If your GP thinks you may have a bowel problem, they will refer you to hospital. You will get an appointment for an outpatient clinic where the specialist may decide you need one or more of the following tests:
- Endoscopy (usually flexible sigmoidoscopy or colonoscopy)
- Virtual colonoscopy (CT colonography)
There may be a number of reasons why you have been referred for further investigations. You may have gone to your GP with symptoms, or had an ‘abnormal’ result via the screening programme, or you may have a family history of bowel cancer. Whatever the reason, the specialist will choose from the range of investigations detailed below and explain why the test chosen is best for you and any possible risks.
An endoscopy is a test which uses a small thin tube with a camera to look inside the body. There are lots of different types of endoscopy, but usually you will have either a flexible sigmoidoscopy or a colonoscopy to look inside your bowel.
Flexible sigmoidoscopy looks inside the rectum (back passage) and the lower part of the large bowel (sigmoid colon). This is where the majority of polyps (non-cancerous growths) and bowel cancers start. During this procedure, if the doctor or nurse sees anything that needs further investigation, samples (biopsies) can be taken for examination in the laboratory.
In some areas of England, the NHS bowel cancer screening programme invites people aged 55 for a one-off flexible sigmoidoscopy. As part of the screening programme the test is referred to as ‘bowel scope’.
Read more about bowel cancer screening.
A colonoscopy is an examination to look at the lining of your whole large bowel, to see if there are polyps or a cancer within any part of it. A long flexible tube with a bright light and a tiny camera on the end is inserted through your back passage and enables the doctor or nurse to get a clear view of the bowel lining. During the test, if the doctor sees anything that needs further investigation, photographs and samples (biopsies) can be taken. Simple polyps can be removed during a colonoscopy.
Preparing for a sigmoidoscopy or colonoscopy
The most important part of preparation is bowel cleaning. When the bowel is cleaned out properly, there is a better chance of seeing the bowel wall clearly to spot any changes.
Before having a sigmoidoscopy you will need to have some kind of bowel preparation, to make sure the doctor or nurse can see the bowel lining clearly. The bowel preparation for a sigmoidoscopy is usually an enema (medicine given straight into the back passage) on the day of the test.
Before having a colonoscopy you may be seen by a specialist nurse or screening practitioner, have a telephone call or be sent instructions in the post. You should be asked about any medical conditions to make sure it’s safe for you to have both the preparation and the test. Bowel preparation usually involves a combination of medicine to drink and a temporary change in your diet.
You will be sent bowel preparation instructions with your appointment letter. Contact your endoscopy unit if you have any questions about this.
Making you comfortable
If you are anxious about the procedure, talk to the doctor or nurse about your concerns and ask whether you can have sedation. If you have problems lying flat, or being able to curl up on your side to have the test done, let the nurse know straight away so that alternative arrangements can be made if necessary.
After a colonoscopy, the gas that was used to inflate the bowel can sometimes cause discomfort in your abdomen or shoulders for a short time. Peppermint chewing gum or warm peppermint tea, massaging your abdomen or walking about can help to relieve this and help the gas pass out of your body.
Virtual colonoscopy (also known as CT colonography) involves using a CT scanner to produce two and three dimensional images of the large bowel and rectum. This can be used for patients who are not suitable for regular colonoscopy due to other medical reasons.
It is sensitive enough to detect shape changes such as polyps within the bowel. However, it can’t easily detect flat areas of inflammation or change in the lining of the bowel, take samples or remove polyps in the same way as flexible sigmoidoscopy or colonoscopy, so you may still need to have this too.
During the procedure, gas is used to inflate the bowel via a thin flexible tube placed in your back passage. CT scans are then performed with you lying on your back, and then on your front, to enable the doctors to get a clear set of scans of your bowel. You will be asked to hold your breath for approximately 20 seconds in both positions.
Virtual colonoscopies are not currently available in every hospital.
Waiting for test results
Ask the doctor or specialist nurse when you can expect to find out the results and whether it will be via a clinic appointment, a phone call, or a letter. If you do have bowel cancer, your doctor and specialist nurse will talk to you about what happens next.
If your test results show that you do not have bowel cancer, you will either be referred back to your GP, or if other tests or treatments are needed for a problem unrelated to cancer, these can be arranged by the hospital doctor or via your GP.
Updated August 2018. Due for review August 2021.