Use of ultrasound shear-wave elastography to evaluate change in cervical stiffness during pregnancy

Abstract

Aim: The aim of this study was to evaluate the usefulness of shear-wave elastography (SWE) for measuring change in cervical stiffness during pregnancy, with regions of interest (ROI) designed for easy identification.

Methods: A total of 280 women were enrolled in this study. SWE was performed at a routine prenatal visit. A measurement area was chosen at the anterior part of the cervix, and a circular ROI 5 mm in diameter was set at two points, 5-10 mm (lower point) and 15-20 mm (upper point) from the external cervical os. The generalized estimating equation was used to estimate the correlation between stiffness and gestational age, using generalized linear models.

Results: There were significant negative correlations between stiffness and gestational age. The estimated regression equations of the lower and upper points were Y = -0.049X + 3.675 (P < 0.05) and Y = -0.060X + 4.170 (P < 0.05), respectively. The stiffness at the upper point behaved statistically significantly differently to that at the lower point. Softening of the cervix at the upper point was significantly different between single pregnancies and twin pregnancies (P < 0.05), but no marked difference was noted between primiparous and multiparous women.

Conclusion: Cervical elastography using SWE was useful for measuring change in cervical stiffness during pregnancy, and the upper area of the cervix may be a more relevant assessment point for cervical softening than the lower area.

Keywords: cervical stiffness; elastography; pregnancy; shear-wave elastography; strain elastography.