When to consider a colonoscopy

Each year, around 700,000 Australians have a colonoscopy. But when is the procedure really needed?

By 2020, medical authorities expect one million colonoscopies to be performed in Australian hospitals.

But will they all be truly necessary?

Why have a colonoscopy?

The most common reason for a colonoscopy is to check for bowel cancer.

About 17,000 people – mostly over the age of 50 – are diagnosed each year.

When bowel cancer is found early, around 90 per cent of cases can be treated successfully, so early diagnosis is vital.

How to test for bowel cancer

The National Bowel Cancer Screening Program uses a faecal occult blood test, or “poo test”, to screen for bowel cancer.

The test is sent to Australians on their 50th birthday and detects minute traces of blood that may be a sign of early bowel cancer or a polyp – a tiny growth inside the bowel that could become cancerous.

If the poo test is positive for blood, people should be referred for a colonoscopy.

What is a colonoscopy?

The procedure is done under sedation and a long, thin instrument called a colonoscope is inserted into the anus and through the bowel.

It contains a camera so the specialist can check the lining of the bowel for polyps and remove these.

“The number of colonoscopies has risen faster than the rate of bowel cancer in recent years, which suggests we could be over-using this test,” says Melbourne gastroenterologist Dr Suzanne Mahady.

Dr Mahady says colonoscopies may be over-used to investigate irritable bowel syndrome and low iron levels in women, which is usually due to heavy periods and low iron in the diet.

“Other reasons include a fear of missing serious conditions, even if they are unlikely, or because people request to have a colonoscopy although symptoms don’t suggest it would be helpful,” she says.

The risks of a colonoscopy

There is around a one in 1000 risk of the bowel being perforated, which may lead to surgery or a colostomy bag. There is also a one in 1000 risk of major bleeding when polyps are removed.

“For older people, there is a greater possibility of heart or breathing complications or complications due to anaesthetic, so ask your doctor about your risk,” says Dr Mahady.

“A colonoscopy has risks that may not be justified if the likelihood of finding anything serious is very low. It’s important to discuss symptoms with your doctor.”

When is a colonoscopy necessary?

  • Look for blood when you go to the toilet – if this is new for you, a change in bowel habit such as new constipation, unexplained weight loss and stomach pain.
  • If your faecal occult blood test – poo test – is positive for blood.
  • If your mother, father, brother or sister had bowel cancer before the age of 55.

“If your parents developed bowel cancer after 70, it’s more likely to be age-related,” says Dr Mahady.

“Age alone is not a reason to have a colonoscopy. But if you are over 50 and have other symptoms, that’s a better reason to do it.”

This month is Decembeard, Bowel Cancer Australia’s campaign to raise awareness about bowel cancer.

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Written by Sarah Marinos.