A colonoscopy is a procedure that allows a specialist to examine the inside of the large bowel (colon) using a thin, flexible tube with a camera and light at the end.
It is used to investigate symptoms such as changes in bowel habits, bleeding, or abdominal pain, and to help diagnose conditions such as inflammation, polyps, or bowel cancer.
During the procedure, small tissue samples (biopsies) may be taken, and polyps may be removed if needed.
Before your colonoscopy, you will need to take bowel preparation medication to empty your bowels, which is essential for clear views and an accurate, safe examination.
Preparing for your colonoscopy
Even if your GP has referred you for a colonoscopy, your first appointment will be with one of our pre-assessment Nurses. This initial assessment ensures that a colonoscopy is clinically appropriate and that you are safely prepared for the procedure.
We aim to offer timely access to care, and appointments are typically available promptly at a time convenient for you.
What to expect at your pre-assessment appointment
During this appointment, the pre-assessment Nurse will review your medical history in detail and discuss your current health. This will include:
- Any existing medical conditions
- Your current symptoms, including frequency and severity
- Previous investigations or treatments
- A review of your medications and any allergies
Basic observations such as blood pressure and pulse may be taken to ensure you are fit for the procedure. The nurse will explain the flexible sigmoidoscopy, including how it is performed, any potential risks, and answer any questions you may have.
Your healthcare team will also give you a detailed explanation of how to prepare for the procedure, including what to eat and drink in the days beforehand and any bowel preparation that needs to be done.
If needed, your case will be reviewed by a consultant gastroenterologist, who will oversee your care and confirm the plan for investigation.
Ongoing support
Following your pre-assessment, our team will provide clear instructions regarding bowel preparation and confirm your procedure date. We are committed to ensuring you feel informed and supported at every stage of your care.
Choosing the correct bowel preparation guidance
At the bottom of this page, you will find links to guidance on your bowel preparation.
It is important that you read and follow the link that matches the bowel preparation you have been prescribed, as advised by your pre-assessment nurse.
Some preparations may look similar but have different instructions. Please do not use a preparation that is not intended for you.
If you have any questions, please contact the endoscopy team on 0203 058 9083 or 0203 058 9068 for further clarification.
What happens during a colonoscopy
A colonoscopy usually takes between 30 and 45 minutes, although this may vary depending on individual circumstances.
At the start of the procedure, you will be asked to lie on your side. You will be offered intravenous sedation to help you relax and remain comfortable throughout. In some cases, pain relief medication may also be administered.
Your doctor will then gently insert a thin, flexible tube called a colonoscope into your back passage (rectum) and carefully guide it through the large bowel (colon). The colonoscope has a light and camera attached, which transmits images to a monitor, allowing the doctor to examine the lining of your bowel.
During the procedure, air or carbon dioxide will be introduced into the bowel to improve visibility. This may cause temporary bloating, cramping, or a sensation of needing to pass wind. These symptoms usually settle shortly after the procedure.
Biopsy or removal of tissue
If any abnormal areas or growths (such as polyps) are identified, the doctor may take small tissue samples (biopsies) or remove polyps using specialised instruments passed through the colonoscope. You will be informed if this is required. Tissue samples are sent to the laboratory for further analysis.
Colonoscopy to treat a condition
In some cases, a colonoscopy is performed not only for diagnosis but also to treat certain conditions, such as:
- Removal of polyps: Polyps can often be removed during the procedure to reduce the risk of bowel cancer.
- Treatment of bleeding: If bleeding is identified, it can be treated using clips, heat therapy, or injection therapy.
Recovery after a colonoscopy
A colonoscopy is usually performed as a day case procedure, meaning you can return home the same day. After the examination, you will rest in a recovery area until the effects of the sedation have worn off, If given. As sedation may cause drowsiness, you must arrange for a responsible adult to accompany you home. If required, we can assist in arranging a taxi.
For 24 hours following the procedure, you should not drive, consume alcohol, operate machinery, or sign important documents due to the residual effects of sedation.
It is common to experience mild abdominal discomfort, bloating, or cramping after the procedure. This is caused by the air introduced into the bowel and usually settles within a few hours. Passing wind can help relieve this discomfort.
If biopsies were taken or polyps removed, you may notice a small amount of blood in your stool. This is typically minor and short-lived. However, if you experience persistent bleeding, severe abdominal pain, fever, or feel unwell, you should seek medical advice promptly.
If any treatment was carried out during the procedure, you may be given specific aftercare or dietary instructions before discharge.
Most individuals recover quickly and are able to return to normal daily activities within one to two days.