Influence of Omentectomy on Peritoneal Defense Mechanisms in an Experimental Model of Intra-Abdominal Infection

Abstract

Background/Aim: The omentum has an important role as part of peritoneal defense mechanisms. The aim of this study is to show the bactericidal activity of peritoneal fluid and the role of the omentum as a peritoneal defense mechanism in experimental animals with intra-abdominal infections. Methods: 40 male Spraque-Dawley rats weighing between 250 and 300 g were used in this study. The rats were randomly divided into four groups consisting of 10 animals. The operative procedures were done under sterile conditions. In group I sham laparotomy was done. In group II, the distal part of the cecum was ligated, and cecum perforation was performed. In group III, total omentectomy was performed after cecal ligation and perforation. In group IV only omentectomy was performed. Baseline and 2- and 4-hour peritoneal fluid samples were taken using a Pasteur pipette during laparotomy under anesthesia. Total peritoneal cells counts, bactericidal activity of peritoneal fluid, and types of phagocytic cells in the peritoneal fluid were assessed. Results: As compared with baseline values, the total peritoneal cell counts were increased at the 2nd and 4th h in all groups (p < 0.05). A significant increase was observed after 4 h as compared with 2 h in sham laparotomy, cecal ligation+perforation+omentectomy, and omentectomy groups (p < 0.05). A significant increase in the cell counts after 2 h was found in the other groups when compared to the sham laparotomy group (p = 0.0001). After 4 h, there was a significant difference between the groups, but especially prominent in the cecum ligation+perforation+omentectomy group (p = 0.0001). Proliferating colony counts of Escherichiacoli and Pseudomonas aeruginosa decreased after 2 h, and there was no proliferation in the subsequent cultures. It was observed that the macrophage counts significantly increased after 2 and 4 h as compared with baseline in intragroup assessments (p = 0.0001). In the intergroup assessment, an increase was observed in the macrophage counts at baseline and after 2 and 4 h, and this was significant in the cecal ligation+perforation+omentectomy group (p = 0.0001). In the omentectomy group, a significant decrease was observed in the macrophage counts between the 2nd and 4th h (p = 0.0001). Conclusion: Removal of the omentum in the presence of intra-abdominal infections causes the peripherally derived macrophages to take over the defensive role of macrophages of peritoneal origin as a compensatory mechanism, thus the peritoneal bactericidal activity against E. coli, the major pathogen in intra-abdominal infections, does not change after omentectomy.

Role of omentectomy as part of radical surgery for gastric cancer

“…Several studies have shown no survival difference between partial and complete omentectomy as part of radical gastrectomy for gastric cancer. A retrospective study in 196 patients found no difference in 3‐ and 5‐year relapse‐free survival in patients in whom omentectomy was performed as part of radical gastrectomy compared with those in whom omentum‐preserving gastrectomy was undertaken.…”

“…The greater omentum is the primary peritoneal defence organ responsible for the clearance of bacteria from the peritoneal cavity. The greater omentum reduces intestinal adhesions, not only by interposing between the abdominal viscera and the abdominal wall to create a mechanical barrier, but also because its mesenchymal cells produce fibrinolytic factors. Notably, high‐quality evidence for a survival benefit of complete omentectomy is lacking; retrospective studies have shown no difference between omentectomy compared with omentum‐preserving strategies.…”

A Prospective Randomized Study Comparing Patients with Morbid Obesity Submitted to Laparotomic Gastric Bypass with or without Omentectomy

“…Therefore, the peritoneal bacterial activity against Escherichia coli does not change after omentectomy. Finally, in a case report of an obese patient with multiple rib fractures and increased abdominal pressure, omentectomy allowed to perform successful weaning from mechanical ventilation [15]. With all these eventual beneficial aspects of omentectomy in morbidly obese patients, the question is: why is this not a routine surgical step when performing any type of bariatric surgery?…”

The Omentum: Anatomical, Metabolic, and Surgical Aspects

“…73 In rodent models, however, omentectomy does not decrease the bactericidal activity of peritoneal fluid, 74 nor does it increase bacterial counts in a model of cecal perforation. 75 The same group looked at the effect of omentectomy on the inflammatory phase of anastomotic healing and found that there was no difference between rats subjected to omentectomy. 76 In fact, they showed that following omentectomy, systemic compensatory mechanisms lead to the recruitment of peripheral leukocytes which mediate the healing process.…”