Changes in how your bowel works after bowel cancer surgery
Most people have changes in how their bowel works following surgery and/or radiotherapy for bowel cancer.
Most people have changes in how their bowel works following surgery and/or radiotherapy for bowel 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
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After bowel surgery your large bowel is shorter than before, so bowel motions pass through more quickly. This often settles as your body adjusts. But if part of the rectum has been removed, there may be long-term changes to how your bowel works.
Changes caused by a shorter bowel
You may find that stools pass through the bowel more quickly and are 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.
Stools may be stickier. You may need to wipe around your back passage more after passing a stool. This may cause sore skin.
Some people alternate between having loose stools and constipation, or feeling bloated at times and having problems with wind.
Additional changes after rectal surgery
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.
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.
Problems for people who have a stoma
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If you had a stoma formed as part of your bowel 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 to the bowel (pelvic radiotherapy)
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Pelvic radiotherapy can cause scarring (fibrosis) in the lining of the large bowel making it thicker and less flexible. This means that the bowel can’t hold as much and stools pass through more quickly than before. The nerves and muscles that help to hold stool in the rectum can also be affected.
These changes cause similar symptoms to those mentioned for bowel surgery. These symptoms include loose stools, more frequent bowel movements, feeling the need to rush to the toilet to move your bowels (urgency), and sometimes incontinence.
Bleeding from your back passage is also quite common. This can happen after pelvic radiotherapy because the small blood vessels in the lining of the bowel become more fragile. Usually the bleeding is mild and doesn’t need any treatment.
However, bleeding can be a sign of serious conditions (including cancer) so it’s important to get it checked if you notice persistent bleeding from your back passage. You should always tell your doctor if you notice bleeding from your bowel.
Possible changes to the small bowel after radiotherapy
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As well as its effects on the colon or rectum, pelvic radiotherapy can also sometimes affect the small bowel. This may cause one or more of the following conditions:
Sometimes after radiotherapy for rectal cancer the bowel can’t cope as well with certain types of food, such as:
lactose, which is found in dairy products
fructose - a sugar found in fruits (it may also be added to foods as a sweetener in products that are often labelled ‘no artificial sweeteners’)
gluten - a wheat protein found in breads, cakes, biscuits and pasta.
Eating certain foods may cause symptoms such as tummy cramps, feeling bloated and increased wind. If you think you have a food intolerance, ask your doctor to refer you to a gastroenterologist (stomach and bowel specialist).
Bile acid malabsorption
Bile acids help us to digest fats in our food. Pelvic radiotherapy may alter the balance of bile acids in the bowel. This can cause episodes of diarrhoea that come on suddenly.
We have more information about how bile acid malabsorption is treated.
Small bowel bacterial overgrowth
The large bowel contains lots of bacteria that help digest food. But, normally, there are almost no bacteria in the small bowel. After pelvic radiotherapy, bacteria may begin to grow in the small bowel. This is called small bowel bacterial overgrowth. It can cause a range of symptoms including: diarrhoea, stools that float, wind, bloating, constipation, feeling sick, vomiting and bad breath.
Small bowel bacterial overgrowth is treated with antibiotics.
You can read more about the possible late effects of radiotherapy to the bowel in our sections on pelvic radiotherapy in men - possible late effects and pelvic radiotherapy in women - possible late effects.