Colonoscopy

Overview

A colonoscopy is a test that lets a doctor or nurse look at the inside of your large bowel (colon) and rectum. A thin, flexible tube with a tiny camera is passed into your back passage and gently guided around your bowel. It is used to check for problems such as polyps, inflammation, or cancer, and to take tissue samples or remove abnormal growths.

Yes, colonoscopy is a very common procedure. It is performed thousands of times every day around the world. Most people find it easier than they expected.

People of all ages may need a colonoscopy, but it is most often recommended for adults over 50, people with a family history of bowel cancer, or anyone with symptoms that suggest a problem in the bowel.

Symptoms

Common symptoms

• Bleeding from your back passage or blood mixed with your stools
• A lasting change in your normal bowel habits – such as looser stools, constipation, or needing to go more often
• Persistent abdominal (tummy) pain or discomfort
• Unexplained weight loss
• Feeling very tired or short of breath (which can be a sign of anaemia caused by hidden bleeding)

Symptoms in children

• Colonoscopy is much less common in children, but it may be needed if a child has persistent tummy pain, ongoing diarrhoea, blood in the stool, or poor growth.
• Children usually need to have the test at a specialist children’s centre, and they will be given extra support and sometimes a general anaesthetic.

Symptoms in older adults

• Older adults may notice the same symptoms as anyone else, but they should not ignore bleeding or changes in bowel habits – even if they come and go.
• Older adults are more likely to have bowel conditions, and a colonoscopy can often give clear answers.

Causes

Main causes

• To investigate symptoms such as blood in the stool, a change in bowel habit, or unexplained weight loss
• As a screening test for bowel cancer when a home stool test shows hidden blood
• To check for polyps, inflammation, or other changes in the lining of the bowel
• To take biopsies (tiny tissue samples) or remove polyps during the test

Risk factors

• A family history of bowel cancer or polyps
• Inflammatory bowel disease, such as Crohn’s disease or ulcerative colitis
• Getting older – most bowel problems are found in people over 50
• A previous finding of polyps or bowel cancer
• Lifestyle factors such as a low-fibre diet, high intake of processed meats, smoking, and heavy alcohol use

When to see a doctor

See a doctor urgently if:

• If you notice any bleeding from your back passage or blood in your stool
• If your bowel habit has changed for more than four weeks
• If you have unexplained weight loss, severe tummy pain, or low iron

Book a routine appointment if:

• If you are invited for bowel cancer screening and are unsure whether to attend
• If you have a family history of bowel cancer and want to discuss your options
• If you have symptoms that worry you, even if they come and go – a GP can reassure you or arrange tests

Diagnosis

A colonoscopy is performed by a specially trained doctor or nurse. It is usually done as an outpatient procedure at a hospital. Before the test, you will be given instructions to empty your bowels completely. During the test, you lie on your side and a thin, flexible tube with a camera is passed through your back passage and around your large bowel.

Tests that may be done

• A review of your symptoms, medical history, and physical examination
• A home stool test (called a FIT – faecal immunochemical test) that checks for hidden blood in your stool
• A flexible sigmoidoscopy – a similar test that looks only at the lower part of the bowel
• CT colonography – a special X-ray scan of the bowel if a full colonoscopy is not possible or appropriate

What to expect at your appointment

You will usually need to drink a strong laxative solution the day before to empty your bowels. On the day, you may be given a sedative to help you relax. You may feel pressure or cramping, but not severe pain. The test takes about 30–45 minutes. Afterwards, you rest for a short time and can usually go home the same day. If you had sedation, you will not be able to drive for 24 hours and will need someone to take you home.

Treatment

Colonoscopy is not usually a treatment by itself, but it allows your doctor to find and, in many cases, treat problems in the bowel during the same test. If a polyp is found, it can often be removed immediately. If a condition such as inflammation is seen, your doctor will discuss what to do next.

Self-care at home

• Follow the bowel preparation instructions from your hospital exactly – the test is only useful if your bowel is clear.
• Arrange transport home and have a responsible adult stay with you for the first 24 hours if you have sedation.
• Drink plenty of fluids after the test to rehydrate.
• Rest for the remainder of the day – do not drive, operate machinery, or make important decisions until the next day.
• If you have severe pain, heavy bleeding, or a fever after the test, contact your medical team immediately.

Medical treatments

If the doctor sees a polyp, they will usually remove it with a wire loop passed through the colonoscope. This is painless and does not require surgery. Biopsies (tiny tissue samples) can also be taken and examined under a microscope. If a condition such as inflammatory bowel disease is found, your healthcare team will explain the treatment options, which may include medication – but they will always tell you the exact medicines and doses.

When is surgery considered?

If a colonoscopy finds a cancer, or a large polyp that cannot be removed safely during the test, you will be referred to a specialist surgical team. Surgery usually involves removing the affected part of the bowel, and it is always planned carefully with you.

Living with this condition

After a colonoscopy, most people feel back to normal within a day or two. If you had a polyp removed, you may notice a small amount of blood from your back passage, which usually stops on its own. Your doctor will let you know when you can eat and drink normally and whether you need any further tests.

Lifestyle tips

• Eat a diet high in fibre – whole grains, fruits, vegetables, and beans.
• Drink plenty of water to keep your stools soft.
• Exercise regularly – at least 30 minutes a day, five days a week.
• Limit alcohol and avoid smoking to reduce your risk of bowel problems.
• Maintain a healthy weight.

Diet and exercise

A balanced diet with plenty of fibre and regular exercise helps keep your bowel healthy. After a colonoscopy, you can usually eat a light meal once you feel ready. Avoid heavy or spicy food for a day if your stomach feels unsettled.

Mental health and emotional wellbeing

Waiting for results after a colonoscopy can be stressful, and it is normal to feel anxious. Try to talk to someone you trust. If you are told you have a serious condition, you may feel shocked or low – these feelings are common, and support is available. Remember that having the test gives you clear information and is a positive step.

Prevention

Colonoscopy cannot prevent all bowel conditions, but it is one of the best ways to prevent bowel cancer. It allows doctors to find and remove polyps before they become cancer. A healthy lifestyle – including eating well, being active, staying a healthy weight, not smoking, and limiting alcohol – also lowers your risk.

Screening programmes

In many countries, bowel cancer screening is offered to people over a certain age. In the UK, the NHS Bowel Cancer Screening Programme sends home test kits to people aged 60–74, and this age range is gradually expanding. The test looks for hidden blood in your stools. If the result is abnormal, you will be offered a colonoscopy. Speak to your GP if you are due for screening or have a family history of bowel cancer.

Complications

If left untreated

• If a significant polyp is left alone, it may grow and turn into cancer over time.
• Symptoms like bleeding or a change in bowel habit could be a sign of a serious condition that will not improve without investigation.
• Bowel cancer is much more treatable when found early – a colonoscopy can save lives.

Long-term outlook

Colonoscopy is extremely safe and very successful at detecting problems early. Even when something is found, most treatments are effective, especially when started promptly. Most people who have a colonoscopy receive reassuring news. Complications from the test itself are rare, and your medical team will watch for them and treat them quickly.

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