Patient Leaflets Team

  • Reference Number: HEY-953/2017
  • Departments: Endoscopy


This leaflet has been produced to give you general information about your procedure.  Most of your questions should have been answered by this leaflet.  It is not intended to replace the discussion between you and your doctor, but may act as a starting point for discussion.   If after reading it you have any concerns or require further explanation, please discuss this with a member of the healthcare team caring for you.


What is a Colonoscopy?

You will have seen your doctor with concerns about your bowels. Your doctor has arranged for you to be seen by a bowel specialist in a clinic. Your doctor and/or your specialist feel that a colonoscopy is the best way to investigate your bowel problems. In this way the whole of the large bowel is seen at one visit.


Colonoscopy is the examination of the large bowel using a long, flexible tube called a Colonoscope. The tube allows the colon to be viewed directly and for pictures of the lining and samples of the tissues to be taken. The benefits of this examination include the ability to take biopsies to analyse parts of the large bowel lining which may be abnormal. It also enables the removal of polyps without the need (in the vast majority of cases) for an operation.

What happens if I refuse the Colonoscopy?

It is your choice whether or not you have the procedure. This procedure can provide important information about your large bowel, help us to understand your symptoms and plan your treatment.

Please discuss this with the healthcare team looking after you.

What alternatives might be available?

Alternative examinations can be used to examine the large bowel. They are not suitable in all cases. These are:

Barium enema

This is an X-ray of the large bowel. A bowel preparation drink to clean out the bowel is taken the day before. It causes diarrhoea for a few hours. (This is also taken before a colonoscopy). This test almost always examines the whole of the large bowel but can miss small polyps especially in the left side of the bowel, or if diverticular disease is present. If polyps are found during this test, then a colonoscopy will need to be carried out later to find the polyp and remove it.

Flexible sigmoidoscopy

This is an examination very similar to a colonoscopy which uses a flexible tube to look at only the left side of the bowel. Its advantages include a much shorter procedure time – about 5 -10 minutes, patients do not need to be sedated and similarly biopsies can be taken and polyps removed.

However, only one side of the large bowel is seen and we have no information about the other side. Therefore a normal finding only refers to this side. If polyps are found, then depending on the size and type of polyp, a colonoscopy is needed to make sure there are no polyps on the right side of the bowel. This test is usually performed in combination with other tests, the most common being barium enema.

Combined flexible sigmoidoscopy and barium enema

This method is often used to investigate large bowel problems. The advantage is that the whole large bowel is seen, especially the left side. For people with worrying symptoms, these tests can be performed during one session for the sole purpose of ruling out serious disease, such as cancer. If these tests are performed on the same day, biopsies and polyps cannot be dealt with at the same time and a further visit to hospital will be required. With each of the above tests, the risk of serious complications is generally much smaller than for the colonoscopy.

What are polyps and why is their removal so important?

Polyps are benign growths, which arise from the lining of the large bowel. They are very common and can be found during colonoscopy. Generally, they do not produce symptoms. Their removal is important because some polyps, especially large ones, have the potential to change into bowel cancers. This can take up to ten years. We cannot tell just by looking, whether polyps contain cancer cells or not. They need to be removed and looked at under a microscope. Because of the risk of cancerous change in polyps, they are removed whenever they are found during the colonoscopy. If the polyps are large or if there is other disease present, the risk of bleeding and perforation are greater than a normal colonoscopy. Therefore, if the removal of polyps is unacceptable to you or you prefer to have them removed at a later date following further discussion with your doctor, please inform the endoscopist before you sign your consent and the examination begins.

Does a colonoscopy have any risks I should know about?

It is important to note that serious complications during colonoscopy are rare.

Complication rates vary across the United Kingdom. If you would like to know our rates for serious complications this can be discussed with you during your consultation. Complications can be described as minor (mild) or major (serious):

Minor complications:

These complications are common and expected but do not last for long and do not cause serious harm. They include;

  • feeling bloated after the examination
  • trapped wind
  • feeling faint and/or dizzy
  • cold sweats
  • feeling sick

We do keep a close eye on you in recovery and in the majority of patients these symptoms subside within15-20 minutes, or over a couple of days. Over this period bloatedness is common and may come or go. As long as you are passing wind and going to toilet, this will settle down. There is a small risk of bleeding from the rectum after colonoscopy. The entrance to your rectum, the anus, has a very good blood supply and so this is where piles are often found. The insertion of the camera can cause a little bleeding.  This should only be ‘spotting’ on the toilet paper or drops in the toilet bowl. It may take some days for this to subside.

