Due to the concern with regard to pregnant technologists and other healthcare workers in the MRI environment, a survey of reproductive health among female MR system operators was conducted by Kanal et al.
Questionnaires were sent to female MR technologists and nurses at the majority of the MRI facilities in the United States. The questionnaire addressed menstrual and reproductive experiences as well as work activities. This study attempted to account for known potential confounding variables (e.g., age, smoking, alcohol use) for this type of data.
Of the 1,915 completed questionnaires analyzed, there were 1,421 pregnancies: 280 occurred while working as an MR employee (technologist or nurse), 894 while employed at another job, 54 as a student, and 193 as a homemaker. Five categories were analyzed that included spontaneous abortion rate, pre-term delivery (less than 39 weeks), low birth weight (less than 5.5 pounds), infertility (taking more than eleven months to conceive), and gender of the offspring.
The data indicated that there were no statistically significant alterations in the five areas studied for MRI healthcare professionals relative to the same group studied when they were employed elsewhere, prior to becoming MRI healthcare employees. Additionally, adjustment for maternal age, smoking, and alcohol use failed to markedly change any of the associations. Menstrual regularity, menstrual cycle, and related topics were also examined in this study. These included inquiries regarding the number of days of menstrual bleeding, the heaviness of the bleeding, and the time between menstrual cycles.
Admittedly, this is a difficult area to objectively examine because it depends on both subjective memory and the memory of the respondent for a given topic. Subjective memory is often inadequate. Nevertheless, the data suggested that there were no clear correlations between MRI workers and specific modifications of the menstrual cycle.
The data from this extensive epidemiological investigation were reassuring insofar as that there did not appear to be deleterious effects from exposure to the static magnetic field of the MR system. Therefore, a policy is recommended that permits pregnant technologists and healthcare workers to perform MRI procedures, as well as to enter the MR system room, and attend to the patient during pregnancy, regardless of the trimester. Importantly, technologists and healthcare workers should not remain within the MR system room or magnet bore during the actual operation of the scanner.
This later recommendation is especially important for those healthcare workers involved in patient management or interventional MR-guided examinations and procedures, since it may be necessary for them to be directly exposed to the MR system's electromagnetic fields at levels similar to those used for patients. These recommendations are not based on indications of adverse effects, but rather, from a conservative point of view and the feeling that there are insufficient data pertaining to the effects of the other electromagnetic fields of the MR system to support or allow unnecessary exposures.
REFERENCES
Evans JA, Savitz DA, Kanal E, Gillen J. Infertility and pregnancy outcome among magnetic resonance imaging workers. J Occu Med 1993;12:1191-1195.
International Commission on Non-Ionizing Radiation Protection (ICNIRP) Statement, Medical magnetic resonance procedures: protection of patients. Health Physics 2004;87:197-216.
Kanal E, Gillen J, Evans J, Savitz D, Shellock FG. Survey of reproductive health among female MR workers. Radiology 1993;187:395-399.
Shellock FG. Magnetic Resonance Procedures: Health Effects and Safety. CRC Press, LLC, Boca Raton, FL, 2001.
Shellock FG, Kanal E. Policies, guidelines, and recommendations for MR imaging safety and patient management. J Magn Reson Imaging 1991;1: 97-101.
Shellock FG, Kanal E. Magnetic Resonance: Bioeffects, Safety, and Patient Management. Second Edition, Lippincott-Raven Press, New York, 1996. |