MRI of the Cervix More Accurate Than Ultrasound at Predicting Preterm Birth

Women with a cervix measuring 15 mm or less, as measured using an ultrasound exam in the second trimester of pregnancy, are considered to have an increased risk of preterm birth.

The researchers used Diffusion-Weighted Imaging Magnetic Resonance Imaging (DWI-MRI) to examine pregnant women with suspected fetal or placental abnormality. The thirty pregnant women that took part in the study all had a short cervix, and underwent a positive fetal fibronectin test between the 23rd and 28th weeks of gestation. Eight of the women delivered within one week of the MRI examination, and the other 22 delivered 55 days later on average.

The researchers compared ADC values, using MRI data, between the inner, sub-glandular zone and the outer, stromal area of the cervix and found that the sub-glandular ADC was higher in patients with impending delivery. This suggested increased mobility of water molecules in that area, consistent with cervical ripening.

Lead author of the study, Gabriele Masselli, MD, Radiology Department, Sapienza University (Rome, Italy), said, “Our results indicate that a high ADC value recorded at the level of the subglandular area of the cervix is associated with the imminent delivery of asymptomatic patients with a short cervix. In detail, the subglandular ADC was inversely correlated to the time interval between MRI and delivery and therefore emerged as a powerful imaging biomarker in evaluating patients with impending delivery.”

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Sapienza University