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

 

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Zusammenfassung

Ziel: Bestimmung der Intra- und Interobserver-Reliabilität der transvaginalen Zervixlängenmessung und der quantitativen sonografischen Gewebetypisierung (QUTC). Material und Methoden: Bei 20 Frauen im zweiten und dritten Trimester wurde eine transvaginale Sonografie der Zervix von 2 Untersuchern mit jeweils 3 Untersuchungen pro Patientin durchgeführt. Zervixlänge und QUTC wurden bestimmt. Wiederholbarkeitskoeffizient, Intraclass-Korrelationskoeffizient und Interclass-Korrelationskoeffizient wurden berechnet sowie die Bland-Altman-Methode angewandt. Ergebnisse: Der Wiederholbarkeitskoeffizient für die transvaginale Zervixlängenmessung betrug 0,95 bei Untersucher 1 und 0,99 bei Untersucher 2. Die entsprechenden Intraclass-Korrelationskoeffizienten waren 0,872 und 0,973. Der Interclass-Korrelationskoeffizient für die Zervixlänge betrug 0,986 und die mittlere Interobserver-Differenz war –2 mm. Die Übereinstimmungsgrenzen nach der Bland-Altmann-Methode betrugen –5,4 mm bis 1,5 mm. Der Wiederholbarkeitskoeffizient für die QUTC betrug 0,90 bei Untersucher 1 und 0,97 bei Untersucher 2. Die entsprechenden Intraclass-Korrelationskoeffizienten waren 0,74 und 0,9. Der Interclass-Korrelationskoeffizient für QUTC betrug 0,56 und die mittlere Interobserver-Differenz war 0,14. Die Übereinstimmungsgrenzen nach der Bland-Altman-Methode waren weit und betrugen –22,46 bis 22,74. Schlussfolgerung: Die transvaginale Zervixlängenmessung zeigt eine hohe Intra- und Interobserver-Reliabilität. QUTC zeigt eine nur eine geringe Interobserver-Reliabilität und sollte daher gegenwärtig nicht im klinischen Alltag angewendet werden.

Abstract

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.

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Dr. Werner Stein

Klinik für Gynäkologie und Geburtshilfe, Universitätsmedizin

Robert-Koch-Straße 40

37075 Göttingen

Phone:  ++ 49/5 51/39 65 05

Fax:  ++ 49/5 51/39 65 61

Email: werner.stein@med.uni-goettingen.de