Abstract:

Objective To evaluate the association between cervical insufficiency （CI） and spontaneous preterm birth （SPB）， and to investigate the predictive value of shear wave elastography （SWE）， cervical length （CL）， and anterior cervical angle （ACA） in identifying SPB resulting from CI. Methods This study recruited 786 pregnant women who attended prenatal outpatient clinics or were hospitalized for treatment at the Affiliated Hospital of Nantong University and the Maternity Hospital affiliated with Jiangnan University from June 2023 to January 2024. Among these participants， 723 were full-term pregnancies and 63 were preterm pregnancies. Cervical SWEI， CL， and cervical ACA were measured using a Mindray Resona R9 Pro/Eagus R9s ultrasound device equipped with shear wave elasticity imaging software. Additionally， the participants were categorized into four gestational age groups： 19-23⁺⁶ weeks， 24-27⁺⁶ weeks， 28-33⁺⁶ weeks， and 34-36⁺⁶ weeks， to evaluate the relationship between gestational age and ultrasound parameters. Results The mean CL in the preterm group was 25.4 mm， significantly shorter than the 29.7 mm observed in the full-term group （P < 0.001）. The ACA in the preterm group was 121°， which was significantly higher than the 99° in the full-term group （P < 0.001）. Additionally， SWE values were significantly lower in the preterm group compared to the full-term group at all measured cervical sites： anterior external os （AE） 6.47 kPa versus 9.91 kPa （P < 0.001）， anterior internal os （AI） 10.98 kPa versus 18.62 kPa （P < 0.001）， posterior internal os （PI） 11.32 kPa versus 21.09 kPa （P < 0.001）， and posterior external os （PE） 8.16 kPa versus 13.24 kPa （P < 0.001）. A significant negative correlation was found between CL and gestational age （r = -0.278， P = 0.001）. The combined predictive indicators demonstrated high accuracy and specificity for predicting preterm birth， with an area under the curve （AUC） of 0.952， sensitivity of 95%， and specificity of 86%. Conclusions The integration of cervical SWE， CL measurement， and assessment of the angle of ACA can substantially enhance the predictive accuracy for SPB due to CI. This multimodal approach offers clinicians a more robust and precise tool for identifying high-risk pregnancies， enabling timely interventions that can reduce the incidence of preterm birth and improve maternal and neonatal outcomes.

Key words: cervical insufficiency, spontaneous preterm birth, shear wave elasticity imaging, cervical length, anterior cervical angle