A colonoscopy is a test that’s used to investigate the cause of your bowel symptoms. A thin tube with a small camera inside is passed into your bottom, so your doctor can have a look inside.

What is a colonoscopy?

A colonoscopy is a test that’s used to investigate the cause of your bowel symptoms. A thin tube with a small camera inside is passed into your bottom, so your doctor can have a look inside.

Your introduction to colonoscopy

Why you might need a colonoscopy

A colonoscopy is used to find out what’s causing your bowel symptoms, such as blood in your poo, long-term constipation or diarrhoea, pain, weight-loss or feeling tired all the time for no reason.

It can also help diagnose conditions such as irritable bowel syndrome (IBS), Ulcerative Colitis, Crohn’s disease, haemorrhoids, growths in your bowel (polyps) and bowel cancer.

Lots of people have polyps and most of the time they’re harmless. But they can sometimes become cancer, so if they’re found they need to be checked.

The good thing about a colonoscopy is that polyps can be removed during the procedure and tested. By removing polyps before they can become cancer, your cancer risk will be reduced.

Most of the time, we won’t find anything you need to worry about during a colonoscopy. However, a normal result will also help us rule out possible causes of your symptoms, bringing you one step closer to a diagnosis.

What happens during a colonoscopy?

A colonoscopy is usually done as an outpatient or day case. It normally takes around 30-45 minutes. We strongly recommend being sedated for the procedure, which will help you relax and feel more comfortable. This is usually given by an injection into a vein in your arm. The sedative will make you feel drowsy, but you’ll still be awake and aware of what’s happening.

We will ask you to lie on your side on a couch with your knees slightly bent. Your doctor will gently pass colonoscope into your bottom and then have a good look at your bowel. You’ll be able to see what your doctor sees, as the camera transmits the video onto a TV screen by the couch.

You doctor will then gently pump carbon dioxide gas inside. This opens up you bowel so that they can see the lining clearly. This can make you feel like you need the toilet, and cause some cramping and bloating. If you feel like you need to pass wind, don’t worry – this is completely normal. It’s best to let the wind out as otherwise it can be quite painful.

During your colonoscopy, some biopsies (small samples) of your bowel lining might be taken. This is painless. The samples will be sent to a lab for testing. If your doctor finds them, you may also have some polyps removed. These are small growths in your lining that could potentially turn into cancer. Removing these will reduce your cancer risk, which is a huge benefit.

How to prepare

Your doctor will let you know exactly how to prepare for your test. If you have diabetes, take blood thinners, have a pacemaker, or take certain medications, this can affect how you prepare, so make sure to talk to your doctor so you can prepare with confidence.

Generally, preparing for your test will look like this:

Seven days before
You will need to stop taking:

  • Iron supplements
  • Multivitamins
  • Pepto-Bismol
  • Charcoal tablets

These stain the bowel and make it harder to see.

You will also need to stop taking fibre supplements, although other laxatives are ok to keep taking.

If you take any gut medicines, or stronger pain killers – check with your doctor if you can keep taking these or whether you need to stop.

Two days before
You will need to start eating a low fibre diet. This will help make sure nothing is left over in your bowel once you’ve taken the bowel prep (a strong laxative).

If your bowel isn’t empty, the doctor won’t be able to see your bowel properly and may need to cancel your colonoscopy. This will mean you need to go through the bowel prep again, and if your procedure is being covered by insurance, you could get into difficulties, as they may refuse to cover the rescheduled procedure.

The day before
You will need to stop eating solid food 24 hours before your procedure and then take your bowel prep. The time of your last meal will depend on whether you have a morning or afternoon appointment.

Make sure you’ve checked your appointment and are completely sure when you should start fasting and when you can start drinking the bowel prep.

Once the bowel prep starts working, you should expect frequent bowel actions and eventually diarrhoea.
Some cramping is normal.

Our top tips

  • Use a barrier cream after each bowel action, to help reduce soreness.
  • Using wet wipes, rather than toilet tissue, will be gentler on your skin and help reduce soreness.
  • Bowel prep is designed to empty your bowels completely, and therefore it’s easy to get dehydrated. You can feel cold when you’re dehydrated, so drink plenty of fluids – at least ½ pint or one glass every hour (hot drinks will especially help) and keep a warm blanket with you.
  • You will find that you need to stay very close to the toilet for a few hours, so once the bowel prep starts working, keep a phone and a charger, or a book with you.

What happens after a colonoscopy?

Most people are ready to go home after resting for an hour or so. You may need to stay a bit longer for observation if you have had any polyps removed.

