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.
There is interest in trying to reduce the morbidity from endometrial cancer through early detection, and there has been interest in using endovaginal ultrasound as a method to screen women to detect endometrial cancer.
In a prospective, observational study of 304 women using tamoxifen over 6 years, women underwent annual endovaginal ultrasound screening; women with abnormal ultrasound findings and women who were symptomatic with bleeding all underwent endometrial biopsy. Thirty-two percent of the ultrasound examinations had associated significant uterine abnormalities identified that required further medical or surgical investigation and treatment. However, most abnormalities (80%) represented benign polyps for which no treatment was needed. Six cases of primary endometrial cancer were detected, and all cases presented with irregular bleeding. The sensitivity of ultrasound was only 63.3%, with a specificity of 60.4%, and had a low positive predictive value for cancer of only 1%.
Other reports have noted similar results. Routine ultrasound surveillance in asymptomatic women using tamoxifen is not useful because of its low specificity and low positive predictive value. Evaluation of the endometrium in women taking tamoxifen should be limited to women symptomatic with vaginal bleeding.
Sonohysterography (hydrosonography) is a diagnostic test among asymptomatic women, and is able to separate space occupying endometrial lesions from an abnormal endometrial-myometrial junction in order to help guide biopsies. There is no evidence that routine screening sonohysterography will confer clinical benefit.