Histologic characterization of vaginal vs. abdominal surgical wound healing in a rabbit model

We aimed to compare the histologic characteristics of vaginal vs. abdominal surgical wound healing in the rabbit. Bilateral 6 mm full-thickness circular segments were excised from the vagina and abdominal skin in 34 New Zealand white female rabbits. Animals were euthanized on the day of and 4, 7, 10, 14, 21, 28, and 35 days after wounding, and their wounds were evaluated using a modified scoring system. The inter- and intraobserver agreements of the scoring system were good (weighted kappa 0.63 and 0.71, respectively). A transient fibrinous crust was evident in 75% of the abdominal and in none of the vaginal wound specimens on days 4-7 after wounding (p=0.01). Acute inflammation peaked at day 4 in both the vaginal and abdominal wounds, while chronic inflammation peaked at days 4-7 and 14-21 in the abdomen and vagina, respectively. Both neovascularization and the amount of granulation tissue peaked at days 4 and 7 in the vagina and abdomen, respectively. Maturation of granulation tissue and collagen deposition increased persistently in both tissues until postwounding day 35. Reepithelialization increased after wounding, and was completed by day 14 in both tissues. The surgical wound-healing process in both the vagina and abdomen includes transient acute and chronic inflammation, fibroblast proliferation, and neovascularization, as well as progressive maturation of granulation tissue, reepithelialization, and collagen deposition. A transient fibrinous crust forms in the abdomen but not in the vagina 4-7 days after wounding. The modified histologic scoring system described here was found to be reliable and reproducible.