Impact of the uroperitoneum on the development of paralytic ileus: a preclinical study in the pig model

Purpose The intraperitoneal leak of urine is considered as a major cause of peritoneal inflammatory reaction that could lead to paralytic ileus. Our aim was to document the effect of urine on the peritoneal surface. Methods Seven white minipigs (one control-six tests) underwent standardized general anaesthesia. In three test pigs urine was aspirated from the bladder and instilled in the peritoneal cavity. In the remaining three pigs a continuous urine leak was created through section of the ureter. At 4 and 10 h laparoscopic harvesting of slices of the parietal peritoneum at the level of the Douglas pouch, lateral pelvic wall and subdiaphragmatic area was performed. Ileum slices were also obtained at 10 h. The slices were microscopically evaluated for inflammatory infiltrate (INI) of the peritoneum according to the Sydney system classification. Results The presence of urine in the peritoneum induces distention of the ileum. At 4 h, a light-moderate INI was observed to two pigs of both test groups but not to the control pig. At 10 h a light-moderate INI appeared in the peritoneal slices of the control pig. Moreover, three out of six pigs of both test groups showed some degree of INI of the parietal peritoneum. The histologic evaluation of the slices of the distended ileum did not reveal INI. Conclusions The intraperitoneal urine induces distention of the bowel but no inflammation of the visceral peritoneum in the short term (10 h). Other than inflammation mechanisms through which the urine induces small ileum distention should be investigated.