Major complications:

These are complications, which can be serious and may lead to admission to hospital and sometimes an operation. On rare occasions these can be life threatening, especially in people with serious and/or unstable cardiovascular or lung problems. It is important to stress major and serious complications are rare. Complications, which can become serious and life threatening include:

  • Perforation of the bowel – A small tear may occur through the bowel wall. This can especially occur in a thin, diseased bowel or when polyps are being removed. If it occurs you may begin to feel unwell, feel nauseous or vomit; your tummy may become hard, swollen and painful. You may feel hot and shivery. These symptoms can occur within minutes of the perforation or may slowly develop over days.

If you have any of these symptoms please consult your GP or go to your nearest A&E department as soon as possible.

  • Bleeding – This can occur especially after the removal of polyps. Although great care is taken to ensure there is no sign of bleeding after a polyp is removed, the contraction of the bowel after colonoscopy (when getting rid of wind or when the bowels are next opened) can cause the area where the polyp was to bleed.

You should expect a little bleeding, such as ‘spotting’ on the toilet paper or small drops in the toilet bowl. This usually subsides quickly. If bleeding begins to increase and large clots of blood are seen and /or you begin to feel unwell or faint, please contact your doctor immediately for advice and help. Recent evidence puts the risk of perforation, sometimes accompanied by bleeding, at 1 in 1000. This can be higher with the removal of large, difficult polyps, especially in the caecum. This is usually the thinnest part of the large bowel.

  • Sedation – Some people, for reasons we still do not fully understand, are particularly sensitive to sedation. The breathing can be too shallow and too slow. In these cases we stop the examination, give more oxygen and if required we can give an antidote, which reverses the effect of the sedation. This is usually all that is needed and there are no lasting effects.

In some cases, when people have another serious illness e.g. heart disease, stroke, unstable angina, severe asthma or chronic bronchitis, the sedation drug can cause difficulty in breathing. This is rare and we do monitor breathing and heartbeat throughout the procedure and give you oxygen by nasal tubes.

If you have a known allergy or reaction to sedatives and anaesthetics, please let the endoscopist and your nurse know.

How do I prepare for the colonoscopy?

Please read the information leaflet.  Share the information it contains with your partner and family (if you wish) so that they can be of help and support.  There may be information they need to know, especially if they are taking care of you following this examination. Complete the health questionnaire sent/given to you as fully as possible. To be able to see the lining of the large bowel you will need to have your large bowel empty and free of faeces. To do this we will send you sachets of a special powder to mix with water and drink.  Instructions for how to take these sachets should have come with your appointment time. If not, contact the Endoscopy Department – (see contact numbers). It is very important that you follow the instructions carefully as failure to do so may mean that your test will be cancelled and another appointment made. This ‘bowel preparation’ will cause you to have diarrhoea. Sometimes it works within 1-2 hours but both sachets need to be taken to be effective. You must drink plenty of fluid during this time and avoid fizzy drinks. You will lose a lot of fluid and can easily become dehydrated making you feel unwell. Please also avoid red jelly as this can be seen during the test. If you have diabetes (especially taking insulin) or you have serious heart, lung or kidney problems, or are concerned that a health problem you have may be affected, then contact the Endoscopy Department at the hospital where you are having your examination (see contact numbers).

  • LATEX – Please inform the department if you have a confirmed latex allergy as this will affect your appointment time.
  • CJD (commonly known as mad cow disease) – Please inform the department if you have been notified that you are at risk of CJD/vCJD (Creutzfeldt-Jakob disease/variant Creutzfeldt-Jakob disease) for public health reasons.
  • PREGNANCY – It is important that you inform us if there is a possibility that you may be pregnant.  Any information you share with us will be kept strictly confidential.

Please contact the department if you have a pacemaker.

Due to the above or other individual reasons, we do admit some people to hospital for preparation and colonoscopy. Due to the nature of the examination we ask you to undress. A private changing area is provided. Although a gown and privacy shorts are provided, you may also wish to bring a dressing gown with you. With your appointment letter, a health questionnaire will be sent. Please complete this to the best of your ability. This forms an important part of assessing your ‘fitness’ for colonoscopy and the potential for complications to occur, so that action can be taken to eliminate or reduce these risks. If your health has deteriorated whilst waiting for this examination, please inform your Endoscopy Department. Your co-operation with the above is extremely important, without this your colonoscopy could be delayed.

