The advantages of using cytospins of uterine lavage fluid for the diagnosis of equine endometritis

Uterine lavage (UL) is a routine diagnostic procedure for endometritis. In UL the fluid is centrifuged and the sediment smeared. Samples prepared in cytocentrifuges, the so-called “cytospins”, are useful for evaluating cells in fluids, but never been used in UL. The aim of this study was to assess the usefulness of cytospins after UL, comparing automatic versus manual cytocentrifuges, and to determine their value for the diagnosis of endometritis. The study was divided in two parts. Firstly, UL was performed in 16 mares and a small part of the retrieved fluid was cytocentrifuged in an automatic (PreCyto) and manual (PreMan) cytocentrifuge, whereas the remaining fluid was centrifuged. After that, the sediment was divided into three quotas. One quota was smeared, one was processed in an automatic cytocentrifuge (PostCyto) and the last quota was cytospinned in a manual apparatus (PostMan). Cytospins obtained were scored for cellularity, cell preservation, presence of inflammatory cells, bacteria and contaminants; results were compared with sediment smears. Secondly in this study, the best cytospin method was compared with sediment smears in another group of 13 mares, which had endometrial biopsy after UL. Agreement between sediment smears and cytospins was poor to moderate. Compared to sediment smears, cytospins were more cellular, with better morphological details. Urine crystals and fecal contamination were detected more often in cytospins (especially PostCyto and PostMan). No differences in the percentage of inflammatory or epithelial cells existed. PostMan was considered the best method to evaluate UL fluid and it had higher sensitivity (80%), compared with sediment smears (60%), for diagnosing endometritis. Cytocentrifugation offers significant advantages over sediment smears and the manual cytocentrifuge is well suited for horse stable conditions.