Intra-peritoneal Povidone-iodine Irrigation Decreases Abscesses in a Perforated Appendicitis Murine Model

Background: Children with perforated appendicitis frequently form post-operative intra-abdominal abscesses (IAA). Intra-peritoneal irrigation for prevention remains controversial. Using a perforated appendicitis murine model, we sought to determine the effect of intra-peritoneal irrigation on post-operative IAA and adhesion formation.

Methods: A survival operation was performed where cecal ligation and puncture was used to simulate perforated appendicitis. After 72 h, mice underwent a second operation where a distal cecectomy and intra-peritoneal irrigation was performed. Mice were assigned to a no irrigation group or one of four irrigation groups: normal saline, povidone-iodine (PVI), tacrolimus, or PVI followed by tacrolimus. At 2-weeks or 2-months after the second survival operation, mice were euthanized and IAAs were counted, measured, and cultured. Intra-peritoneal adhesion severity was graded on a 4-point scale. Statistical analysis compared IAA numbers and adhesion grade between the irrigation groups.

Results: In the 2-week cohort, prevalence of IAA was 78 % (n = 129). Type of irrigation solution was associated with abscess development (p < 0.001). Pairwise comparisons demonstrated PVI alone decreased abscess count. PVI irrigation caused more severe adhesions while tacrolimus decreased adhesions and adhesion grade was dependent on irrigation solution (p < 0.001). In the 2-month cohort, similar responses were observed with decreased abscess numbers in the PVI group (p = 0.006) but increased adhesion burden (p = 0.002).

Conclusion: Povidone-iodine irrigation decreases intra-abdominal abscess formation, but increases adhesion formation.