Formation of a vesicovaginal fistula in a pig model

Validation of an ovine vesicovaginal fistula model

INTRODUCTION AND HYPOTHESIS

A representative, large animal model of vesicovaginal fistulas is needed for the training of surgeons and for the development of new surgical techniques and materials for obstetric fistula repair.

METHODS

The safety, feasibility, and reproducibility of vesicovaginal fistula creation were studied in 4 adult female sheep. A 1-cm fistula was created between the vagina and the bladder through a transvaginal approach. The defect was allowed to heal for 8 weeks and the animals were then euthanized. The primary outcome was the fistula patency. Secondary outcomes were fistula size, urogenital dimensions, urodynamic evaluation, histology (inflammation, vascularization, collagen deposition) and biomechanical characteristics of the fistula edge (stress at break, maximum elongation, and stiffness).

RESULTS

The transvaginal creation of a vesicovaginal fistula was safe. All animals survived the surgical procedure and follow-up period, without complications. Three of the four animals demonstrated a patent vesicovaginal fistula after 8 weeks. Baseline data are provided of the urogenital dimensions and the urodynamic, histological, and biomechanical characteristics of the model.

CONCLUSIONS

The ewe is a safe, feasible, and reproducible model for vesicovaginal fistulas. The model can help to study new techniques and materials to boost surgical innovation for vesicovaginal fistula repair.

Stable Gastric Pentadecapeptide BPC 157 Heals Established Vesicovaginal Fistula and Counteracts Stone Formation in Rats

With the stable gastric pentadecapeptide BPC 157 therapy known to heal various both external and internal rat fistulas, we attempt to approach vesicovaginal fistula, continuous urine leaking through vagina, bladder stones, and a possible therapy solution among rats with well-formed 2 week-fistulas (vaginal/vesical 4 mm large defects) started with delayed therapy. Subsequent control fistula course (the subsequent 1, 2, 4, and 6 weeks) since beginning revealed the failed healing, fistula leaking, adhesions, urinary leaking through vagina, failed epithelization, collagenization, granulation tissue and neovascularization, increased inflammation, and necrosis. Thereby, the later intervals revealed the persistent inability to sustain even minimal volume, vesical, and vaginal defects and stone formation at the end of the experiment (fistula-time day 56). BPC 157 therapy (10 µg/kg, 10 ng/kg, intraperitoneally once time daily or perorally in drinking water until sacrifice) was initiated with a considerable delay (at 2 weeks after fistula formation). Already within 1 week therapy, all BPC 157 regimens stopped urinary leaking through vagina, reversed the otherwise resistant poor healing course to the increased epithelization, collagenization, granulation tissue and neovascularization, decreased inflammation, and decreased necrosis. Thereby, at later intervals, all BPC 157 rats exhibited a five times larger volume that can be sustained before leaking as in healthy, vesical, and vaginal defects completely closed and no stone formation. Thus, macro/microscopic and functional recovery, and counteracted stone formation. Concluding, BPC 157 therapy’s beneficial effects resulted in healing and no stone formation, with µg- and ng-regimens, either given daily perorally in drinking water or intraperitoneally.