Colonoscopy and gastroscopy

This leaflet is for patients who are having a colonoscopy and a gastroscopy (OGD). This is an examination of your large bowel. This leaflet explains what it involves, and any significant risks that there may be.

Please contact the Endoscopy Unit if you cannot come to your appointment. If you do not let us know in advance, we may remove you from the waiting list.

Students and trainees supervised by qualified staff, may be involved in your care. If you do not want a student to be present, please tell the endoscopist or nurse-in-charge.

The time on your appointment letter is your booking-in time, not your procedure time. Please tell any friends or relatives coming with you to the hospital.

These tests take 40 to 50 minutes in total. It may take longer if you have biopsies or polyps removed. Most patients can go home immediately after their procedure. However, you will need to stay in hospital for about 45 to 60 minutes if you have:

• a sedative injection; and / or

• a polypectomy.

If there are emergencies or very complex cases, we may have to delay the start of your test. You may be in hospital for up to four hours.

How do I prepare for my test?

• For the test to be successful, your endoscopist must have a clear view of your bowel. Your bowel must be as empty as possible.

• It is important that you follow the advice we give you about how to prepare your bowel.

• As part of your preparation, we will give you a laxative. Please refer to the Instructions for MOVIPREP and PLENVU bowel preparation leaflet enclosed.

• If your bowel is not empty enough, we may have to cancel your procedure and repeat it on another day. This is due to the high possibility of the endoscopist missing important signs. Patients who have a bowel cancer diagnosed within two years of a previous examination, have probably had it missed at the time of their original examination. We call this Post Colonoscopy Colorectal Cancer Rate (PCCCR).

• You can drink clear fluids up to two hours before your appointment time. Do not drink milk.

• Important information for patients taking GLP-1 medication, such as Mounjaro, Wegovy, and Ozempic

  • Stop eating solid foods for 24 hours before your appointment. Drink clear fluids only (do not drink milk).

• If you are a diabetic or a haemophiliac, please phone the Endoscopy Unit for specific advice.

• If you have a pacemaker or ICD, please phone the Endoscopy Unit at least one week before your test.

• If you have been diagnosed with sleep apnoea and use a CPAP machine, please bring this with you to your appointment and tell the nurse on arrival.

• Please remove nail polish and all types of false nails before coming to hospital.

• Do not bring any valuables to the unit. East Kent Hospitals accepts no responsibility for loss or damage to personal property. Unless the patient has handed their property to Trust staff for safe-keeping.

• Please bring your dressing gown, slippers, and something to read during your stay. Patients feel a spare set of underwear is useful.

Can I continue to take my normal medications?

• If you take any of the following medication, phone the Endoscopy Unit at least one week before your test:

  • warfarin, clopidogrel, dabigatran, rivaroxaban, apixaban, edoxaban, or other blood thinning medications.

• Taking certain medications for your stomach, may affect your test results. Unless we have told you otherwise, please stop taking the following medicines seven days before your test.

  • Cimetidine (Tagamet)

  • Ranitidine (Zantac)

  • Nizatidine (Axid)

  • Lansoprazole (Zoton)

  • Omeprazole (Losec)

  • Pantoprazole (Protium)

  • Rabeprazole (Pariet)

  • Esomeprazole (Nexium)

  • Famotidine (Pepcid)

  Important: Do not stop these medicines if:

  • you have been diagnosed with an ulcer

  • you have Barrett's Oesophagus

  • you have been specifically advised by your doctor or specialist to continue taking them

  If you are unsure whether to stop your medication, please contact the Endoscopy Unit.

• You must stop taking the following drugs one week before your test:

  • iron tablets

  • stool bulking agents (such as Fybogel, Regulan, and Proctofibre).

• Continue to take other medications as normal, with a sip of water. Please bring a list of these with you to the Endoscopy Unit.

• If you have any queries about your medication, please ring the Endoscopy Unit. It is important to remember to bring any asthma inhalers or angina sprays with you.

Advice for patients taking GLP-1 medications, for example Mounjaro

GLP-1 medications include:

• Semaglutides, for example Wegovy, Ozempic, Rybelsus

• Tirzepatide (Mounjaro)

• Liraglutides

These medications are used to manage diabetes, cardiovascular disease, or weight loss. For patients who take these medications, food moves more slowly through their gut. As a result, if you take these medication you will need to stop eating earlier than other patients, to make sure your stomach is empty of food. 

