Final answer:
The most common reason for ostomy surgery is inflammatory bowel disease, which includes Crohn's disease and ulcerative colitis.
Step-by-step explanation:
The most common reason for ostomy surgery is inflammatory bowel disease. Inflammatory bowel disease (IBD) is a collection of inflammatory conditions primarily affecting the intestines. It includes two main types: Crohn's disease and ulcerative colitis. Both of these conditions can result in complications that may necessitate the need for ostomy surgery.