Objective: To evaluate the correlation between preterm delivery before 37 weeks of gestation and ultrasound elastography strain measurement of cervical stiffness.
Study design: In this prospective study, 182 pregnant women were examined vaginally by ultrasound elastography from a mid-sagittal plane. Cervical length was measured and strain was calculated in four regions of interest on the anterior cervical lip. First, the software was validated by intraobserver variability. Second, strain and strain ratios were calculated with adjusted software presets and correlated to the outcome of spontaneous preterm delivery (sPTD).
Result: A total of 8928 regions of interest (ROIs) and 6696 ratios were evaluated. The median gestational age at examination was 26 ± 6.1 weeks. A median maternal age of 33 ± 5.6 and a medial parity of 1 ± 0.9 were observed. Intra-Class-Correlation values in validation phase ranged from 0.893 to 0.967. The prevalence of sPTD was 11.9%. Strain ratio Rselective was identified as the best predictor of preterm delivery. Rselective values >0.89 were associated with preterm delivery with a sensitivity of 0.59 and a specificity of 0.86 (odds ratio=1.474 for an increase of 0.1 in Rselective; P=0.002).
Conclusion: Ultrasound elastography strain measurement of cervical stiffness is correlated with the predictability of preterm delivery.