Intrapartum measurement of cervical dilatation using translabial 3-dimensional ultrasonography: Correlation with digital examination and interobserver and intraobserver agreement assessment

Objective. The purpose of this study was to determine the accuracy and reproducibility of intrapartum translabial 3-dimensional (3D) ultrasonographic measurements of cervical dilatation during labor. Methods. A prospective observational study was conducted. Three-dimensional ultrasonographic volume data sets from 52 patients were collected during labor and stored. Later, all volumes were randomly reviewed twice offline by 2 examiners blinded to previous clinical and ultrasonographic measurements. The correlation with delivery room personnel digital vaginal examinations and interobserver and intraobserver agreement were determined. Results. Twenty-four patients were examined during the latent phase (0- to 4-cm cervical dilatation), and 28 patients were examined during the active phase (5- to 10-cm cervical dilatation). Translabial 3D ultrasonographic measurements of the cervical mean and maximal diameters and inner cervical area showed a positive correlation with digital vaginal examinations (r² = 0.609, 0.587, and 0.469, respectively; all P < .001). The interobserver mean differences ± SD between paired measurements for the mean and maximal cervical dilatation and inner cervical area were 0.11 ± 0.49 cm, 0.12 ± 0.48 cm, and -0.22 ± 5.69 cm², and the intraclass correlation coefficients (ICCs) were 0.82, 0.85, and 0.87. The intraobserver mean differences between paired measurements of the mean and maximal cervical dilatation and inner cervical area were 0.002 ± 1.15 cm, 0.02 ± 1.4 cm, and -0.41 ± 1.15 cm², and the ICCs were 0.85, 0.79, and 0.75. Conclusions. Assessment of cervical dilatation using 3D ultrasonography during labor is feasible and reproducible.