Factors that may increase morbidity in a model of intra-abdominal contamination caused by gallstones lost in the peritoneal cavity.

Objective: To assess the effect of intraperitoneal gallstones with and without Escherichia coli and sterile bile on the incidence of intraperitoneal complications in mice.

Design: Prospective randomised study.

Setting: Teaching hospital, Turkey.

Material: 180 Swiss albino mice in five groups, n = 20 in the control group, and n = 40 in each of the experimental groups.

Interventions: Group A laparotomy alone (controls); group B, laparotomy amd intraperitoneal instillation of E. coli 4 x 10(6) 0.1 ml; group C, laparotomy and insertion of sterilised gallstones; group D, laparotomy, insertion of gallstones and instillation of E. coli 4 x 10(6) 0.1 ml; and group E, laparotomy, insertion of gallstones, and instillation of E. coli 4 x 10(6) 0.1 ml and sterile bile 0.1 ml. A quarter of each group was killed after 1, 2, 4, and 8 weeks.

Main outcome measures: Intra-peritoneal abscesses, adhesions, perforations, fistula, or obstruction.

Results: No mice died. Adhesions were found in 3(15%), 7(18%), 30(75%), 25(63%), and 24(60%) in the five groups, respectively. No mice in groups A, B, or C developed an abscess, but 8 did in each of groups D and E (20%). One mouse in group D developed obstruction. Logistic regression showed that abscess formation was significantly increased by the addition of gallstones and E. coli to the peritoneal cavity (p < 0.001) but the addition of bile had no effect. Gallstones increased the rate of adhesions more than nine fold (p < 0.001) but E. coli with or without bile had no effect (p = 0.75).

Conclusions: Free gallstones within the peritoneal cavity with or without E. coli or sterile bile, or both, increased the rate of formation of both abscesses and adhesions in mice. These results suggest that efforts should be made retrieve gallstones that are dropped into the peritoneal cavity during laparoscopic cholecystectomy, particularly in patients with acute cholecystitis.