Spontaneous internal biliary fistula implys an abnormal communication between the biliary tract and other organs which is non-surgically formed most commonly by spontaneous passage of gall stones. It has been reported that the incidence of spontaneous biliary fistula is low and that cholecyst-duodenal fistula is the most common type of fistula. Author's experience, however, indicates that the actual incidence is not so low as previously considered and that choledochoduodenal fistula is far more frequently found than cholecyst-duodenal fistula. This report is concerned with clinical, radiological and endoscopic studies on 33 cases of spontaneous choledocho-duodenal and cholecyst-duodenal fistula which were found preoperatively by duodenofiberscopic examination in the past 5 years at the author's clinic. Followings are the conclusions obtained. 1) 33 cases of spontaneous internal biliary fistula was found among 246 cases of gall stone disease. The incidence (13 percent) is much higher than the figures indicate because the author's experience shows that not a few cases heal to close in a short period. In contrast to the previous report, choledocho-duodenal fistula (30 cases) was much more frequently found than cholecyst-duodenal fistula (3 cases). Author's experience suggests that many cases of choledocho-duodenal fistula have been overlooked without duodenofiberscopic examination. 2) Clinical evaluation revealed a characteristic attack of severe abdominal pain just like labor pain in 80 percent of cases. 3) Radiological evaluation revealed air shadow in the biliary tract in 36 percent of cases. The air shadow can be detected only by careful observation. 4) Choledocho-duodenal fistula was divided into three types, thpe Ⅰ, type Ⅱ and type Ⅲ, according to the site of fistula orifice. What type of fistula is formed depends on not only the size of stones but also the structual abnormality of the Vaterian bile duct. 5) The fistula either heals to close within 4 to 14 weeks or otherwise remains open with epithelization of the orifice. Final outcome of the fistula depends on the presence or absence of the obstructive lesions of the biliary tract distal to the fistula orifice.
As a result, most of Ⅰ type of choledocho-duodenal fistulae heals to close, most of Ⅲ type remain open and Ⅱ type takes either course half and half. 6) As for a clinical course, cases with residual gall stones in the biliary tract tend to have attcks of cholangitis as compared to those without stones. However, one third of cases without residual gall stones may have attacks at some time of clinical course. As a result, a surgical intervention is indicated to cases with residual gall stones. In cases without residual stones, however, an indication to the surgical intervention depends on the clincal course.