• Do not eat food for 24 hours before your appointment. During this time, only drink clear fluids. Do not drink milk.

• If you take your GLP-1 medication daily, please take your last dose 24 hours before your procedure.

• If you take your GLP-1 medication weekly, please take your last dose one week before your procedure.

What happens when I arrive at the hospital?

• Please report to the Endoscopy Unit reception on arrival.

• A nurse will check your details, blood pressure, and pulse. If you are allergic to anything (medication, plasters, latex), please tell the nurse.

• We will ask you to remove any jewellery before your examination.

• Please tell the nurse if you have a pacemaker, replacement joints, pins, or plates.

• You will need to change into a hospital gown, your dressing gown, and slippers.

• If you have not had a laxative, we will give you an enema to clear your lower bowel completely.

• You will have the procedures explained to you during your admission. Please do not hesitate to ask any questions you may have. We will ask you to sign a consent form. Remember that you can withdraw your consent for treatment at any time.

• A nurse will stay with you throughout your examination.

Why do I need to sign a consent form?

All patients must give permission before they receive any type of medical treatment, test, or examination. Consent is usually given when you sign the consent form before your treatment, but we may ask you to give it verbally. 

• You must give your consent voluntarily.

• The hospital must give you all the information you need to make a decision about your treatment. This is so you can give us informed consent.  If you have not been given this information, or you have but you still have questions, please speak to a member of staff. 

• You must be capable of giving consent. This means that you understand the information given to you and can make an informed decision.

When we ask you to give consent, please use this time to ask any questions you may still have. For more information, please go to the NHS Consent for Treatment web page. Remember that you can withdraw your consent for treatment at any time.

What does the examination involve?

• We will insert a small needle into a vein in your hand / arm. If you have sedation, we will give you the sedative and / or painkiller before starting your examination. This will make you feel relaxed but rarely makes you fall asleep. The needle will be lightly strapped to your hand / arm until you recover from the procedure.

• For some patients we offer Entonox when they are having a bowel examination, or no medication at all. Entonox is the pain relief gas that women have while giving birth. It works by taking in a deep breath using a mouth piece.

• The nurse or endoscopist will discuss with you whether you will have a local anaesthetic (numbing) spray. We will spray this on the back of your throat. It has a bitter taste.

• The endoscopist or nurse will attach a small device to your finger, to record your pulse and breathing. If you have sedation we will give you oxygen.

• The nurse will place a cuff on your arm, this tracks your blood pressure if you have sedation. Please tell your nurse if there is a reason why we cannot use a certain arm.

• The endoscopist will place a small mouthpiece in your mouth.

• The endoscopist will gently insert the gastroscope into your stomach. This is not painful and will not make breathing or swallowing difficult. However, you may feel like retching and feel uncomfortable during your test.

• Your stomach will be gently inflated with air to expand it. This is so the endoscopist can see the lining clearly. The air is sucked out at the end of the test.

• The nurse may need to clear saliva from your mouth using a small suction tube.

• Afterwards the endoscopist removes the gastroscope easily, and the trolley is turned around.

• The endoscopist will perform a rectal examination before your colonoscopy.

• We will ask you to lie on your left side. Once you are comfortable, the endoscopist will gently insert the colonoscope into your back passage (rectum). The colonoscope is then passed around your large bowel (colon).

• The endoscopist may ask you to change positions during your procedure. They could ask you to lie on your back and / or right side, and in some cases on your tummy. This is to help them move the colonoscope round difficult bends in your colon.

• Air will be passed into your bowel to expand it. This allows the endoscopist to see your bowel lining more clearly. This may give you some discomfort (sometimes mild pain), but it will not last long.

• You may need to pass wind during your procedure, this is normal and the endoscopist is used to it. Please do not be embarrassed.

• The endoscopist may take a biopsy (a small sample of the lining of your bowel) during your examination. They will send this to the laboratory for more tests. You cannot feel this. The endoscopist may also take a video recording and / or photographs for your records.

• The endoscopist may remove polyps during your examination. You will not feel this either. Polyps are small growths in the lining of the bowel. They are not cancerous, but could turn into a cancer in years to come if we do not remove them.

