MRI in pregnant patients is appropriate when the benefits outweigh the risks
Risks of MRI for the pregnant patient
- Patients in the first trimester of pregnancy might be more susceptible to potential adverse effects including1,2:
- Possible bioeffects of the static magnetic field
- Risks associated with exposure to gradient magnetic fields
- Potential adverse effects of radiofrequency (RF) energy
- Possible adverse effects related to the combination of all three magnetic fields
- In order to properly assess risk with regard to pregnancy, it is recommended that every female patient of childbearing age (between 11-55 years) is asked before a procedure if there is a possibility that she is pregnant3,4 (also see related guideline Pregnant patients).
Appropriate use of MRI in pregnant women
- MRI may be used in pregnant women if other non-ionizing forms of diagnostic imaging are inadequate or if the examination provides important information that would otherwise require exposure to ionizing radiation1,5.
- Before proceeding with MRI, the healthcare team considers the following questions1:
- Would sonography be satisfactory for diagnosis?
- Is the MR procedure appropriate to address the clinical question?
- Is early delivery a consideration?
- Is termination of the pregnancy a possibility?
- MRI should not be withheld when the benefits of the examination clearly outweigh the risks, such as in the following cases1:
- Brain and spine symptoms requiring imaging
- Cancer requiring imaging
- Chest, abdominal and pelvic signs and symptoms of active disease where sonography results are inconclusive
- Specific, suspected cases of fetal anomaly or complex fetal disorder
Obtaining informed consent
- Informed consent is obtained by the radiologist, prior to initiating the exam.
- A consent form is signed by both the patient and the radiologist
MRI with contrast
- Gadolinium enhancement is best avoided when examining the pregnant patient2.
- Research on the risks posed by gadolinum-based contrast for pregnant mothers is limited, and there is insufficient evidence to conclude that it poses no risk to the fetus1
- If it is absolutely necessary to proceed using a contrast agent, a consent form is signed by the patient following an informed consent process which includes an explanation of the potential risks and benefits by the radiologist.
- Pregnant patients are informed that current data shows MRI to be relatively safe for pregnant women with no evidence of deleterious effects in the literature1.
- If the patient is to undergo a procedure requiring gadolinium-based contrast, an explanation is provided regarding the risks of contrast media and the precautions that are being undertaken to avoid unnecessary exposure to risk.
Shellock FG. Reference Manual for Magnetic Resonance Safety, Implants, and Devices. 2012 ed. Los Angeles, CA: Biomedical Research Publishing Group; 2012.
Westbrook C, Kaut Roth C, Talbot J. MRI in Practice. 3rd ed. London, UK: Blackwell Publishing Ltd; 2005.
Martensen, Kathy. Radiographic Image Analysis. St Louis, MO: Saunders Elesvier, 2011.
Health Canada. Safety Code 35: Safety Procedures for the Installation, Use and Control of X-ray Equipment in Large Medical Radiological Facilities. Available from: http://www.hc-sc.gc.ca/ewh-semt/pubs/radiation/safety-code_35-securite/index-eng.php. [Accessed 12 Dec 2019]
Kanal E, et al. American College of Radiology White Paper on MRI safety. AJR 2007;188:1-27.