11553 Virtual Colonoscopy

Overview

A virtual colonoscopy — also called CT colonography — is a scan that lets doctors look at the inside of your large bowel (colon) without putting a camera inside you. Instead of a flexible tube with a camera, it uses a CT scanner: a large doughnut-shaped machine that takes many X-ray pictures from different angles. A computer then pieces these pictures together into detailed 2D and 3D images of your bowel lining. It is called 'virtual' because the journey through your bowel happens on a screen rather than with a camera.

Yes, it is fairly common. Many hospitals offer virtual colonoscopy as an alternative for people who cannot have, or would rather not have, a standard colonoscopy. The bowel problems it looks for are among the most common reasons people are sent for tests.

Mostly adults. It becomes more common with age because bowel polyps and bowel cancer are more likely as we get older. It can be used at any adult age when a doctor thinks it is the right test for you.

Symptoms

Common symptoms

• Often there are no symptoms at all — the test may be done as part of bowel screening or follow-up.
• Blood in your poo, or blood on the toilet paper
• A lasting change in bowel habit — looser poo, constipation, or going more or less often
• Tummy pain or cramping that keeps coming back
• Bloating or a feeling of fullness
• Losing weight without trying
• Feeling very tired or short of breath, which can be a sign of low iron (anaemia)
• A low iron level picked up on a routine blood test

Symptoms in children

• Virtual colonoscopy is rarely used in children. Children's bowel problems are usually looked at with different tests, and a specialist children's doctor (paediatrician) would decide what is needed.

Symptoms in older adults

• Most people who have this test are older adults, because bowel polyps and bowel cancer become more common with age.
• The test is usually well tolerated, but tell the clinic about other health conditions, kidney problems, or if lying still is uncomfortable for you.
• You may need extra time and a little help getting to and from the appointment.

Causes

Main causes

• Looking into symptoms such as blood in the poo or a change in bowel habit
• Checking for polyps or bowel cancer after an abnormal bowel screening result
• Following up people with a strong family history of bowel cancer
• Checking the bowel when a standard colonoscopy is not possible, or could not be completed
• Monitoring the bowel in some people with long-term bowel conditions such as inflammatory bowel disease

Risk factors

• Getting older — the chance of bowel polyps and bowel cancer rises from around age 50
• A close family history of bowel cancer or polyps
• A diet low in fibre and high in processed meat
• Smoking and drinking a lot of alcohol
• Being overweight
• Long-term inflammatory bowel disease, such as Crohn's disease or ulcerative colitis
• Type 2 diabetes
• Inherited conditions that raise the risk of bowel cancer

When to see a doctor

See a doctor urgently if:

• Blood in your poo, or bleeding from your bottom
• A change in bowel habit lasting three weeks or more
• Unexplained weight loss, or ongoing tiredness that does not improve
• A lump or swelling in your tummy
• Severe or worsening tummy pain

Book a routine appointment if:

• You have a strong family history of bowel cancer and want to talk about screening
• You have been invited for bowel screening and have questions about it
• You want to know whether a virtual colonoscopy or a standard colonoscopy is right for you
• You have ongoing bloating, wind or mild changes in your bowels that are bothering you

Diagnosis

This test is not a diagnosis in itself — it is one of the tools used to reach one. Your GP or specialist will first talk with you about your symptoms, health and family history, examine you, and may arrange blood or stool tests. A virtual colonoscopy is then booked if it is the best way to look at your bowel. A specialist doctor called a radiologist studies the images and sends a report to the doctor who referred you.

Tests that may be done

• A conversation about your symptoms, health and family history, plus a gentle tummy examination
• Blood tests, including a check for low iron (anaemia)
• A stool (poo) test to look for hidden blood
• Bowel preparation at home: a low-fibre diet the day before, then bowel-cleansing medicine so your bowel is empty
• The scan itself — you lie on a bed that slides into the scanner while a small tube in your bottom gently puffs air or gas into your bowel. You may be asked to hold your breath for a few seconds, and pictures are usually taken lying on your back and then on your front.
• Sometimes a standard colonoscopy afterwards, if something needs a closer look or needs removing

What to expect at your appointment

You usually arrive at the hospital or clinic about an hour before the scan, change into a gown, and have a short chat with the radiographer. The scan takes around 15 to 20 minutes. You may feel wind-like cramping or an urge to go to the toilet while your bowel is filled with air — this settles quickly once the air is let out. You can usually go home straight afterwards, but it is best to have someone travel with you. The scan uses a small amount of radiation, similar to what you get from everyday background sources over a few years; the benefit usually outweighs the risk, but tell the team if you are pregnant or could be. Results usually take one to two weeks — ask the clinic when to expect yours.

