Which procedure involves creating an external opening to the colon?

A colostomy is a surgical procedure that involves the creation of an external opening, or stoma, to the colon. This is typically performed when a part of the colon needs to be bypassed or removed due to conditions such as cancer, diverticulitis, or trauma. In this procedure, the end of the remaining colon is brought through the abdominal wall, allowing stool to exit the body into a colostomy bag.

Other procedures, such as colonoscopy and sigmoidoscopy, are diagnostic or therapeutic endoscopic examinations of the colon and rectum, involving the use of a camera to visualize the interior and not creating an external opening. Gastrectomy refers to the surgical removal of a portion or the entire stomach, which does not pertain to the colon either. Therefore, the colostomy specifically is the procedure that directly correlates with creating an external opening to the colon.