The diagnosis is gallstone ileus, with a gall stone causing intestinal
obstruction. The gallstone has entered the bowel via a fistula from the
biliary tree, ie a bilio-enteric fistula.
The most likely diagnosis is gallstone ileus. A gall stone has eroded
its way into the intestine and has moved along to a part where its size
prevents it from progressing further. The narrowest part of the
intestine is the ileum about 2 feet proximal to the ileo-caecal
junction, this would correspond to the site where a Meckel's
diverticulum may be found.
There is very little else this clinical situation could be besides
gallstone ileus.
Metastatic cancer is a differential diagnosis, you can get obstruction
and the mass in the small bowel could be a tumour. However small
intestinal tumors are not common, and there would have to be a second
pathology to explain the gas in the biliary tree.
Adhesions are the commonest cause of obstruction seen. They usually
occur following previous surgery, again they don't cause gas in the
biliary tree.
Cholangio-carcinoma is a malignant tumor of the biliary tree that
presents as progressive jaundice and itch. It does not usually cause an
abnormal communication between the biliary tree and the bowel and will
cause obstruction late in the disease.
Gall stone ileus is a complication of large gallstones. A large stone
becomes impacted in the gallbladder, usually in Hartman's pouch and
there is a smouldering inflammation which culminates in the stone
eroding into the duodenum. It then passes along the intestine to the
point where the intestine is too narrow to accomodate the stone. The
patient typically gets an intermittent obstruction that presents more
like an ileus than an acute intestinal obstruction.