  The endoscopist can remove the polyps during your colonoscopy by cutting them out. They do this by placing a small loop of wire through which a low current of electricity is passed, causing the stem to be burnt through.

• Afterwards the endoscopist removes the colonoscope easily.

Going home

• If you had sedation, you must have a friend or relative:

  • take you home; and

  • stay with you for at least 24 hours after your procedure.

• If you have had sedation, for 24 hours following your test you must not:

  • drive

  • drink alcohol

  • operate machinery, including the oven and kettle

  • sign important documents

• If you did not have sedation, the restrictions above do not apply.

• If you have had Entonox you cannot drive for 30 minutes after your last dose.

• You may notice that your bowels do not return to normal for a few days following your procedure.

• You may feel bloated due to the air we insert.

• You may have a mild sore throat, but this will pass and is nothing to worry about.

Are there any risks?

These tests are very safe, but there are some risks linked to these procedures.

• A reaction to the sedative. The sedative can affect your breathing, making it more slow and shallow.

• Damage to crowned teeth or dental bridgework.

• Fever (raised temperature).

• There is a slightly increased risk of developing a chest infection after a gastroscopy.

• When a biopsy is taken or a polyp is removed, there may be a little bleeding. This can happen to approximately one in every 100 to 200 examinations where a polyp has been removed. In most cases, the endoscopist can immediately stop any bleeding that occurs during the procedure. They do this by applying clips, using cautery (heat), or injecting medication.

  If the endoscopist cannot control the bleeding during the endoscopy, we may need to admit you to hospital for further treatment. This is very rare. Further treatment could include:

  • another endoscopic procedure

  • an angiographic (radiological) procedure to stop the bleeding

  • in exceptional cases, surgery.

• Please contact the Endoscopy Unit or go to your nearest Emergency Department immediately if bleeding:

  • continues after you have gone home

  • does not stop within 24 hours

  • is heavy

• A perforation is a little tear in the wall of the bowel. This is rare and can happen to approximately one in every 1000 colonoscopies.

  • During a gastroscopy the risk of making a perforation is less than one in 9,000.

  • The risk rises to one in 500 if we find a narrowing or a growth during the procedure.

  • If we do a balloon stretch to expand the narrowing, the risk rises to one in 50.

  We take every care to avoid perforation. If it happens you will need a short stay in hospital and more tests, such as a CT scan. You may need surgery to repair the hole and treatment with antibiotics.

Please talk to your endoscopist before your examination if you have any worries about these risks.

Are there alternatives to a colonoscopy?

Yes, there is a CT colonoscopy or a barium enema. These procedures need the same kind of bowel preparation as a colonoscopy. However they do not allow the endoscopist to remove polyps or take biopsies. So, if we find abnormalities during these procedures you would probably need a colonoscopy anyway.

Are there any alternatives to a gastroscopy?

Yes, you can have a barium swallow test, which allows us to get x-ray images of the same areas inside your body. But we get better pictures from a gastroscopy and can take biopsies at the same time. Both of which help with your diagnosis.

If we find an abnormality during the barium swallow, you would need a gastroscopy to examine or treat it.

Any further questions?

Please phone the Endoscopy Unit. The units are open Monday to Sunday 8am to 6pm.

• Endoscopy Unit, Kent and Canterbury Hospital, Canterbury
  Telephone: 01227 783058

• Endoscopy Unit, Queen Elizabeth the Queen Mother (QEQM) Hospital, Margate
  Telephone: 01843 234370

• Endoscopy Unit, William Harvey Hospital, Ashford
  Telephone: 01233 616274

If you have any questions between 6pm and 8am Monday to Sunday, contact the Emergency Department (ED).

• ED, Queen Elizabeth the Queen Mother (QEQM) Hospital, Margate
  Telephone: 01843 235030

• ED, William Harvey Hospital, Ashford
  Telephone: 01233 616207

Our units are regularly inspected and audited. Please ask if you want any information about our performance standards. You can also visit the Care Opinion web site.

A short film outlining what patients can expect when coming to hospital for an endoscopy is available on the East Kent Hospitals' YouTube channel.

[Web sites last accessed 20 October 2026]

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