Changes in endometrial blood vessels in the endometrium of women with hormone replacement therapy-related irregular bleeding

Abstract

Background: Irregular bleeding affects up to 60% of hormone replacement therapy (HRT) users. The mechanism of this bleeding is not understood. Reduced endometrial microvascular integrity appears to underlie breakthrough bleeding in pre-menopausal women and the aim of this study was to establish whether similar changes are seen in HRT users and hence to elucidate a possible mechanism of irregular bleeding. Methods: Endometrium from 34 HRT users with amenorrhoea, irregular bleeding or regular bleeding was assessed for endometrial endothelial cell density (anti-CD34), number of blood vessels per mm2, vascular basal lamina components (laminin, collagen IV and heparan sulphate proteoglycan) and i..