January 12, 2009
Radiation Exposure and Pregnancy — Considerations for Women Who Are or May Be Pregnant
By Leonard Berlin, MD, FACR
Vol. 10 No. 1 P. 24
Editor’s Note: Leonard Berlin, MD, FACR, is a professor of radiology at Rush University Medical College and the chairman of the department of radiology at Rush North Shore Medical Center in Skokie, Ill. He began writing on risk management and malpractice issues in a series of articles in the American Journal of Roentgenology. Those articles became the basis for his well-known book Malpractice Issues in Radiology. This Risk Management & Malpractice Defense column is drawn from that book.
The third edition of Malpractice Issues in Radiology is scheduled for release early this year and will be available from the American Roentgen Ray Society.
Case 1. A 30-year-old woman with symptoms of hyperthyroidism was referred to a hospital’s nuclear medicine department for a radionuclide uptake and scintigram of the thyroid gland, for which she was given 696 µCi (25.75 MBq) of iodine-131. The radiologist interpreted the test findings as normal. Soon thereafter the patient learned that she was pregnant. It was determined that the fetus had been at 5 weeks’ gestation and had received an estimated radiation dose of 340 mrad (0.0034 Gy) during administration of the radioactive iodine. During week 28 of gestation, the patient went spontaneously into labor and delivered a premature baby with multiple congenital anomalies. The infant died 2 months later.
Case 2. A 28-year-old woman with complaints of abdominal pain and a history of spastic colon consulted her family physician. Because the patient thought that she might be pregnant, the physician ordered a pregnancy test and results were reported as negative. He then referred the woman to a hospital’s radiology department for a lower gastrointestinal series and a chest radiograph that the radiologist interpreted as showing normal findings. Two weeks later the patient underwent another pregnancy test, with positive results. Subsequent sonographic examination revealed that the fetus had been at 4 weeks’ gestation when the woman underwent the lower gastrointestinal and chest radiology studies. The patient asked her family physician whether a therapeutic abortion would be necessary, but the physician and the radiologist advised her that the radiation exposure, estimated to be approximately 1 rad (0.01 Gy), was insufficient to injure the fetus. At the end of a full-term pregnancy, the patient delivered a male neonate who had several birth defects, including microcephaly and congenital heart disease.
Case 1. The patient filed a malpractice suit against the radiologist, claiming that he was negligent in failing to perform a pregnancy test before the administration of radioactive iodine and for failing to recommend therapeutic abortion once it was known that the patient was pregnant during the radiation exposure. In a pretrial deposition, a radiology expert for the plaintiff testified that the defendant radiologist had a duty to obtain a menstrual history from the patient before radiologic testing and that no amount of radiation is without adverse effect on a fetus. The radiology expert said that the radioactive iodine could have caused the fetal anomalies, but he could offer no supporting scientific data. A radiology expert for the defense refuted these contentions, stating that a menstrual history was not required and that no scientific evidence indicated that a radiation dose of less than 1 rad would cause fetal anomalies. The defense rejected offers to settle the case and was prepared to go to trial, but the plaintiff withdrew the lawsuit before selection of the jury.
Case 2. On behalf of their baby, the parents sued the radiologist, the family physician, and the hospital, alleging negligence in the performance of the original pregnancy test and in advising the patient not to undergo a therapeutic abortion. A radiology expert for the plaintiff testified in a pretrial deposition that the radiation dose the mother received from the lower gastrointestinal and chest radiographic examinations might have caused her baby’s microcephaly and cardiac defects.
A defense expert countered that no causal relationship existed between the radiation exposure and the anomalies. Just before trial, all parties agreed to a settlement of $500,000.