The sedative will normally make you feel quite pleasant and relaxed. However, you should not drive, operate machinery or drink alcohol for 24 hours after having the sedative. You will need somebody to take you home look after you for 24 hours until the effects have fully worn off. Most people can get back to normal the next day.

Your doctor will let you know the results straight away and what your next steps will be. You will be given a report to take home, as well as a copy which you can give to your GP. If you have had any polyps removed or a biopsy, the results should be ready in around one week.

To discuss your results and next steps, book a follow-up appointment with your doctor.

Contact us

To ask a question about a colonoscopy or to book an appointment, contact our specialist team available Monday to Friday 8am – 6pm or Saturday 9am – 1pm. 

Our GI team are caring and friendly and will find you the earliest appointment possible with the best specialist for your needs.

Call us on 020 7078 3802 or email us at [email protected]

prolapse treatment london

GI Clinic

The GI Unit is supported by a multidisciplinary team of medical and surgical consultants. Our expert team treats and supports patients with any gastrointestinal conditions.

A patient speaking to a receptionist

Patient information

Our Hospital is renowned for providing exemplary levels of care across more than 90 services. From orthopaedics, to urology, our private GP practice and Urgent Care Clinic, our services are led by some of London’s leading Consultants. For more information, and to find a service suitable for your care, find out more about the services that we offer.

Make an enquiry

If you have any questions relating to treatment options or pricing information, get in touch with us by filling out one of our contact boxes or giving us a call on 020 7078 3802.

Our Appointments Team have a dedicated and caring approach to finding you the earliest appointment possible with the best specialist.

If you are self-paying you don’t need a referral from your GP for a consultation. You can simply refer yourself* and book an appointment.

If you have health insurance (e.g. Bupa, Axa Health, Aviva), you will need to contact your insurer to get authorisation before any treatment, and in most cases you will also require a referral letter from your GP.

If you are not registered with a GP, we have an in-house private GP practice you can use. Alternatively, we can suggest the most appropriate course of action for you to take, given your location and individual circumstances.

*Please note – for investigations such as X-rays and MRIs, a referral will be required. However, we may be able to arrange this for you through our on-site private GP.

    Make an enquiry

    Latest articles

    The latest news, insights and views from St John and Elizabeth Hospital.

    Find out what we’re doing to keep you safe, read expert articles and interviews with our leading specialist Consultants, learn more about common conditions and get your questions answered.

    09th November 2023

    KFM and St John & St Elizabeth Hospital enter into partnership to deliver an end-to-end procurement and supply chain service

    On Wednesday 1 November 2023, KFM entered into a contract with St John…

    01st November 2023

    Men’s Health Awareness Month With Dr Adam Wander, Private GP

    November is Men’s Health Awareness Month, widely known as Movember. This is a…

    19th October 2023

    Kidney Stones – Prevention & Treatment with Mr Leye Ajayi

    Mr Leye Ajayi is a Consultant Urological Surgeon with a specialist interest in…

    03rd October 2023

    Preventing Rugby Injuries with Lead Outpatient Physiotherapist – Kolade Awobowale

    We are extremely proud that our Lead Outpatient Physiotherapist, Kolade Awobowale, flew out…

    Mr Akash Patel

    26th September 2023

    Top Tips for New Runners – with Mr Akash Patel

    Mr Akash Patel, Consultant Trauma and Orthopaedic Surgeon specialises in hip and knee…

    26th May 2023

    What to expect at our Stroke Clinic – with Dr Sageet Amlani

    It’s a tough reality that many of those who have had a stroke,…

    12th April 2023

    What does a Bowel Consultant do? Mr Asif Haq answers

    Mr Asif Haq is a highly experienced Colorectal Consultant and General Minimal Access…

    16th January 2023

    Skiing Q&A with an orthopaedic surgeon

    Mr Parag Jaiswal is a lower limb orthopaedic surgeon who specialises in complex…

    11th January 2023

    Shred it this ski season

    If you’re planning a holiday in the mountains this ski season, preparing your…

    10th January 2023

    Ski season and ACL injuries

    An interview with Mr Ghias Bhattee – Lower Limb Orthopaedic Surgeon on what…

    06th January 2023

    Getting treatment after a skiing injury

    Mr Satya Naique is a Lower limb Orthopaedic and Trauma Surgeon, who has…

    14th November 2022

    An insight into HoLEP – minimally invasive prostate surgery

    Mr Andrew Ballaro is a Consultant Urological Surgeon who practices at our hospital….