Surgery to remove part of your colon
BMJ Group Medical Reference
If you’ve having surgery for diverticulitis, your surgeon will cut out the damaged part of your colon and join the healthy parts back together. This is called colonic resection. 
You may need an emergency operation because of bad infection or blockage in your colon. This operation is sometimes done in two parts. This is because it may not be safe to rejoin your colon straight away. Instead, you’ll have the operation to join your colon back together a few months after the diseased part has been removed.
In the time between the two operations, the end of your colon will be connected to a temporary hole in your abdomen called a stoma. Your stools will go into a bag attached to the stoma. This is called having a colostomy.  Only about 1 in 6 people still get problems with diverticula after this type of operation. 
If you’re having a planned operation (a non-emergency operation) for diverticular disease, you may have laparoscopic surgery (also called keyhole surgery). This is when your surgeon makes very small cuts in your abdomen and uses a narrow tube with a camera to see your colon. To remove the diverticula, your surgeon will pass small operating tools through other small cuts in your abdomen. People who have this kind of surgery usually have less pain and recover more quickly than people who have surgery through a large cut in their abdomen.  One study found that people who had keyhole surgery were also less likely to have serious problems, such as bleeding, after their surgery.  However, we need more research to say which type of surgery is safer.
Your colon is the first 2 metres (6 feet) of your large intestine. During digestion, food travels from your stomach to your small intestine and then to your large intestine. What's not digested then leaves your body as a stool.
A colostomy provides a way for food waste to safely leave your body if your rectum has been removed or if your colon and rectum aren't working properly. Your surgeon creates a new opening for your colon (usually on your abdomen) so that your faeces can be collected in a bag called a colostomy bag.
A stoma is an opening created by a surgeon through part of a person's body. If you've had part of your bowel or rectum removed, you may have a stoma put temporarily or permanently in the skin of your abdomen so that you can get rid of waste material (faeces) from your intestines.
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