Magnetic resonance imaging of the cervix in women at high risk for preterm delivery.

OBJECTIVES

To assess whether changes in signal intensity of cervical stroma layers on magnetic resonance imaging (MRI) are associated with spontaneous preterm delivery.

METHODS

Prospective cohort study of women admitted for threatened late miscarriage or preterm delivery between 18 and 34 weeks of gestation. We performed T2-weighted low-field MRI of the uterine cervix among 100 women. Cervical stromal differentiation, defined as the contrast between signal intensities of the inner and outer cervical layers, was classified as high, intermediate, or low by a radiologist blinded to the participant's clinical report. The main outcome measure was the proportion of spontaneous preterm delivery.

RESULTS

Thirty-six women had a spontaneous preterm delivery. The proportion of spontaneous preterm delivery for high, intermediate, and low stromal differentiation was 7/24 (29%), 21/64 (33%; risk ratio 1.1; 95% confidence interval [CI]: 0.6-2.3), and 8/12 (67%; risk ratio 2.3; 95% CI: 1.1-4.8), respectively. The risk of delivering within 7 days increased when stromal differentiation decreased, although the difference was not statistically significant.

CONCLUSIONS

The risk of spontaneous preterm delivery is increased in women with low cervical stromal differentiation on MRI. This risk is also associated with short cervical length, a measurement easier and less costly to obtain by transvaginal ultrasound.