Mechanical and histopathological evaluation of a novel foldable-anvil circular stapler in colonic anastomosis: a randomized preclinical study

To evaluate the mechanical and histopathological performance of a novel circular stapler incorporating a foldable-anvil mechanism in a rabbit model of colonic anastomosis and to compare its outcomes with those of a conventional circular stapler. Twelve adult female New Zealand White rabbits were randomized to either a conventional circular stapler (control, n = 6) or foldable-anvil stapler group ( n = 6). Anastomotic burst pressure and histopathological parameters were assessed on postoperative day 5. Between-group comparisons were performed using two-sided exact Mann–Whitney-based analyses, and histopathological outcomes were considered exploratory. Ten of 12 randomized animals completed the protocol ( n = 5 per group); one control animal died during anesthetic induction, and one foldable-anvil animal underwent early euthanasia following colonic wall injury during device insertion. Mean burst pressures were 227.4 ± 22.6 vs. 209.8 ± 14.4 cmH₂O (exact p = 0.1508). Median collagen scores were 1.0 vs. 3.0 (exact p = 0.0079; Holm-adjusted p = 0.0952). No other histopathological parameter differed significantly between the groups. No statistically detectable between-group difference in day 5 burst pressure was observed. The collagen finding was exploratory and did not remain significant after multiplicity adjustment. Given the small sample size, the findings do not establish equivalence, non-inferiority, or comparative safety.