregnancyAndRadiology.htm. Committee Opinion. Number 299, September 2004 25. Smits AK, Paladine HL, Judkins DZ, et al. Clinical (replaces No. 158, September 1995). Guidelines for diag- inquiries. What are the risks to the fetus associated with nostic imaging during pregnancy. Obstet Gynecol 2004 diagnostic radiation exposure during pregnancy? J Fam Sep;104(3):647-51. Pract 2006 May;55(5):441-2,444. 15. De Santis M, Di Gianantonio E, Straface G, et al. Ion- 26. Brent RL. Commentary on JAMA article by Hujoel izing radiation in pregnancy and teratogenesis: a review et al. Health Phys 2005 Apr;88(4):379-81. of literature. Reprod Toxicol 2005 Sep-Oct;20(3):323-9. 27. Karam PA. Determining and reporting fetal radiation 16. Kusama T, Ota K. Radiological protection for diagnostic exposure from diagnostic radiation. Health Phys 2000 examination of pregnant women. Congenit Anom (Kyoto) Nov;79(5 Suppl):S85-90. 2002 Mar;42(1):10-14. 28. American Dental Association. American Dental Associa- 17. Harding LK, Thomson WH. Radiation and pregnancy. tion statement on “antepartum dental radiography and Q J Nucl Med 2000 Dec;44(4):317-24. infant low birth weight” [press release online]. 2004 Apr 28 [cited 2008 Jan 21]. Available from Internet: http:// 18. Timins JK. Radiation during pregnancy. N J Med 2001 www.ada.org/public/media/releases/0404_release03.asp. Jun;98(6):29-33. 29. Lockwood D, Einstein D, Davros W. Diagnostic imag- 19. Sharp C, Shrimpton JA, Bury RF. Diagnostic medical ing: radiation dose and patients’ concerns. Cleve Clin J exposures: advice on exposure to ionizing radiation dur- Med 2006 Jun;73(6):583-6. ing pregnancy [online]. Chilton, Didcot, Oxon (UK): National Radiological Protection Board. 1998 [cited 30. Coakley F, Gould R. Guidelines for the use of CT and 2007 Jul 19]. Available from Internet: http://www. MRI during pregnancy and lactation. Chapter 5. In: e-radiography.net/regsetc/nrpb_asp8/Diagnostic UCSF imaging of retained surgical objects in the abdo- Medical Exposures Advice on Exposure to Ionising men and pelvis section handbook [online]. University Radiation during Pregnancy.htm. of California, San Francisco Department of Radiol- ogy. 2005 [cited 2007 Jun 6]. Available from Internet: 20. Lowe SA. Diagnostic radiography in pregnancy: http://www.radiology.ucsf.edu/instruction/abdominal/ risks and reality. Aust N Z J Obstet Gynaecol 2004 ab_handbook/05-CT_MRI_preg.html. Jun;44(3):191-6. 31. ECRI Institute. Radiation dose in computed tomogra- 21. International Commission on Radiological Protection phy: why it’s a concern and what you can do about it. (ICRP). Biological effects after prenatal irradiation (embryo Health Devices 2007 Feb;36(2):41-2, 44-63. Page 14 REPRINTED ARTICLE - ©2008 Pennsylvania Patient Safety Authority Vol. 5, No. 1—March 2008 ? Pennsylvania Patient Safety Advisory ? Self-Assessment Questions 1. The central nervous system of the fetus is most sensitive to ionizing radiation during which of the following? 4. During a nine-month gestation, the conceptus usually receives how much natural ionizing radiation? a. Pre-implantation a. 1 mGy (0.1 rad) b. Organogenesis b. 10 mGy (1 rad) c. Early fetal development c. 20 mGy (2 rad) d. a and b only d. 30 mGy (3 rad) e. b and c only 5. Sources of natural background ionizing radiation include which of the following 2. Medically necessary x-rays of the head, chest, and arms can a. Heat and light be performed on a pregnant woman at any time during the pregnancy. b. Sound waves and microwaves c. Sun and rocks a. True d. All of the above b. False 6. Absorbed fetal radiation can be calculated accurately 3. Fetal radiation doses for a fluoroscopic procedure are as by referring to average doses published in the clinical easy to calculate as for a radiograph. literature. a. True a. True b. False b. False Vol. 5, No. 1—March 2008 REPRINTED ARTICLE - ©2008 Pennsylvania Patient Safety Authority Page 15 PENNSYLVANIA PATIENT SAFETY ADVISORY This article is reprinted from the Pennsylvania Patient Safety Advisory, Vol. 5, No. 1—March 2008. The Advisory is a publication of the Pennsylvania Patient Safety Authority, produced by ECRI Institute and ISMP under contract to the Authority as part of the Pennsylvania Patient Safety Reporting System (PA-PSRS). Copyright 2008 by the Pennsylvania Patient Safety Authority. This publication may be reprinted and distributed without restriction, provided it is printed or distributed in its entirety and without alteration. Individual articles may be reprinted in their entirety and without alteration provided the source is clearly attributed. This publication is disseminated via e-mail. To subscribe, go to https://www.papsrs.state.pa.us/ Workflow/MailingListAddition.aspx. To see other articles or issues of the Advisory, visit our Web site at http://www.psa.state.pa.us. Click on “Advisories” in the left-hand menu bar. THE PENNSYLVANIA PATIENT SAFETY AUTHORITY AND ITS CONTRACTORS The Patient Safety Authority is an independent state agency created by Act 13 of 2002, the Medical Care Availability and Reduction of Error (“Mcare”) Act. Consistent with Act 13, ECRI Institute, as contractor for the PA-PSRS program, is issuing this publication to advise medical facilities of immediate changes that can be instituted to reduce Serious Events and Incidents. For more information about the PA-PSRS program or the Patient Safety Authority, see the Authority’s Web site at www.psa.state.pa.us. ECRI Institute, a nonprofit organization, dedicates itself to bringing the discipline of applied scientific research in healthcare to uncover the best approaches to improving patient care. As pioneers in this science for nearly 40 years, ECRI Institute marries experience and independence with the objectivity of evidence-based research. More than 5,000 healthcare organizations worldwide rely on ECRI Institute’s expertise in patient safety improvement, risk and quality management, and healthcare processes, devices, procedures and drug technology. The Institute for Safe Medication Practices (ISMP) is an independent, nonprofit organization dedicated solely to medication error prevention and safe medication use. ISMP provides recommendations for the safe use of medications to the healthcare community including healthcare professionals, government agencies, accrediting organizations, and consumers. ISMP’s efforts are built on a non-punitive approach and systems-based solutions.