This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: G.I.T, Subject name: Surgery
Which one of the following is the treatment of gall stone ileus 
Select and explain. 
A. Cholecystectomy alone, B. Removal of obstruction, C. Cholecystectomy , closure of fistula and removal of stone by enterotomy, D. Cholecystectomy with closure of fistula
B: Removal of obstruction
Answer: B: Removal of obstruction 
Explanation: Classically, there is impaction about 60 cm proximal to the ileocaecal valve. The patient may have recurrent attacks as the obstruction is frequently incomplete or relapsing as a result of a ball-valve effect. A radiograph will show evidence of small bowel obstruction with a diagnostic air-fluid level in the biliary tree. The stone may not be visible. At laparotomy it may be possible to crush the stone within the bowel lumen, after milking it proximally. If not, the intestine is opened and the gallstone removed. If the gallstone is faceted, a careful check for other enteric stones should be made. Ref: Bailey & Love&;s Sho Practice of Surgery,E25,Page-1190