Improvement of diagnostic accuracy of transvaginal ultrasound for identification of endometrial malignancies by using cutoff level of endometrial thickness based on length of time since menopause.

Transvaginal ultrasonography (TVS) is considered useful for identifying endometrial malignancies, but it has a low specificity and a high false-positive rate. The purpose of this study was to improve the specificity of this technique. A total of 300 postmenopausal women were studied. They were clinically evaluated by TVS and endometrial histology. Twenty women yielded pathologic findings on endometrial examination. The mean endometrial thickness was related to the length of time since menopause. For endometria with pathological findings, sonographic measurements of endometria with a thickness of greater than 3 mm exhibited 95.0% sensitivity, 68.5% specificity, 19.4% positive predictive value, and 99.4% negative predictive value. If a 4-mm cutoff limit was used for < 5 years since menopause and a 3-mm cutoff limit was used for > or = 5 years since menopause, 95.0% sensitivity, 78.1% specificity, 25.7% positive predictive value, and 99.5% negative predictive value were obtained. The specificity and false-positive rate were improved when the cutoff limit was decided based on the length of time since menopause. The cutoff level of the endometrial thickness for detection of endometrial malignancies should be decided based on the length of time since menopause.