Uterine endometrial fissures
Key words: bovine, endometrium, fissures, uterus, postpartum, pyometraThe opened uterus shown below (image 1) was obtained from a seven-year-old Holstein cow in poor body condition. She was euthanized and submitted for postmortem examination because of infertility and continual loss of weight. Her history of postpartum estrous cycles was unknown.
Image 1, size available: 2005 x 1350 px
Apart from mild subacute suppurative broncopneumonia, the most noticeable feature in this cow was her moderately enlarged uterus, especially the right uterine horn. The uterus was turgid and distended with a large volume (perhaps 2 liters) of cloudy, tan colored, watery pus. The cervix was closed, not allowing any passage of the purulent material into the vagina.
It is possible that pyometra had been supported by a corpus luteum (CL) formed from a postpartum ovulation (the common situation in pyometra) because a corpus albicans (CA) was present in her left ovary. However, the CA formed from the regression the CL of pregnancy can persist for extended periods after calving so that possibility is questionable. Therefore and most likely, one is left with the remarkable situation where the cervix was closed as is the case in common pyometra, yet there was an absence of luteal tissue to support that condition. More remarkable however, were the multifocal deep fissure-like ulcerations on the endometrium (image 2). These are shown, partially covered by purulent exudate in the right half of the image above. The largest of these measured 2 cm at its widest point.
Image 2, size available: 3005 x 1773px
As indicated by the yellow arrows in the image above, the fissures were visible from the peritoneal surface as well. The serosal surface of the uterus was covered with a fine layer of yellowish fibrin indication an extension to local peritonitis.
Histopathology showed multiple small abscesses within these fissures. Neutrophils were the predominant cell type, accompanied by a low population of mononuclear cells. Culture of the uterine exudate produced no microbial growth; not particularly rare in a purulent environment.
Fissures such as these are not characteristic of common cases of pyometra due to Trueperella pyogenes (formally assigned successively to the the genera Corynebacterium, Actinomyces, then Arcanobacter). Despite an interest in reproductive pathology spanning many years, this author is unaware of similar cases and solicits the input of colleagues in this regard. Certainly, partial circumferential-splitting of the endometrium is a feature usually not seen in pyometra, even in uteruses distended with large volumes of pus.
