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
[{'content': 'Saw tooth appearance in abdominal barium enema X-ray: \nSelect and explain. \nA. Multiple polyposis, B. Prediverticulosis, C. Ischemic colitis, D. Ulcerative colitis', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. (b) PrediverticulosisRef: Sabiston Textbook of Surgery, 20th edition, Pages 1330-32* Barium enema studies were primarily used before the advent of computed tomography (CT) scans and have largely been abandoned as a primary tool as they provide information only about the luminal surface of the colon and cannot be performed if perforation is suspected.* The findings include Saw-tooth appearance to the colon, usually sigmoid, with shortening of bowel, crowding of haustra and picket-fencing of folds is seen in prediverticular disease.', 'role': 'assistant'}]