Measurement of endometrial thickness with transvaginal ultrasonography: is it reproducible?

To assess the intraobserver and interobserver variability of transvaginal ultrasonographic measurement of endometrial thickness, two investigators (M.V., M.-F. D.) independently evaluated two successive measurements in 55 patients with a 5.0 MHz transvaginal transducer. Each observer was blinded to his or her own and to the other's results. Measurements were taken at the maximal thickness in the longitudinal uterine axis. The intraclass coefficients evaluating the agreement between two measures of a same observer were 94% and 97%; the coefficient was 94% between the two investigators. Intraobserver kappa values (agreement on endometrium < or = 5 mm and > 5 mm) were 0.70 and 0.81, respectively; the interobserver kappa value was 0.74. Transvaginal sonographic measurement of endometrial thickness has excellent intraobserver and good interobserver agreement. However, in clinical practice, an endometrial thickness measuring +/- 1 mm of a cut-off value should be interpreted with caution, especially when this may modify the clinical management.