Tests For Bowel Cancer: How Is Bowel Cancer Diagnosed?

Nearly 43,000 people are diagnosed with bowel cancer in the UK every year.

When diagnosed at the earliest stage (stage 1), around 90% of people will survive for five years or more. However, when diagnosed at the latest stage (stage 4), this drops significantly to just 10% of people.

If you have any symptoms of bowel cancer, such as blood in your stool, or are over 45 years old, it’s essential to get checked for bowel cancer as soon as you can — the earlier you receive a diagnosis, the better the chances of survival.

But how is bowel cancer diagnosed? Here, we take a look at the tests used to diagnose bowel cancer, what they involve, and when they might be done.

Tests for bowel cancer

There are a number of tests used to diagnose bowel cancer. The tests you may need to have will depend on the symptoms you’re experiencing, and if anything abnormal is found through initial testing.

If you go to see your GP, they will ask you a series of questions about your symptoms, as well as whether you have a family history of bowel cancer. They will also carry out an examination of your stomach and your back passage (rectum), known as a digital rectal exam (DRE).

If your symptoms suggest you may have bowel cancer or the diagnosis is uncertain, your doctor may suggest a few other tests.

Faecal immunochemical test (FIT)

A faecal immunochemical test (FIT) is a noninvasive test that looks for tiny amounts of blood in your poo.

This will likely be the first type of test recommended by your doctor if you have any symptoms of bowel cancer, such as changes in your bowel movements, abdominal pain or unexplained weight loss.

To do a FIT test, a sample of your stool is placed either in a tube or on a card, which is then sent to a laboratory for testing and analysis to look for blood in the stool. Blood can be a sign of polyps (growths in the bowel) or bowel cancer. While polyps are not cancer, they may turn into cancer over time. This type of test can usually be ordered online to do at home.

The NHS offers FIT home screening kits to help prevent bowel cancer or find it at an early stage when it's easier to treat. However, these are only available to people aged 60 to 74 years who are registered with a GP and live in England.

If you are younger than the bowel cancer screening age, you can order a home test kit online. Faecal immunochemical tests may be recommended for people aged 45 and older to check for the early signs of bowel cancer, or if you have a family history of bowel cancer or other risk factors linked to the disease.

If you’re over 45 and would like to get tested for bowel cancer, order Check4Cancer’s BowelCheck screening test today.

Flexible sigmoidoscopy

If your symptoms suggest you may have bowel cancer, your doctor will refer you to your local hospital for further testing.

Here you’ll have a simple examination called a flexible sigmoidoscopy. A flexible sigmoidoscopy uses a thin, flexible tube with a camera and light on the end (a sigmoidoscope) that is inserted into the rectum. This procedure allows your doctor to examine the lower part of the bowel.

In some cases, the doctor will insert small instruments through the scope in order to remove polyps or collect a small sample of tissue to send to the lab for analysis.

It might be recommended you have a flexible sigmoidoscopy if you’re experiencing abdominal pain, chronic diarrhoea, rectal bleeding or unexplained weight loss, as these are symptoms that can be caused by bowel cancer.


A colonoscopy is a type of procedure where a thin flexible tube with a small light and camera at the end is inserted into your back passage and moved along the bowel. This device is called a colonoscope — it’s like a sigmoidoscope but a bit longer, which allows the doctor to view the entire colon.

The procedure provides your doctor with images of the inside of your large bowel so they can identify any abnormal areas of tissue that could be caused by cancer.

While stool tests can be very effective in detecting bowel cancer, a colonoscopy is a more advanced test that allows doctors to take tissue samples (biopsies) and remove any polyps (growths) that can cause cancer.

You might have a colonoscopy to help find the cause of your symptoms and to look for signs of bowel cancer at an earlier stage than normal if you’re in a high-risk category.

CT colonography (or virtual colonoscopy)

A CT colonography, also known as a virtual colonoscopy, is less invasive than a normal colonoscopy. It uses a CT (computed tomography) scanner to create 3D images of the bowel.

A CT colonography is commonly recommended for people who can’t have a colonoscopy to help identify the cause of symptoms that may point towards cancer or another condition that requires treatment.

During the procedure, a radiographer will insert a thin, flexible tube into your rectum and pump gas or air inside. This inflates the bowel so that the CT scanner can produce clear images of the inside of your bowel.

During a traditional colonoscopy, your doctor is able to take biopsies and remove any polyps that may cause cancer but this is not possible with a virtual colonoscopy. If your provider identifies polyps during a virtual colonoscopy, you may need a follow-up traditional colonoscopy to remove them.

Bowel cancer home test kit

If you are over the age of 45 and worried about bowel cancer, you can order a bowel cancer home test kit today.

BowelCheck by Check4Cancer is a simple, reliable and accurate bowel cancer screening test that you can do in the comfort of your own home. This is a quantitative faecal immunochemical test (qFIT) that detects traces of blood in your faeces, which could be a sign of bowel cancer.

The test results will say whether the sample was abnormal or not, so you can seek further diagnostic testing and effective treatment as soon as possible if you need it.

Compared to the NHS England qFIT test, BowelCheck has a lower threshold for abnormal results — meaning it can identify more cancers.

How to test for bowel cancer at home

The BowelCheck kit contains everything you need to successfully take and return your test including a sample collection tube, protective sample case, sample label, return label, sample box and return envelope.

Following the instructions provided in your kit, collect your sample in the green tube at any time of day or night. Once you’ve collected your sample, simply pop it in the post using the labelling and packaging provided.

Once your sample has arrived at the lab, you can expect to receive your results within five days.

If your results come back as abnormal, we’ll call you before sending you your results letter to advise you on the best next steps. We’ll provide full clinical advice and support, and help you with a referral to a private consultant or to your NHS GP if needed.

It’s important to remember that abnormal results don’t always mean you have bowel cancer. It’s also possible that bowel cancer can be missed if no blood is detected during testing.

Bowel cancer is treatable and curable — especially if it is diagnosed early.

Screening is the best way to detect bowel cancer early on, increasing the chances of successful treatment and survival. Order your home kit today or speak to our friendly team for more information on 0800 085 6663.