MRI, or magnetic resonance imaging, uses powerful electromagnetic fields that make tissues hot.
In a study of 1500 children who had been exposed to MRI (without injection of a contrast agent) in the first trimester of pregnancy, vascular, digestive, musculoskeletal and auditory abnormalities and blindness appeared to be more frequent than in those not exposed to MRI.
Gadolinium-enhanced substances are sometimes used intravenously to facilitate the visualisation of the tissue being explored. These contrast agents, particularly those with a linear structure, which are less stable than those with a macrocyclic structure, release gadolinium into the blood, which accumulates in some organs and crosses the placenta.
In 2018, evidence of the effects of exposure to gadolinium during pregnancy were mainly based on a Canadian study. Nearly 400 children exposed to gadolinium through MRI scans during pregnancy were compared to unexposed children (more than one million). According to this study, the risk of death in utero or within 28 days of birth was about four times higher. There may also be an increased risk of damage to certain fibrosis-type tissues.
Based on the data available, before deciding on an MRI scan in pregnancy, with or without gadolinium, it is important to consider how the MRI results might change the clinical course and whether that justifies the risk to the unborn child.
When it is decided to proceed with a gadolinium-enhanced MRI, it is advisable to use a substance with a macrocyclic structure.
©Prescrire 1 February 2019
"Gadolinium, MRI and pregnancy: risks for the child" Prescrire Int 2019; 28 (201): 44-46. (Pdf, subscribers only).
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