Repeatability and Reproducibility of Potential Ultrasonographic Bishop Score Parameters

Abstract

Determination of the Bishop score (BS) is a traditional method of assessing the cervix in obstetrics and gynecology. This examination is characterized by subjectivity of assessment and low repeatability. In scientific studies intended to evaluate the results of the procedure based on the initial assessment, it is necessary to find an objective scale based on ultrasonography. We selected five ultrasound parameters, measured with a transvaginal transducer, that are equivalent to the individual BS axes (dilatation assessed in three-dimensional ultrasound (DL), angle of progression (AoP), vagino-cervical angle (VCA), strain elastography using the E-Cervix module, and cervical length (CL)). All selected parameters were characterized by good to excellent repeatability (intraclass correlation coefficient (ICC) = 0.878–0.994) and reproducibility (ICC = 0.826–0.996). Each of the selected parameters significantly correlated with its corresponding BS axis. The highest value of the correlation coefficient was achieved with CL (−0.75) and DL (0.71). Other parameters were characterized by an average to high correlation (AoP and station = 0.69, hardness ratio and consistency = −0.33, position and VCA = −0.38). The best correlation with the sum of the BS points was exhibited by AoP (0.52) and CL (−0.61). The selected ultrasound parameters analogous to the BS axes were characterized by high repeatability and significant correlation with the axes of the original clinical BS. Further research into the predictive properties of a multivariate model based on these parameters is needed.