Normal saline may promote formation of peritoneal adhesions

Background: Normal saline is commonly used for rinsing the abdominal cavity and many surgeons claim that it is not harmful to peritoneum. We found in patients treated with laparoscopic surgery, that mean 25% of the instilled fluid is not drained and dwells in the abdominal cavity. Therefore we evaluated changes of the saline biocompatibility during its dwell in the rats abdominal cavity. Methods: In 10 anesthetized rats normal saline were instilled into the abdominal cavity and samples of the dwelling solution were collected every 30 minutes, for 4 hours. Inflammatory parameters and effect of the collected samples on in vitro cultured rats mesothelial cells were studied. Results: Low pH of the saline was normalized, but number of cells and % of macrophages and eosinophils, as well as elastase activity and MCP-1 and TGF-β concentration increased, proportionally to the dwell time. Fluid samples tested ex-vivo suppressed proliferation of the mesothelial cells and induced biphasic (stimulation/inhibition) effect on synthesis of MCP-1 in these cells. Similar pattern of release was observed for TF, whereas synthesis of t-PA in the mesothelial cells was strongly suppressed. Conclusions: Mesothelial cells exposed in vivo to normal saline dwelling in the abdominal cavity acquire properties which may accelerate formation of the peritoneal adhesions.