The disparity of outcomes of these two cases with similar claims that fetal anomalies were caused by radiation exposure of 1 rad (0.01 Gy) or less perhaps reflects an unenlightened perception among much of the medical and legal communities that Taylor1 characterized as a “cloud of ignorance or misunderstanding of the fundamental facts about ionizing radiation and its potential hazards.” Taylor pointed out that no one has established a causal relationship between a radiation dose of up to 10 rad (0.1 Gy) and a specific deleterious effect in humans. Taylor also observed that there is a “common feeling among the uninformed public and news media” that in utero radiation is so mysterious that “even the scientists don’t know what is happening there.”
In fact, much is known about the risks of radiation exposure to the fetus. Radiation-induced abnormalities in fetuses who are less than 2 weeks’ gestation or more than 15 weeks’ gestation are extremely unlikely.2 Fetuses between 2 and 15 weeks’ gestation are considerably more sensitive to adverse radiation effects, the most common of which are microcephaly (sometimes combined with mental retardation), other central nervous system defects, and growth retardation.3,4 The radiation dose below which no deleterious effects on the fetus occur even in the most sensitive developmental phase is not known, but it has been estimated to range from 5 to 15 rad (0.05 to 0.15 Gy).5-7 Causal relationships between congenital anomalies and in utero radiation are difficult to evaluate because 5% to 10% of all children born have detectable congenital defects without any history of exposure to radiation.7
Relative agreement exists among most radiation physicists about when, if ever, to recommend therapeutic abortion when radiation exposure has occurred in early pregnancy. The American College of Radiology states, “The interruption of pregnancy is rarely justified because of radiation risk to the embryo or fetus from a radiologic examination.”8 Wagner et al.2 reported that therapeutic abortion is not indicated if exposure to radiation in the diagnostic range occurs before 2 weeks’ or after 15 weeks’ gestation or in the period between those dates if the dose is 5 rad or fewer. Wagner et al. concluded that even in doses up to 15 rad, termination of a pregnancy is probably not indicated solely on the dangers of radiation. Hall7 suggests that 10 rad (0.1 Gy) is a cutoff point above which therapeutic abortion should be considered when the fetus receives such a dose at a gestational age of 10 days to 26 weeks. According to Hall, during this period the fetus is most sensitive to induction of congenital malformations.
Even if radiation exposure exceeds the figures of Wagner et al.2 and Hall7, a recommendation to terminate pregnancy should be based on additional factors, including the hazard of pregnancy to the expectant mother, the ethnic and religious background of the family and their attitudes toward possibly bearing a child with a congenital deformity, state law regarding abortion, genetic factors, age of the mother, and any associated clinical diseases or conditions.
Radiologists frequently become involved with the issue of radiation exposure when a woman who knows she is pregnant prospectively raises a question of whether she should undergo a radiologic examination or when it is discovered that a patient has undergone a radiologic examination not knowing she was pregnant. The first two questions that must be addressed by the radiologist before rendering an opinion on potential dangers are the gestational age of the fetus at the time of exposure and the radiation dose received. Fetal age can be determined by the patient’s physician, but estimating radiation dosage is the responsibility of the radiologist or medical physicist. Radiologists can easily obtain this information from one of the many sources that list radiation doses received during radiologic and radionuclide examinations. Several sources are referenced at the end of this article.6,7,9,10
No governmental regulation or formal professional standard requires that radiologists determine in advance of a radiologic procedure whether a patient of child-bearing age is pregnant. A Health and Human Services publication from 1986, however, made these recommendations: a woman who is or thinks she is pregnant should be encouraged to give this information to the physician; radiology requisition forms that are ordinarily filled out by referring physicians should include a section dealing with the possibility of pregnancy; and radiology technologists should be encouraged to ask each patient whether she is pregnant.9 Although the American College of Radiology has not issued any specific standards on radiation exposure, it did publish a guide on radiation that stated, “Radiologists should be advised of known or possible pregnancy.”10 Saenger and Kereiakes5 suggested placing signs in radiology and nuclear medicine departments that ask each patient to notify a technologist or physician if she is, or thinks she could be, pregnant.
