Formation and fate of fibrin clots in the biliary tract: a clinical and experimental study.

Fibrin clots may form in the biliary tract from hemobilia or in inflammatory disease. There is a wide variation in the clinical course of such clots which is exemplified by 9 patients. They may either dissolve through fibrinolysis, get ejected into the intestine, remain and obstruct the biliary tract, or may even transform into gallstones. In order to elucidate the mechanisms involved, the behavior of blood clots in bile was studied in vitro. A model was constructed of the biliary tract and, drained by a T-tube, where human bile circulated with a flow rate resembling that in vivo. When a small amount of human blood was injected, it flowed immiscibly to the lowest level, displaced the bile, and formed a clot of pure blood. Even a minor bleeding may thus form a coagulum. This is different from the mixed clot of blood and bile that forms in experiments simulating major hemorrhage. These findings are related to clinical experience and especially to the disappearance of "retained stones" with or without the use of dissolving agents.