Endometrial assessment in women using tibolone or placebo: 1-year randomized trial and 2-year observational study

OBJECTIVE: To assess the effects of tibolone on the endometrium of postmenopausal women. DESIGN: A 1-year randomized, double-blind, placebo-controlled clinical trial and a 2-year open clinical trial. The placebo-controlled trial included 40 participants: 20 in the placebo group and 20 in the tibolone group; in the open trial, 17 participants receiving tibolone were assessed over 24 months. Transvaginal ultrasonography was carried out to assess endometrial thickness, and endometrial appearance was assessed on hysteroscopy. In addition, endometrial samples were submitted to histological examination. The occurrence of uterine bleeding and other adverse effects was also assessed. RESULTS: Results suggest that tibolone does not exert a stimulatory effect on the endometrium: unaltered endometrial thickness, atrophic appearance of most endometria on hysteroscopy, and endometrial histology classified as atrophic, hypotrophic with incipient secretion, or hypotrophic with weak proliferation (one case). Tibolone was effective in the treatment of climacteric symptoms, and only 8.7% of the participants presented uterine bleeding during treatment. CONCLUSIONS: Tibolone seems to be an effective option for the treatment of climacteric symptoms in postmenopausal women, especially in women who do not want to experience uterine bleeding again.