Summary and Risk Management
Malpractice lawsuits alleging that an abortion or fetal anomaly was caused by exposure to diagnostic radiation were relatively common in the 1980s but became less common in the 1990s.11 Nonetheless, radiation exposure to pregnant or possibly pregnant women represents a continuing clinical hazard to the fetus and a medicolegal hazard to the radiologist. Risk management in the radiology practice can lessen the likelihood of incurring a medical malpractice lawsuit and maximize chances for a successful defense if a suit is filed while enhancing good patient care. The following risk management pointers will help radiologists meet all three of these objectives.
• All radiology facilities should have a process to assist in identifying whether women of child-bearing age are pregnant. Commonly used methods include having all radiology requisition forms contain an inquiry about possible pregnancy; posting signs throughout the waiting and examining areas of the radiology department that state, “If you are pregnant or think you are pregnant, please notify a technologist or physician”; authorizing radiology technologists to ask whether patients are or could be pregnant; and offering pregnancy tests to patients who desire them. Again, no governmental regulation, court ruling, or professional standard requires that radiologists determine definitively whether patients are pregnant before radiologic examinations.
• All radiology facilities should have a process for the management of patients who are pregnant or indicate that they may be pregnant. Radiologists or radiation physicists should be available to discuss with such patients the risks of radiation exposure, the risks of postponing or cancelling the radiologic examination, alternative diagnostic methods, and ways of modifying the radiologic examination to reduce radiation (e.g., decreasing the number of radiographic views, shortening fluoroscopy time, and using smaller doses of radionuclide combined with extending scintigraphic count time).
• Radiologists should be knowledgeable about radiation effects and should be accessible to patients, their families, and referring physicians for discussion of these issues.
• All radiology facilities should possess references that list radiation doses given during radiographic, fluoroscopic, and radionuclide imaging.
• All radiologic equipment should be well maintained and periodically inspected for radiation safety. Radiation output should be monitored according to local governmental and hospital policies.
• All discussions with patients about radiation risks should be documented in the radiologic reports.
— This article appeared in its original form in the American Journal of Roentgenology. It is reprinted here with permission of the American Roentgen Ray Society.
Editor’s Note: Since this article was first published, the publication in reference 10 has been revised.12
1. Taylor L. Lauriston Taylor reviews radiation risks. J Nucl Med. 1985;26(2):118-121.
2. Wagner LK, Lester RG, Saldana LR. Exposure of the Pregnant Patient to Diagnostic Radiations: A Guide to Medical Management. Philadelphia: Lippincott; 1985:19-223.
3. Swartz HM, Reichling BA. Hazards of radiation exposure for pregnant women. JAMA. 1978;239(18):1907-1908.
4. Bushong SC. Management of the pregnant employee and pregnant patient. Contemp Diagn Radiol. 1982;5:1-6.
5. Saenger EI, Kereiakes JG. Medical radiation exposure during pregnancy. JAMA. 1979;242:1669.
6. Whalen JP, Balter S. Radiation Risks in Medical Imaging. Chicago: Year Book Medical; 1984: 43-48, 78-79, 83.
7. Hall EJ. Radiobiology for the Radiologist, 4th edition. Philadelphia: J. B. Lippincott Company; 1994: 363-378, 419-452.
8. American College of Radiology. ACR standard for abdominal radiologic examinations of women of child-bearing age and potential. In: Standards. Reston, Va: American College of Radiology; 1988.
9. Embryo, fetus, infant ... Recommendations to minimize diagnostic nuclear medicine exposure. Rockville, Md.: Department of Health and Human Services; 1986. Publication no. HHS/FDA-86-8254
10. American College of Radiology. Medical Radiation: A Guide to Good Practice. Reston, Va.: American College of Radiology; 1985: 4-8.
11. Berlin L, Berlin JW. Malpractice and radiologists in Cook County, IL: Trends in 20 years of litigation. Am J Roentgenol. 1995;165(4):781-788.
12. American College of Radiology. Radiation Risk: A Primer. Reston, Va.: American College of Radiology; 1996: 5-13.