Anatomy, visualization and sampling of the biliary tree in animals and man

Difficulties in obtaining proper bile samples are due to inaccessibility of the biliary tree and to distortions induced by sampling methods. One must be cognizant of the effects of diet on bile secretion and gallbladder motility. Experimental methods which interrupt the enterohepatic circulation or alter the intestinal migrating myoelectric complex induce spurious changes in bile flow and composition. Biliary tract pressure-flow relationships must be maintained or the gallbladder will be made functionless. Dead space errors lead to distortions unless studies are performed in the steady state, or dead space is measured and corrections are applied. Surgery has major effects on some parameters of interest, and animals should be allowed to recover when these are studied. The effect of the mixing of bile with other secretions in the duodenum must be considered when using bile-rich duodenal fluid. For some parameters of bile secretion, mixing is unimportant but for others, special precautions for handling bile and interpreting results are required.