Does chemical composition have an influence on the fate of intraperitoneal gallstone in rat?

Perforation and spillage of gallstones is a common occurrence in laparoscopic cholecystectomies. The long-term complications of these stones remains controversial. Experimental studies have been carried out to elucidate the outcome of intraperitoneal gallstones, but the chemical composition of these stones has not been considered in previous studies. In this study, we investigated the local effects of intraperitoneal gallstones in rats with respect to their chemical composition. Bile and gallstones were taken from human cholecystectomy specimens, and sent for bacteriologic and chemical analysis. Twenty cholesterol and 10 pigment stones were placed in the abdominal cavity of rats. Long-term local effects of gallstones were determined at the end of 3 months with macroscopic and microscopic examination. The fragments of two pigment stones were infected by Staphylococcus aureus. Five (17%) cholesterol stones were found free in the abdominal cavity, and 25 stones (83%) were wrapped with adjacent structures. Granuloma formation was found around 4 pigment stones (13% of all stones, 40% of pigment stones; p = 0.0077). We observed large granulomas and cutaneous fistula formation in two rats with infected pigment stones placed in the abdominal cavity. Histhopathologic examination also showed significantly severe inflammatory reactions secondary to pigment stones (p<0.001). In conclusion our findings revealed that chemical composition has a significant influence on the fate of intraabdominal gallstones, and infection may aggravate local reactions and complications. Based on our findings, laparoscopic retrieval of spilled stones whenever possible seems to be useful to prevent subsequent infectious complications and inflammatory reactions. Patients with retained intraperitoneal pigment stones after laparoscopic cholecystectomy must be followed up closely.