Objective: Compare transvaginal uterine ultrasound and endometrial biopsy in evaluating the endometrium of postmenopausal women who are taking estrogen replacement therapy (ERT) or hormone replacement therapy (HRT; estrogen and progestin).
Design: Prospective multicenter study done in the United States with 148 healthy women with an intact uterus. A total of 121 women used hormonal preparations prescribed by personal physicians. Continuous combined HRT regimens, nonoral forms of ERT or HRT, and intrauterine devices were not allowed for 3 months before the study began. Endometrial biopsy samples were taken within 3 days of transvaginal ultrasound measurement. The uterus was scanned transversely and longitudinally. Endometrial thickness was measured at the thickest part of the longitudinal plane.
Results: Endometrial thickness ranged from 1.0 to 25.0 mm. The range in 126 women with a normal endometrium (determined by diagnoses of endometrial biopsies) was 1.0-25.0 mm (median, 5.0 mm); in 15 women with an abnormal endometrium, the range was 2.8-23.0 mm (median, 6.2 mm). A significant difference (p = 0.006) in endometrial thickness was seen between the 38 subjects taking ERT and HRT (median, 6.1 mm) with unexpected bleeding or spotting and the 26 untreated women in the control group (median, 4.0 mm). Overall, results were clinically inconclusive.
Conclusions: Results of ultrasound as a screening technique in postmenopausal women who were taking ERT or HRT did not correlate well with results of endometrial biopsy. Unscheduled bleeding in postmenopausal women should be investigated regardless of results of ultrasonographically determined endometrial thickness. Abnormalities may be found with an endometrial thickness of less than 4 mm with or without HRT and even with no bleeding.