A cholecystoduodenal fistula is a connection made between the gallbladder wall and duodenum due to pressure necrosis caused by chronic stones. This fistulous connection in some cases may lead to the passage of stones into the gastrointestinal tract which can cause obstruction, most commonly at the terminal ileum. These fistulas are most often diagnosed intra-operatively during cholecystectomy, but sometimes present as bowel obstruction (“gallstone ileus”). Other non-emergent symptoms include bile acid diarrhea. Patients with gallstone ileus will present with symptoms of obstruction (nausea, vomiting, lack of bowel function). Patients may also present with cholecystitis or cholangitis in an oral board scenario. The patient should be asked about the history of gallstone disease or symptoms, and the physical exam should include checking for surgical scars or hernias. In the case of gallstone ileus due to cholecystoduodenal fistula, take down of the fistula is not required, especially during the first procedure. It should be reserved for stable, healthy, young patients with minimal inflammation. Surgical management includes cholecystectomy, fistula takedown, and duodenal repair. Timing of surgical repair for the fistula depends on presentation and patient medical comorbidities.