Intraobserver and interobserver reliability of transvaginal cervical length measurements and quantitative ultrasound tissue characterization of the cervix in the second and third trimester of pregnancy.

PURPOSE: To determine the intraobserver and interobserver reliability of transvaginal ultrasound measurements of cervical length and quantitative ultrasonic tissue characterization (QUTC).

MATERIALS AND METHODS: 20 healthy women in the second and third trimester of pregnancy underwent transvaginal ultrasound examination of the cervix by two sonographers. 3 replicate vaginal measurements of cervical length and QUTC were taken by each observer for each woman. The repeatability coefficient and intraclass correlation coefficient as well as the interclass correlation coefficient and limits of agreement were calculated.

RESULTS: The reliability coefficient for transvaginal cervical length measurements was 0.95 for sonographer 1 and 0.99 for sonographer 2. The corresponding intraclass correlation coefficients for cervical length measurements were 0.872 and 0.973. The interclass correlation coefficient for transvaginal cervical length measurements was 0.986, the mean interobserver difference was -2 mm, and the limits of agreement were -5.4 mm to 1.5 mm. The reliability coefficients for QUTC were 0.90 (sonographer 1) and 0.97 (sonographer 2) and the corresponding intraclass correlation coefficients for cervical length measurements were 0.74 and 0.9. The interclass correlation coefficient was 0.56, the mean interobserver difference was 0.14, and the limits of agreement were -22.46 to 22.74.

CONCLUSION: Transvaginal cervical length measurements showed a high intraobserver and interobserver reliability, while quantitative ultrasonic tissue characterization had poor interobserver reliability and should currently not be applied in clinical practice.