Long term effects of tibolone on the genital tract in postmenopausal women

To assess the effects of six years tibolone therapy on the genital tract in postmenopausal women against matched voluntary controls.

Prospective, non-randomised, open label study of the efficacy of tibolone.

Symptoms were assessed by questionnaires every six months. Assessment of genital tract cellular activity comprised annual vaginal smear and endometrial biopsy/smear in the tibolone group (n = 58) and vaginal smear alone in the control group (n = 55). As a recent protocol addition, transvaginal ultrasound assessment of endometrial thickness was performed in all women who gave consent. Endometrial biopsy was performed in control women if the endometrial thickness was > 5 mm. Karyopyknotic index and maturation index were calculated from the vaginal smears.

The rate of amenorrhoea between six months and six years treatment was 90% in the tibolone group compared with 91% in the controls (P was not significant). There was improvement in reported vaginal symptomatology in the treatment group but not in the controls. Median endometrial thickness increased slightly in the tibolone treated group (3.2 mm tibolone vs 2.5 mm control; P < 0.05). There were no cases of cytologically proven endometrial stimulation in asymptomatic women in either group. Both vaginal karyopyknotic index and maturation index increased significantly in the tibolone treated group over six years, but not in the control group.

Tibolone is effective at maintaining an inactive endometrium while providing oestrogenisation of the lower genital tract over a six year period.