Differences between the pre-menopausal and post-menopausal uterine fibroid vasculature

: To quantitatively examine differences in microvascular density between fibroid and myometrial tissue from fibroid uteri removed at hysterectomy, both before and after the menopause, and with hormone replacement therapy. : Factor VIII immunostaining of formalin fixed tissues was used to identify blood vessels, and the vessels counted by an investigator blinded to tissue type or menopausal status. : The mean myometrial: fibroid MVD ratio was 2.38 higher in the post-menopausal group (95% CI: 0.12, 4.65, p = 0.0474) than in the pre-menopausal group, with the hormone therapy (HT)-using post-menopausal group lying in between. An increase in microvascular density in the myometrium after the menopause was responsible for most of the change in ratios seen between the pre and post-menopausal pairs. There was a trend to increasing myometrial MVD with increasing number of years post-menopause. : Myometrial microvascular density increases markedly after the menopause, while fibroid microvascular density does not alter. Thus, the difference between myometrial and fibroid vasculature becomes greater after the menopause. The implications of this for the treatment of fibroids in post-menopausal women is discussed.