Ultrasonography in women without vaginal bleeding
A comparison of TVU and endometrial aspiration was conducted among asymptomatic postmenopausal women potentially eligible for an osteoporosis prevention trial  as part of determination of eligibility for randomization. TVU was performed on 1,926 women. Of these, 93 women had ET greater than 6 mm. Among the 93 women with abnormal ET, 42 had endometrial aspiration with one finding of abnormal pathology (defined as adenocarcinoma or atypical hyperplasia). Of the 1,833 women with ET measuring 6 mm or less, 1,750 women had endometrial aspiration and five of these women had an abnormal pathologic biopsy. Among this population of asymptomatic postmenopausal women, the estimated sensitivity for TVU with a threshold value of 6 mm was 17% and 33% for a threshold value of 5 mm.
One study assessed the usefulness of TVU among a cohort of postmenopausal, asymptomatic women receiving hormone therapy. Utilizing the Postmenopausal Estrogen and Progestin Interventions Trial participants who had undergone both TVU and endometrial biopsy, sensitivity, specificity, positive predictive value, and negative predictive value were determined for women who received placebo, estrogen alone, and estrogen-progestin therapy. At a threshold value of 5 mm for ET, TVU had 90% sensitivity and 48% specificity. Using this threshold, more than half the women would receive a biopsy while only 4% of them had serious disease.
Another study obtained endometrial biopsy specimens from 801 asymptomatic perimenopausal and postmenopausal women prior to enrollment in a hormone therapy study. Of the specimens, 75% of the samples contained sufficient tissue for diagnosis. Among these women, one case of endometrial cancer was diagnosed, illustrating the low yield of screening among asymptomatic women and the difficulty with endometrial cavity access.
Although TVU can be used to evaluate asymptomatic and occult endometrial pathology, the technique has not been evaluated as a screening method for reducing mortality in asymptomatic women.
Ultrasonography in women using tamoxifen
Tamoxifen is widely used as part of adjuvant therapy for breast cancer and as chemoprevention for women at increased risk of breast cancer. In addition to the protective effects for breast cancer, the biological and endocrine effects of tamoxifen increase patients' risk of developing endometrial pathology, including endometrial polyps, endometrial hyperplasia, and endometrial carcinoma.