Effect of aerosolized fibrin solution on intraperitoneal contamination. The potential deleterious effects of aerosolized fibrin on contaminated procedures were investigated in a rat model of peritonitis. One hundred forty rats were divided into two groups. In the control group, gelatin capsules containing feces (10(7) bacteria per milliliter) and barium sulfate at various dilutions were placed into the abdomen; in the second experimental group, a solution of cryoprecipitate, thrombin, and calcium was sprayed diffusely into the peritoneal cavity after similar fecal contamination. Fecal inocula with low bacterial concentrations (0.01, 0.1, and 0.15 mL) caused few deaths from peritonitis or abscess formation in either group. Heavy peritoneal contamination (0.25, 0.3, and 0.5 mL) caused early deaths from peritonitis in both groups, with 80% of the deaths due to sepsis in the first 48 hours. However, in the moderately contaminated rats (0.2 mL of fecal inoculate), fibrin aerosol reduced the 10-day mortality from 80% to 10%. In all survivors in the fibrin-treated group, intraperitoneal abscesses developed. With intraperitoneal bacterial concentrations of 2 x 10(6) organisms, early acute mortality from fibrinopurulent peritonitis is decreased at the expense of late, localized, nonlethal abscess formation. Aerosolized fibrin solution must be used with caution in contaminated surgery. 