Will I be able to eat before my colonoscopy?

Some foods such as plain chicken (not in a sauce), rice, clear soups and Bovril-like drinks may be taken – please refer to your Bowel Preparation information leaflet.

You should have nothing to eat or drink for 2-4 hours before your examination time, to ensure that your stomach is empty.  You will receive sedation which will make you sleepy and relaxed. Sometimes people feel sick and even vomit during this test.  By keeping your stomach empty there is less likely of any fluid entering your lungs should you vomit.

Where will I have my colonoscopy?

The colonoscopy will be performed in the Endoscopy Department. Specially trained endoscopists and nurses work here and are very experienced in the performance of colonoscopy and the care it involves. Your colonoscopy will be undertaken at Hull Royal Infirmary or Castle Hill Hospital depending on where your consultant is based.  Please make sure you go to the correct Endoscopy Department. Directions will be given with your appointment letter. All the staff will endeavour to make your stay as easy and dignified as possible. Please do not be afraid or embarrassed to ask questions.

Who will perform my colonoscopy?

A consultant, senior doctor or specialist nurse who is trained and experienced in performing the test may undertake this for you. Doctors and/or nurses who are undertaking endoscopy training may perform your procedure. An experienced endoscopist will supervise them. Your permission will be requested in advance for this. You may decline and the supervising endoscopist will perform the endoscopy.

Should I take my tablets during my bowel preparation and before coming for my Colonoscopy?

If you are taking tablets prescribed by your doctor or other specialist, you should continue to take these as normal. There are some medications that may need to be stopped or reduced for a period of time before your colonoscopy.  If you are taking any of the following medications, please contact your Endoscopy Department for further advice and instructions.

  • CLOPIDOGREL (PLAVIX) – Please inform the department if you are taking these tablets as these may need to be stopped prior to your procedure.
  • RIVAROXABAN, DABIGATRAN, APIXIBAN –  These are blood thinning medications and usually have to be stopped for a period of time to reduce the risk of bleeding.
  • WARFARIN –  These are blood-thinning tablets and may have to be stopped for a period of time before colonoscopy due to the risk of bleeding.
  • INSULIN AND/OR TABLETS FOR DIABETES – Insulin doses may have to be adjusted during the bowel cleansing period. Tablets for diabetes may have to be stopped. For some people with diabetes, we may need to admit them to hospital for the day and night before the test. There is a risk that the bowel preparation for the examination and restricted diet could make the control of your blood sugar difficult and make your diabetes unstable.
  • IRON – If you take iron tablets then these must be stopped for one week before the colonoscopy. Iron coats the inside of your large bowel making it very dark and difficult for the endoscopist to see anything. It is important to stop iron otherwise your colonoscopy will be cancelled and another appointment made.

If you have any concerns about whether to take your medications before your colonoscopy, contact your Endoscopy Department.

What happens to me in the Endoscopy unit?

  • On arrival you will be greeted by our reception staff. If you have not already done so you will be asked to complete a health questionnaire. Your nurse will be notified that you have arrived. If there are any delays you will be notified as soon as possible.
  • You will have a discussion with your nurse who will ask questions about your general health and medical history. Please feel free to ask questions. Your nurse will check your blood pressure, pulse and oxygen levels. Your nurse will also discuss pain relief options with you. This test is normally performed with sedation but you can choose not to have sedation if you wish. Sedation is medication that makes you sleepy but does not put you to sleep. You will not be able to drive or operate machinery for 24 hours after the sedation is given to you. Your nurse will explain this to you in more detail.  As an alternative to sedation you may wish to consider using Entonox® for pain relief. Entonox® is a well-established pain relieving gas mixture. It consists of two gases, 50% nitrous oxide and 50% oxygen. You may already know that Entonox® is used to relieve pain during childbirth. It is also used widely by the ambulance service and in hospitals for a variety of procedures and conditions. 
  • You will need to remove your lower clothing and will be given a gown and privacy shorts to change into. A place to do this will be provided, ensuring your privacy. If you have a dressing gown please bring this with you.
  • If you are having sedation a ‘cannula’ is inserted into a vein in your hand or arm. This requires a needle to be inserted into a vein which is then removed leaving a very small plastic tube through which your sedation will be given. This will be removed you have recovered from the sedation.
  • We want to involve you in decisions about your care and treatment. Your endoscopist will discuss the examination with you and will answer any questions you have. You will then be asked to read and sign a consent form. If you need glasses to read, please keep them with you at all times do not leave them with a relative or tucked away in a bag or pocket.

