Cause of vaginal bleeding in postmenopausal women taking tibolone

To determine the cause of vaginal bleeding in postmenopausal women treated with tibolone.

Forty seven consecutive unselected women who bled in the course of treatment with tibolone between 1986 and 1995.

Clinical evaluation and pelvic ultrasound scanning in all women and additional Doppler flow assessment in 12. Hysteroscopy was performed in 20 women and D and C in nine.

An endometrial polyp was found responsible for the bleeding in 11 women and uterine fibroids in seven. Thickened endometrium was seen on ultrasound in six women; there was no histological abnormality in three of these women, two had benign simple hyperplasia and the remaining woman had an early carcinoma in situ. Carcinoma in situ was also found in another woman as an incidental finding in the endometrial curettings taken at hysteroscopy in the course of polypectomy. In over half, however, (24 women), no intrauterine cause could be found to account for vaginal bleeding. The occurrence of vaginal bleeding after tibolone clustered in two groups; 30 women who bled within 4 months of starting tibolone (of whom 17 had recently taken oestrogens) and 17 who bled after at least a years' therapy.

Bleeding after tibolone requires investigation. A morphological abnormality may be present even in women who have recently taken oestrogens and experienced cyclical bleeding. Despite full investigation, no cause for bleeding was however found in over half the group. The majority (37 women) of those who reported bleeding nevertheless continued on tibolone after completion of investigations with no recurrence of bleeding.