The susceptibility of the gallbladder and extrahepatic ducts to overdistention or inflammation from cholelithiasis makes these structures a common source of referred visceral pain. The utilization of the biliary passages in animals in the study of visceral pain has brought forth information of great value but is limited, as are all experiments involving pain in animals, because of the great barrier of speech. I have mechanically distended these passages in conscious patients at the time of operation in an effort to make observations on the important mechanism of referred visceral pain and determine whether a difference existed in the radiation and type of pain with distention of the gallbladder as compared to the common duct.
Why should patients with cholelithiasis have pain in the epigastrium, right upper quadrant or left upper quadrant, or pain referred to the back? Of the various theories proposed to explain the mechanism of referred visceral