Gadolinium exposure during pregnancy

While gadolinium-based contrast agents (GBCAs) are used in approximately 30% to 45% of magnetic resonance imaging (MRI) examinations in the United States, the frequency of their use in pregnant patients is not clear. A recent study in Radiology aimed to examine characteristics of real-world use patterns among a large sample of American women.

The study used data from the Sentinel Initative, which reflect experience from approximately 310 million patients from 2010 to 2018. Approximately 52% of the subjects were female and 29% were aged 15 to 44. The authors retrospectively identified live-birth pregnancies occurring between 2006 and 2017 using an algorithm based on International Classification of Diseases, 9^th and 10^th Revision codes. They defined first-trimester exposure as one that occurred between days 14 and 90 of gestation, second-trimester exposure as one that occurred between days 90 to 180 and a third-trimester exposure as one that occurred between day 181 through the day prior to delivery.

Outpatient MRIs performed with or without GBCA between January 2006 and December 2017 were identified by the authors. The primary analysis evaluated exposure from conception (last menstrual period + 14 days) through the day prior to hospital admission for delivery. Each pregnancy was matched 1:1 by age, calendar years and contributing data to a woman who did not deliver a live-born neonate during this period.

The pregnancy cohort included a total of 6,879 GBCAs administered in 5,457 pregnancies (1 GBCA exposure per 860 pregnancies [0.12%]). The most frequent location for gadolinium-enhanced MRI among pregnant women was the head (0.7 per 1000 pregnancies) with 2,968 of 3,499 (84.8%) head MRI procedures performed to image the brain. Headache, including migraine, was the most common location grouping of diagnostic codes billed for each semester. Abdominal and pelvic imaging locations represented 22.3% (1536 of 6879) of contrast-enhanced and 39.1% (28,514 of 72,687) of unenhanced MRI procedures during pregnancy.

The majority (70.2%) of GBCA exposure occurred during the first trimester and prevalence of exposure was 4.3-fold greater during the first trimester (n=4008) than during the second trimester (n=925) and 5.1-fold greater than during the third trimester (n=779).

The authors believe that their findings indicate that higher rates of gadolinium exposure occur earlier in pregnancy and that much of the exposure may be inadvertent before a patient realizes she is pregnant. They note that the American College of Radiology recommends screening women of reproductive age for pregnancy before any MRI evaluation and also that GBCAs should only be used after careful consideration. Ob/gyns who are considering referring a patient to MRI should screen appropriately before doing so.