This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Small & Large Intestine, Subject name: Surgery
In a 27-year-old male, most common cause of a colovesical fistula would be: 
Select and explain. 
A. Crohn's disease, B. Ulcerative colitis, C. TB, D. Cancer colon
A: Crohn's disease
Answer: A: Crohn's disease 
Explanation: Ans. (a) Crohn's diseaseRef: Sabiston 19th edition, Pages 1247, 1313* Young male most common cause of colovesical fistula: CD* Old age most common cause of colovesical fistula: Diverticular disease* Overall most common cause is diverticulitis