Laparoscopic Lavage Predominantly Reduces Peritoneal Inflammatory Proteins, Consistent With Washout

INTRODUCTION: Laparoscopic lavage is a treatment option for selected patients with perforated diverticulitis and purulent peritonitis, but the mechanism of action remains unclear. Whether its effect is driven primarily by mechanical washout or by procedural factors remains unknown. This experimental study aimed to determine the relative contribution of lavage and procedural factors to the early peritoneal inflammatory response. METHODS: In a randomized, controlled, experimental study, 124 rats underwent sham laparotomy or cecal ligation and puncture-induced peritonitis followed by predefined interventions varying lavage, insufflation gas (carbon dioxide versus helium), lavage fluid (saline versus buffered solution), and intra-abdominal pressure (2 versus 8 mmHg). Peritoneal fluid and serum were analyzed 1 h postintervention using a 92-protein inflammatory panel. Proteomic patterns were assessed by principal component analysis and differential protein abundance using mixed linear models. RESULTS: Peritoneal inflammatory protein profiles separated clearly between lavaged and nonlavaged animals, with no consistent effect of insufflation gas, lavage fluid, or intra-abdominal pressure. Lavage was associated with reduced inflammatory protein levels in peritoneal fluid, including cytokines, chemokines, and growth factor signaling proteins, whereas only a few proteins increased. In serum, no corresponding separation in protein profiles was observed between experimental groups. CONCLUSIONS: Lavage was the primary contributor to reduced peritoneal inflammatory protein levels, with no clear effect of procedural factors. These findings are most consistent with mechanical clearance and dilution as the primary explanations for the observed reduction in peritoneal inflammatory protein levels and support further investigation of lavage volume as a potentially important factor in the clinical setting.