Findings in uterine biopsies obtained by laparotomy from bitches with unexplained infertility or pregnancy loss: an observational study

Surgical uterine biopsies (SUBs) were obtained by laparotomy from 14 bitches with unexplained infertility whose pregnancy was not confirmed (NCP group) and from 7 bitches that had experienced unexplained pregnancy loss (PL). SUBs were obtained during the luteal phase of the cycle in 16 of 21 bitches. Overall, the biopsied uterine tissues presented obvious alterations in 17 of 21 cases. In the NCP group, 11 of 14 bitches had varying degrees of uterine lesions. In this group, six of nine bitches with macroscopically normal uteri presented histopathologic changes in the endometrium. All bitches with macroscopic modifications (five of 14) presented endometrial changes. Cytologic examination of the uterine fluid revealed eosinophilic amorphous material, erythrocytes, and a low number of degenerated leukocytes. On histopathologic examination, the most common lesion was fibrosis with degeneration of the endometrial glands (FDEGs six of 11), followed by endometritis (four of 11), cystic endometrial hyperplasia (CEH) (two of 11) and pseudoplacentational endometrial hyperplasia (PEH) (two of 11). Other lesions were adenomyosis, mucometra, and an endometrial polyp (one each of 11). Mixed lesions were present in four of the 11 bitches. In the PL group, macroscopic modifications consisted of intraluminal uterine dilatation (seven of seven) and presence of ovarian cysts (three of 7). Cytologic examination of the uterine content revealed high leukocyte counts. Histopathologic endometrial changes were found in six of seven bitches and included endometritis (three of seven), PEH (two of 6), pyometra (one of six), and CEH together with mucometra (one of six). Research of infectious agents was performed in 20 of 21 cases. Surprisingly, no bacteria or viruses were isolated from the uterine lumen in any of the cases. When the SUB was performed in diestrus, a medical treatment with aglepristone or with prostaglandins was established to avoid the risk of postoperative-induced pyometra. One case of complete uterine stenosis was the only side effect observed in the bitches that were not ovariohysterectomized after the collection of a biopsy (17 of 21). In conclusion, the most common findings in our biopsy specimens were FDEGs, endometritis, and hyperplastic remodeling of the endometrium (CEH and PEH). SUBs might provide useful information regarding the cause of infertility or PL. This technique allows visual inspection and palpation of the whole uterus and ovaries before the selection of a precise site for the biopsy. The size of the tissue sample collected can be large enough for an accurate diagnosis and samples for research of infectious agents can be obtained with no risk of contamination. Risk of side effects seems low when SUBs are performed according to this protocol, including postsurgery treatment with aglepristone or prostaglandins.