Air in biliary tract is seen in all, Except:

Ans. is 'b' Sclerosing cholangitis (Ref. Sutton Radiology, 6/e, p. 957).First go through the causes of air in billary tract:Following surgery or endoscopic intervention on biliary tract.Gall stone fistulaMalignant fistulaPhysiological lax sphincterPerforation of peptic ulcer in biliary tract.Now let's see why option (b) is to be preferred.Option (a)Gall stone ileus is obvious to everyone.Option (c)Carcinoma gall bladder can cause air in biliary tract by forming malignant fistulae.Option (d)Endoscopic papillotomy- Any operation on biliary tract can cause air in biliary tract, moreover endoscopic papillotomy can lead to lax sphincter.