How will I feel during and after the Colonoscopy?

You will be taken through into the examination room and asked to lie on your left side on the examination trolley. Your belongings will be put in a plastic bag and will be with you all the time. Once in position, your nurse will attach a finger probe, which monitors your oxygen levels and pulse throughout and after the examination. If you are having sedation we will give you a little oxygen via nasal tubes. If you are having Entonox your nurse will advise you how to do this. The endoscopist will examine your bottom with a finger. This allows lubricating jelly to be applied and to examine the first few centimetres of the large bowel, which is sometimes not seen by the camera. When the camera is inserted into your bottom, air is gently passed into the bowel. This opens up the bowel so the endoscopist can see where he/she is going.  At first you may feel that you want to go to the toilet. You may feel a little anxious and embarrassed that you will pass a motion. DO NOT WORRY. The first part of the large bowel begins to stretch. This sends messages to your brain telling you to go to the toilet. It is the air that causes this feeling. You will not mess yourself. As the camera is gently inserted further into the large bowel, this feeling should ease, but may not totally go away. The large bowel is not straight. It has twists and turns. Sometimes this makes it difficult to steer the camera around these bends. In these cases more air is used and sometimes a bit more pressure to the end of the camera to help push and pull the camera around the bend. This can cause discomfort and varies from person to person. It may be an ache and you may feel bloated, especially under the ribs. Instinct tells you to hold your breath until it passes. Try to relax and control your breathing, with good gentle, slow deep breaths. Your nurse looking after you will support you. Sometimes it can be quite painful. You must let your nurse and the endoscopist know. We can stop and remove some air. The colonoscopy will take approximately 20-30 minutes.

What happens when the colonoscopy is finished?

You will be asked to stay on your side whist the trolley is moved into the recovery room.  A nurse will continue to monitor your recovery; this will involve checking your blood pressure, pulse and oxygen levels at regular intervals. Gradually, as you recover, you will be advised to get rid of any ‘wind’ that may be trapped in your large bowel. We do appreciate that this can be embarrassing but it is important you do ‘let it go’. You will eventually be able to sit up and when your nurse feels it is safe you will be able to get off the trolley and get dressed. Please take care if you have had sedation as initially you may feel dizzy and a little disorientated. You will then rest in a chair you where you will be offered a drink and a biscuit.

Do I really need someone with me after colonoscopy?

This depends on the type of pain relief you have. Entonox works only when you breathe it in. Its effects wear off very quickly once you have stopped using it, normally within a minute. After a rest period in the recovery area and a drink and a biscuit you may drive home and do not need someone with you afterwards. If you have sedation, you must have someone to escort you home and stay with you for 24 hours. He/she should come with you for the appointment or be contactable by phone when you are ready to leave. If you do not have an escort or have not arranged for someone to collect you, then your procedure will be cancelled. If you are unable to arrange someone to collect you, please contact us to discuss alternative arrangements.

The sedation lasts longer than you may think, so in the first 24 hours after your examination, you should not:

  • Drive or ride a bicycle
  • Operate machinery or do anything requiring skill or judgement
  • Drink alcohol
  • Take sleeping tablets
  • Go to work
  • Make any important decisions, sign contracts or legal documents.
  • Be left alone to care for children.

You should rest at home following your procedure, you can eat and drink normally.

Will I be told what was found and what happens next before I leave the Endoscopy unit?

Yes. Your nurse and the endoscopist will explain the results to you. If you have sedation you may forget what has been said. This is why it is important to have someone with you. The information will be written down and further supporting information in the form of leaflets will be given if required.

Will I ever need a colonoscopy again?

