Value of shear wave elastography combined with cervical length in predicting spontaneous preterm birth at 20 to 27 weeks of gestation

Objective To explore the value of shear wave elastography (SWE) combined with cervical length (CL) measurement in predicting spontaneous preterm birth (SPB) at 20 to 27 weeks of gestation.

Methods A total of 161 pregnant women with antenatal care and examination in the hospital from January 2020 to June 2022 were selected as research objects. All pregnant women underwent CL measurement and SWE detection by ultrasound during 20 to 27 weeks of gestation to obtain CL and SWE parameters. The occurrence of SPB was followed up, and the correlations of CL and SWE parameters with the occurrence of SPB were analyzed.

Results Among the 161 pregnant women, 34 patients experienced SPB. There were significant differences in the external os strain (EOS), elastic contrast index (ECI), internal os strain (IOS), and hardness ratio (HR) of SWE parameters between pregnant women with and without preterm birth (P < 0.05). Similarly, there was a significant difference in CL between the two groups (P < 0.05). Spearman correlation analysis showed that ECI, IOS and EOS were positively correlated with the occurrence of preterm birth (P < 0.05), while HR and CL were negatively correlated with the occurrence of preterm birth (P < 0.05). The receiver operating characteristic (ROC) curve showed that the area under the curve (AUC) for CL in predicting preterm birth was 0.800, with a cut-off value of 2.710 cm. Among the SWE parameters, the AUCs for ECI, HR, IOS and EOS in predicting preterm birth were 0.651, 0.642, 0.705 and 0.653 respectively, with cut-off values of 5.140, 53.650%, 0.320 and 0.330 respectively. The ROC curve showed that the AUC for predicting preterm birth by SWE parameters combined with CL was 0.813, which was significantly higher than the AUC for prediction by the combination of the four SWE parameters (P < 0.05). The sensitivity and specificity at the maximum Youden index were 0.794 and 0.732 respectively.

Conclusion CL, as well as ECI, HR, IOS and EOS among SWE parameters, have certain value in predicting SPB in pregnant women at 20 to 27 weeks of gestation, especially when the five indicators are combined for prediction. The critical values for prediction are 2.710 cm, 5.140, 53.650%, 0.320 and 0.330 respectively.