Identification of vessel degeneration and endometrosis in the equine endometrium, using narrow-band imaging hysteroscopy

In this study, endometrosis and angiosclerosis in mares were studied. Endometrosis is a severe, progressive, and irreversible fibrotic condition that affects the endometrium, whereas angiosclerosis refers to thickening of vessel walls due to degenerative changes leading to reduced elasticity of the walls and lower perfusion. Histologic evaluations were performed on biopsies and compared with vascular features of the endometrial surface obtained via narrow-band imaging (NBI) hysteroscopy. First, it was determined if hysteroscopic evaluation of the endometrium using NBI resulted in a better visualization of the vascular pattern (i.e., vessel-versus-background contrast was increased) compared with using white light. This was found to be the case for examinations in vivo (n = 10), but not when using abattoir uteri (n = 3). In the second part of this study, it was determined if vascular densities and sizes as derived from NBI images could be used as indicators for the degree of degenerative changes of the equine endometrium and its vessels. Narrow-band imaging hysteroscopic evaluations were performed (n = 10), and endometrial biopsies (n = 32) were collected. Histologic specimens were evaluated for degree of endometrosis and angiosclerosis, and they were classified in Kenney categories. Narrow-band imaging images were analyzed for vascular pattern. Samples classified to Kenney category I, or without signs of vessel degeneration, had significantly higher vascular densities than samples from Kenney category IIa or with angiosclerosis. In conclusion, narrow-band imaging facilitates enhanced visualization of the vasculature of the equine endometrium during hysteroscopies, which has applications in detection of endometrosis and angiosclerosis.