Diagnostic hysteroscopy in the mare - Uterine contamination and endometrial reaction

Abstract

Despite the fact that, nowadays, hysteroscopy is performed routinely, in equine gynecology, for diagnostic and minimally invasive surgical treatment, certain aspects should be considered in order to gain optimal conditions and results for the mare and for those carrying out the examination. These include thorough ascertainment of indication, careful uterine distension, choice of the correct stage of cycle and establishment of an adequate follow-up treatment and management. In order to monitor possible changes in the health of the genital tract following diagnostic hysteroscopy the clinical, microbiological (uterine swab) and pathohistological (endometrial biopsy) state of eight diestrous mares were examined before performance of a hysteroscopy, five days later and after the estrus which followed. Uterine distension was established by insufflation of filtered air. No follow-up treatment was carried out. At the outset all eight mares were clinically healthy, without evidence of pathogenic microbes in the uterine swabs or inflammatory alterations in the endometrial samples. Five days after hysteroscopy pathogenic microbes were detected in 50% of the mares (in three cases: slight amount of Pseudomonas aeruginosa, in one case: moderate amount of E.coli and slight amount of β-haemolytic Streptococcus). This last mare revealed a clinically discernable endometritis. Endometrial biopsy enabled a diagnosis of moderate, acute, superficial endometritis in this mare. A further five of the eight mares developed slight acute inflammatory endometrial reaction which was only detected through pathohistology, though only two of them showed the presence of pathogenic microbes. Following the subsequent estrus all mares were clinically healthy. In two mares Pseudomonas aeruginosa persisted, the others were not contaminated with pathogenic microbes. Two further mares still showed slight, acute, inflammatory endometrial reactions. A remarkable finding in the endometrial biopsies was the striking rise in the number of eosinocytes in the superficial layers of the endometrium five days after hysteroscopy, seen in six of eight mares. After the following estrus the number of eosinocytes was still obviously elevated in four mares. A contamination rate of 50% shows that a prevention of endometrial infection is indicated after hysteroscopy, for example through the infusion of mild antiseptic solutions into the uterus. Additional induction of estrus can advance uterine clearance. Independent of intrauterine contamination, 75% of the mares showed inflammatory endometrial reactions on pathohistology. It might therefore be recommendable not to use the following estrus for insemination. The aetiology of the endometrial eosinophilia following uterine distension through insufflation of filtered air is to date unknown. A correlation between poor vulvovestibular conformation and eosinophilic infiltration of the endometrium has been established by other authors in the past and a connection here seems likely.