Comparison of reliability between uterocervical angle and cervical length measurements by various experienced operators using transvaginal ultrasound

Purpose: To compare the reliability between uterocervical angle (UCA) and cervical length (CL) measurements by various experienced operators. Methods: Transvaginal ultrasonographies (TVS) were performed in 102 pregnant women between 16 degrees(/7)-24 degrees(/7) gestational weeks by different levels of experienced operators. For both CL and UCA measurements, intraobserver variability was assessed for each operator by examining the range between maximum and minimum measurements in each participant, compared to the mean of all three measurements. Interobserver variabilities were explored using Bland-Altman analysis. Intraclass correlation coefficients were used for both intraobserver and interobserver reliability. Results: For intraobserver variability of the UCA, the ranges between maximum and minimum UCA measurements in operator 1 and 3 were 1.5o-34o and 2o-36o (n = 51), and in operators 2 and 3 were 0o-61o and 1o-25o (n = 51). Intraclass correlation coefficients (ICC) for intraobserver reliability were 0.90 for operator 1, 0.67 for operator 2 and 0.93 for operator 3. For interobserver variability of the UCA, the limits of agreement for mean UCA were -37.53o-38.41o and -36.27o-26.17o, and for maximum UCA were -39.47o-41.38o and -44.24o-22.9o in comparisons between operators 1 and 3, and operator 2 and 3, respectively. Intraclass correlation coefficients for mean UCA were 0.73 and 0.74, and for maximum UCA were 0.71 and 0.67 in comparisons between operators 1 and 3, and operator 2 and 3, respectively. Conclusions: The UCA measurements had a higher intra- and interobserver reliabilities than the CL measurements.