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Pneumobilia is the presence of gas in the biliary system. Causes include a biliary-enteric anastomosis, an incompetent sphincter of Oddi and spontaneous biliary-enteric fistula. ==Pathogenesis== In a normal healthy individual with a normally functioning sphincter of Oddi there should be no air within the biliary tree. Pneumobilia is commonly seen after biliary instrumentation but can be seen due to other causes such as incompetent sphincter of Oddi, biliary enteric surgical anastomosis, spontaneous biliary enteric fistula (cholecystoduodenal ~70%), infection (emphysematous cholecystitis), bronchopleuralbiliary fistula (rare), and congenital anomalies. Anatomically common bile duct is located in proximity to the duodenum, crossing the first and second part of the duodenum posteriorly and further coursing down ending at the ampulla of Vater, where it is separated from the duodenum by pancreatic tissue. Nissen in his description of duodenal and peptic ulcer in 1945 claimed that this lateral separation isolates the common bile duct from complications of duodenal ulcer disease thus making choledochoduodenal an uncommon clinical entity. It is essential to distinguish between air in the biliary tree from air in the portal venous system in making a diagnosis of pneumobilia. Ulcerogenous choledochoduodenal fistula have been occasionally reported in the literature in the past and there have been very limited reports of such cases in recent years presumably due to better diagnostic and early therapeutic management of peptic ulcer disease. Biliary-enteric fistula was first described by Bartholin in 1654, but it was only in 1840 that Long established its etiological association with duodenal ulcer. Hunt and Herbst in 1915 first reported the radiographic diagnosis of spontaneous internal biliary fistula: that is, cholecystoduodenal fistula complicating cholelithiasis. Cholelithiasis is a common cause of these fistulas accounting for up to 90% of cases while ulcer disease accounts for only about 5 percent of biliary-enteric communications.〔ReMine WH. Biliary-enteric fistulas: natural history and management. Adv Surg 1973;7:69.〕 While cholelithiasis has been associated with cholecystoduodenal fistulas, peptic ulcer accounts for up to 80% of choledochoduodenal fistulas. Other rare causes that have been reported include duodenal diverticulum, paraduodenal abscess, operative trauma, and carcinoma of the duodenum, stomach and bile duct.〔Marshall SF, Polk RC. Spontaneous internal biliary fistula. Surg Clin North Am 1958; 38:679.〕〔ReMine WH. Biliary-enteric fistulas: natural history and management. Adv Surg 1973;7:69.〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「pneumobilia」の詳細全文を読む スポンサード リンク
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