Treatment

The scan itself needs no recovery treatment. The 'treatment' part is what happens next. If your bowel looks clear, you may not need another test for several years. If small polyps are found, you will usually be offered a standard colonoscopy to remove them, often as a day case. If anything suspicious is seen, you will be referred to a specialist team who will explain the options and support you at each step.

Self-care at home

• Follow the bowel preparation instructions exactly — the test may need repeating if your bowel is not clean enough.
• Drink plenty of clear fluids while you take the bowel-cleansing medicine, and stay near a toilet.
• Arrange for someone to travel home with you, and keep the rest of the day gentle.
• Afterwards, sip water, eat light meals and move about gently to help trapped wind pass.
• Write down any questions and take them with you to your appointment.

Medical treatments

There are no medicines that treat the scan itself. If polyps are found, the usual next step is a standard colonoscopy so they can be removed during the same visit — removing polyps lowers the chance of bowel cancer developing later. If inflammation of the bowel is found, your specialist may suggest treatment for that condition. If cancer is found, you will be referred to a specialist team who will explain the treatment options in detail, which may include surgery, chemotherapy or radiotherapy depending on the stage and your general health. Your team will discuss what is right for you.

When is surgery considered?

Sometimes surgery is part of the plan. Polyps that are very large or in an awkward spot may need to be removed with an operation rather than through a colonoscopy. If bowel cancer is found, an operation to remove the affected section of bowel is often the main treatment. Your surgical team will explain what the operation involves, what recovery is like, and what support is available.

Living with this condition

Most people have a day or two of wind and bloating after the test, then get back to normal. The harder part is often the wait for results. It helps to plan something gentle for that week, keep normal routines going where you can, and share how you are feeling with someone you trust. If you are offered a follow-up test, ask what it involves so you know what to expect.

Lifestyle tips

• Eat more fibre — wholegrains, beans, pulses, fruit and vegetables
• Cut down on processed meat and red meat
• Keep active on most days
• Limit alcohol and do not smoke
• Aim for a healthy weight
• Drink enough fluids through the day

Diet and exercise

A balanced, fibre-rich diet and regular movement are good for your bowel in general. You do not need to be perfect — small, steady changes count. If your bowel is sensitive, a dietitian can help you find a plan that suits you, rather than cutting foods out on your own.

Mental health and emotional wellbeing

Waiting for results, or having a test that looks at your bottom, can stir up embarrassment, worry or fear — that is very common and completely understandable. Many people find the build-up harder than the test itself. Talk to your GP if anxiety or low mood is affecting your sleep, appetite or daily life; help is available and you do not have to cope alone. If you ever feel you cannot keep yourself safe, contact your local emergency number or a crisis support service in your area straight away.

Prevention

The test itself cannot be prevented — but the problems it looks for can often be prevented or found early. Bowel cancer usually starts as a small polyp, and removing polyps stops them turning into cancer. Eating well, staying active, not smoking and limiting alcohol all lower your risk.

Screening programmes

Bowel screening is offered in many countries, usually by testing a stool sample at home. In the UK, the NHS bowel screening programme invites people roughly from their early 50s up to age 74 — ask your GP about local arrangements. A virtual colonoscopy is sometimes used as an extra check if a screening test is positive, or if you cannot have a standard colonoscopy. Ask your doctor when your next screening is due; it is one of the best ways to catch bowel problems early.

Complications

If left untreated

• If polyps are left alone, some can slowly develop into bowel cancer over many years
• Bowel cancer found later is harder to treat than when it is found early
• Ongoing bleeding can lead to low iron (anaemia), causing tiredness and breathlessness
• Rarely, the test itself can cause a small tear in the bowel (perforation). This happens in a small number of people and is usually treated in hospital — tell the team straight away if you have severe pain, a hard swollen tummy, or a fever afterwards.

Long-term outlook

For most people the scan brings good news, or finds small polyps that are easily removed. Even when something is found, it is usually at an earlier, more treatable stage — which is exactly why the test is done. Whatever your result, there are clear next steps and a team to support you.

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