The colon, or large intestine, may need to be removed for various reasons, including colon cancer, diverticulitis, inflammatory bowel disease, etc. In fact, the entire colon and rectum can be removed if medically necessary. In most cases, however, only a segment of colon needs to be removed to remove the disease, and the colon can then be reconnected. The majority of patients will then go on to have normal bowel movements. If a more substantial segment of colon needs to be removed, then bowel movements may be more frequent and stools looser in caliber.
Prior to a planned colon surgery, a bowel prep will be necessary to clean out the colon and reduce the bacterial count in the colon, to allow for a safer surgery. When the colon is reconnected, it is done so using a surgical stapling device. These staples will remain in your body, but they will not trigger any metal detectors. They are quite small and become incorporated into your tissue over time, so you will never know that the staples are in place.
When emergency surgery is performed on the colon, then a colostomy is routinely performed. Because the bowel has not been cleaned out prior to the emergent procedure, it is very unsafe to reconnect the colon. The likelihood of the reconnection (or anastomosis) breaking down and leaking is quite high, which would necessitate a second emergency surgery. In order to provide the safest possible outcome, a colostomy is performed. In most cases, the colostomy is temporary, and can be reversed with a second surgical procedure several months later. The colostomy may be permanent if it was performed for a low-lying rectal cancer and the anal sphincter was removed, or if an elective surgery to reverse the colostomy is considered unsafe for the patient with significant medical problems.
The two most common indications for colon surgery are colon cancer and diverticular disease. Colon cancers are usually diagnosed during colonoscopy, a procedure performed under intravenous sedation in which a camera is inserted into the rectum and the entire colon is visualized. If a mass or polyp is found, a biopsy is taken. Polyps can be benign or premalignant, and simply removing the polyp can sometimes be curative. When colon cancer is found, a colon resection becomes necessary. When the colon is removed for colon cancer, the lymph nodes that drain that segment of colon are also removed. The lymph nodes are then examined by the pathologist to determine if the cancer has spread. If there has been spread to the lymph nodes, then chemotherapy is recommended after surgery.
As mentioned above, a colostomy is sometimes necessary when colon surgery is performed. A colostomy is an opening on the skin through which the colon has been connected. Rather than having bowel movements through the rectum, the colon empties into a bag that has been placed over the opening on the abdomen. The rectum is stapled off from the inside, so nothing except occasional mucous or residual stool will pass from the bottom until the rectal stump is empty. Reversing the colostomy involves a second operation, in which the two ends of colon are once again reconnected, and the continuity of the colon is restored. Typically, this operation can be performed after a few months of recovery.