Changes in how your bowel works

Treatment for rectal cancer can cause changes to the way the bowel works. These changes usually become less troublesome with time. But for some people, bowel changes continue for several months or more. This can take time to adjust to and there are ways to help manage the changes.

Bowel changes may include:

  • diarrhoea or loose stools
  • feeling the need to rush to the toilet (urgency)
  • leakage (faecal incontinence)
  • constipation
  • wind and bloating.

It’s important to tell your doctor if you have problems with your bowel. They can give you advice and do tests to find the cause. Some people may be referred to a bowel specialist (a gastroenterologist).

Treatment depends on the symptoms you have and what is causing them. Changes in diet, anti-diarrhoea drugs and exercises that strengthen the muscles used for bowel control may all help manage bowel problems.

Bowel changes

Most people have changes in how their bowel works following surgery and/or radiotherapy for rectal cancer.

Many people find that their bowel habits don’t go back to being exactly as they were before treatment. It may take at least a year for things to settle down. With time, bowel symptoms usually become less troublesome and most people find they get into a new routine that’s normal for them.

If bowel problems don’t settle, help is available. There are many things that can be done to improve bowel symptoms. Ask your doctor for advice. They can discuss with you what may help. They may also refer you to a specialist in bowel control problems for further assessment and treatment.


Changes in bowel function after surgery

If part of the rectum has been removed, there may be long-term changes to how your bowel works.

The rectum is the part of the large bowel that stores stool. It has nerves and muscles that help you to hold onto stools until you’re ready to pass them. After surgery these nerves and muscles may be weakened. This means that you can’t hold onto stools as well as before.

When stools pass through the bowel more quickly they may be softer and looser, or liquid. You may go to the toilet more often (frequency). Softer stools can be more difficult to pass out of the bowel completely. This can mean needing to go back to the toilet a few times after a bowel movement to finish passing the stool.

You may feel the need to rush to the toilet when the urge to pass a bowel movement comes on (urgency). There may be some leakage from your bowel or there may be occasions when you aren’t able to get to the toilet in time. This is called faecal incontinence.

You may also have less control over when you pass wind or find it difficult to tell the difference between wind and stool in the back passage.

During surgery to remove the rectum, the surgeon may make an internal pouch from a piece of bowel to act as a store instead of the rectum. If you have an internal pouch you may not have problems with urgency, but you may find it more difficult to empty your bowel completely and this can sometimes lead to constipation.

Some people alternate between having loose stools and constipation, or feeling bloated at times and having problems with wind.


Problems for people who have a stoma

If you had a stoma formed as part of your rectal surgery, it can take some time to adjust. You may have loose stools, or alternate between loose stools and episodes of constipation. You may also be more aware of wind produced by your bowel.

Some people find it difficult to predict when the stoma is going to be active.

Many of the suggestions for treating bowel function problems are equally relevant to people with a stoma.


Changes after radiotherapy

The blood supply to the bowel can be affected by radiotherapy, making the bowel tissue and the small blood vessels in it more fragile. This may cause bleeding from the back passage.

Radiotherapy can cause scarring (fibrosis) in the large bowel lining, making it thicker and less flexible. This causes solid waste to pass through more quickly than before, so nutrients may not be as well absorbed. The bowel will also be unable to hold as much solid waste (stool). The muscles that help to hold stool in the rectum can also be affected, which may cause problems with bowel control and leakage (incontinence).

Radiotherapy can also cause the bowel to narrow. If radiotherapy affects the small bowel, it may mean the bowel can’t cope as well with certain types of food such as dairy or wheat products. A few people develop conditions such as bile acid malabsorption or small bowel bacterial overgrowth.


Treating bowel function problems

There are a number of ways bowel problems can be treated. Which treatments are likely to work best for you will depend on your symptoms and what is causing them. It’s important that you see a doctor to be assessed.

Your cancer specialist and their team will probably have helpful suggestions. If your symptoms still don’t improve, you can ask your GP to refer you to a continence specialist or a specialist in stomach and bowel problems (gastroenterologist).

Treatments for bowel function problems are often based on one or more of the following:

  • changes in diet
  • anti-diarrhoea medicines
  • emptying the bowel more effectively
  • strengthening the muscles used for bowel control
  • retraining the bowel.

Back to Long-term and late effects

Managing bladder problems

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