Structural arrangement of vesicouterine fistula revisited: An immunohistochemical study documenting the presence of the endometrium.

Previous research has described a woman of reproductive age who presented with a vesicouterine fistula (VUF) of 20 months' duration. The VUF was lined with a metaplastic glandular epithelium containing both estrogen receptors (ER) and progesterone receptors (PR) in abundance. The aim of the present investigation was to evaluate the histology of the VUF canal when exposure to urine of the cellular elements within the fistula was of much shorter duration. A 41-year-old woman who developed a VUF during her third cesarean section was treated with transvesical fistula excision, electrocoagulation, and subsequent attempted hormonal treatment. Later, the patient underwent open surgery fistula repair. Postoperative specimens were subjected to anatomopathological examination together with immunohistochemical staining for ER and PR using monoclonal anti-human antibodies. Herein, we present for the first time detailed microscopic evidence that, at two separate timepoints, the fistulous tract was lined with the endometrium, which covered approximately 80% of the length of the VUF canal. In its intermediate segment, the urothelium formed an additional layer on the surface of the endometrium. At both timepoints, in the columnar epithelial and stromal endometrial cells lining the fistula, both ER and PR were present in abundance. In conclusion, VUF in subjects of reproductive age fulfill criteria for endometriosis. This study provides a rationale for the conservative treatment of VUF consistent with the hormonal treatment of endometriosis.