Endometrial thickness and histological abnormalities in women on hormonal replacement therapy: a transvaginal ultrasound/hysteroscopic study.

Abstract

The aim of this study was to assess if endometrial thickness could be used to select postmenopausal women on hormonal replacement therapy (HRT) at increased risk for endometrial abnormalities. The secondary aim was to assess if endometrial abnormalities were more likely to occur in patients with increased endometrial thickness or in patients with unexpected bleeding. Bi-endometrial thickness was measured by transvaginal ultrasound (TVS) in postmenopausal patients on sequential or combined HRT regimens. Women following a sequential regimen underwent TVS examination immediately after their withdrawal bleed, always between 5 and 10 days after the last progesterone tablet. A hysteroscopy with endometrial biopsy was performed within 5 days after the TVS examination, when endometrial thickness was > or = 4 mm, or when unscheduled bleeding was observed. A total of 190 women were recruited. In 138 women on sequential regimens, the mean value of endometrial thickness was 3.6 mm +/- 1.5, and in 52 women on combined regimens it was 3.2 mm +/- 1.8 (P = n.s.) Twenty-eight patients (15%) had an endometrial thickness > 4 mm, 35 patients (18.4%) reported unexpected bleeding. The percentage of abnormal endometrial findings (9%; three of 35) in patients selected for unscheduled bleeding was significantly lower than the percentage of abnormal findings in patients selected for hysteroscopy for endometrial thickness > 4 mm (36%; 10 of 28) (P < 0.01). All patients with unexpected bleeding and endometrial thickness < or = 4 mm (24 cases) were found to have an atrophic endometrium. Endometrial thickness in patients on sequential HRT, measured soon after withdrawal bleeding, is not significantly different from thickness measured in patients on combined HRT. Patients on HRT with an endometrial thickness of > 4 mm could be considered for histological sampling. The prevalence of abnormal endometrial findings in patients with a thick endometrium is significantly higher than the prevalence observed in patients with unexpected bleeding.