Is Magnetic Resonance Imaging (MRI) safe during pregnancy?

From the Guidelines

MRI is generally considered safe during pregnancy when medically necessary, but it is recommended to avoid gadolinium-based contrast agents due to their potential to cross the placenta and accumulate in the fetal urinary tract. While there are no known harmful effects to the fetus from MRI, doctors typically recommend avoiding MRI during the first trimester unless absolutely necessary, as a precautionary measure 1. MRI does not use ionizing radiation like X-rays or CT scans, which makes it safer than those imaging techniques during pregnancy. Instead, MRI uses magnetic fields and radio waves to create detailed images.

Key Considerations

• If contrast agents are needed, gadolinium-based agents are usually avoided during pregnancy as they can cross the placenta 1.
• Before having an MRI while pregnant, inform your healthcare provider about your pregnancy so they can determine if the benefits outweigh any potential risks 1.
• They may also consider alternative imaging methods or postponing the scan if possible.
• Some facilities may require a written consent form or a note from your obstetrician before performing an MRI on a pregnant woman 1.
• During the procedure, you'll be positioned carefully to ensure comfort and safety for both you and your baby.

Safety and Precautions

• The use of contrast in MRI during pregnancy should be done with caution, because the gadolinium-chelate molecules are excreted in the amniotic fluid and may remain there for an indeterminate amount of time before finally being reabsorbed and eliminated 1.
• Gadolinium is considered a pregnancy category C drug (it should be administered only if the potential benefit outweighs the risk) because animal studies have revealed adverse effects 1.
• If the information requested from the MRI study with intravenous (IV) contrast cannot be acquired using other modalities and is needed to potentially affect the care of the patient or fetus during the pregnancy, and the ordering physician believes that it is not prudent to wait until the patient is no longer pregnant, IV contrast may be administered and the rationale diligently documented 1.

From the Research

MRI Safety During Pregnancy

• MRI is commonly used in pregnant women to evaluate various pathologies, including acute abdominal and pelvic pain, placental abnormalities, and fetal abnormalities 2.
• The use of MRI during pregnancy offers excellent spatial and contrast resolution without exposing patients to ionizing radiation 2, 3.
• However, there are concerns about the safety of gadolinium-based contrast agents, which can cross the placental barrier and potentially harm the fetus 2, 3, 4.

Use of Contrast Agents

• The administration of gadolinium-based contrast agents during pregnancy is a topic of debate, with some studies suggesting a potential risk of adverse outcomes in infants exposed to these agents 4, 5.
• Other studies have found no definitive evidence of harm, but highlight the need for further research to fully understand the safety of these agents during pregnancy 4, 6.
• Some experts recommend avoiding the use of gadolinium-based contrast agents during pregnancy whenever possible, and considering alternative imaging modalities such as non-contrast MRI or ultrasound 3, 4.

Current Recommendations

• The current evidence suggests that MRI is safe to use during pregnancy, but prospective and longitudinal studies are lacking to fully understand its safety profile 5.
• Healthcare providers should carefully weigh the benefits and risks of using MRI and gadolinium-based contrast agents during pregnancy, and consider alternative imaging modalities when necessary 3, 4, 6.