This will depend on the reason for colonoscopy, what is found and whether it was possible to complete the colonoscopy examination. Colonoscopy can be used for bowel screening. Some people have a family history or genetic predisposition to developing bowel polyps and/or cancers. Some may have had bowel cancers already removed. In this case regular checking of the bowel with colonoscopy is needed. If polyps are found, they are removed. Depending on the type and size of the polyp, the bowel may need to be checked at regular intervals to ensure the polyp has been completely removed and no new ones have grown. For some, despite following instructions and taking the bowel preparation to empty the bowel, the view with the camera is poor. The endoscopist cannot be certain that the entire large bowel has been seen. In these circumstances, a repeat colonoscopy is needed and an alternative bowel preparation may be prescribed. Occasionally, people’s bowels have very severe twists and turns and it becomes too difficult for the endoscopist to get the camera all the way round. Sometimes, despite sedation, it is too painful for the patient and he/she asks the endoscopist to stop. In these cases a barium enema x-ray is needed to examine the rest of the large bowel. If you do need a repeat colonoscopy, do not worry. It is not because something serious has been found but usually for the reasons described above.

 Further information

If you require further information about your test your GP, consultant, and the Endoscopy Department is a valuable source of information.

  • A Guide for Adults. (Available from the Endoscopy Department)
  • A Guide for Relatives and Carers. (Available from the Endoscopy Department)

These are free of charge.

Useful contact numbers:

The Endoscopy Department, Castle Hill Hospital – Telephone number:  (01482) 622069 Mon – Fri:  8am – 5pm

The Endoscopy Department, Hull Royal Infirmary – Telephone number: (01482) 674790 Mon – Fri:  8am – 5pm

Ward 100 Hull Royal Infirmary – Out of hours  telephone number (01482) 675100

What do those words in the leaflet mean?

Biopsy – A sample of tissue is taken for analysis.

Caecum – The first part of the large bowel; this is joined to the small bowel.

Consent – This is the agreement between you and the endoscopist.  You are agreeing to have investigations or treatment and that you understand the purpose, benefits, alternatives and risks. You and the endoscopist during this process usually sign a consent form.

Colonoscopy – The examination of the inside of the large bowel using a long, flexible camera.

Endoscopy Department – The place where your procedure takes place

Endoscopist – This can either be your consultant, an experienced and trained doctor or an experienced and specially trained practitioner.

Perforation – A rare, but possible risk in which a hole or tear is made through the large bowel.

Polyp – A common, benign (not cancer) growth arising from the lining of the large bowel. They take some years to develop. Some polyps, depending on their size and type, have the potential to turn cancerous.

Polypectomy – The removal of a polyp usually performed at the same time as the colonoscopy.

This leaflet has been written with the help, support, advice and collaboration of:

  • Consultants in the Academic Surgical Department and the Department of Colorectal Surgery
  • Consultants of the Department of Gastroenterology
  • Staff of the Endoscopy Departments at Castle Hill Hospital and Hull Royal Infirmary

The patients and carers who have shared their experiences of colonoscopy with me and helped in auditing the information produced for readability, understanding and user-friendliness.

The patient pictures are reproduced with the permission of Health Press Limited from Neild P, Gazzard B. Patient Pictures – Gastroenterology, Oxford Health Press, 1997.



This leaflet contains important information about having a colonoscopy.  It provides information to enable you to make decisions about whether you are in agreement with the planned colonoscopyIt is extremely important that you have read this leaflet.

In particular it provides information about the purpose and intended benefits, side effects and risks of having a colonoscopy.  It also explains consent to undergo the procedure and where further information can be found and from whom.

 Sources of further information and contacts are given at the end of this leaflet.



I have read the Colonoscopy leaflet.  Yes No
I understand the information it contains.  Yes No
I understand the purpose of the colonoscopy, intended benefits and alternative tests  Yes No
I accept that that there are potential risks of colonoscopy which include bleeding and perforation (puncture, tear, hole) of the bowel and I have been given every opportunity to discuss this with my consultant and/or person performing the colonoscopy.  Yes No
I understand and accept that biopsies (samples of tissue) may be taken.  Yes No
I understand and accept that polyps will be removed if deemed necessary by the endoscopist, due to the reasons explained in this leaflet.  Yes No
I feel I have had the opportunity to seek further information, ask questions and have received information and answers to my satisfaction.  Yes No

Patient Name ……………………………………………………………………………..

Signature ………………………………………………………………………………….

Date ………………………………………………………………………………………..



General Advice and Consent

Most of your questions should have been answered by this leaflet, but remember that this is only a starting point for discussion with the healthcare team.

Consent to treatment

Before any doctor, nurse or therapist examines or treats you, they must seek your consent or permission. In order to make a decision, you need to have information from health professionals about the treatment or investigation which is being offered to you. You should always ask them more questions if you do not understand or if you want more information.

The information you receive should be about your condition, the alternatives available to you, and whether it carries risks as well as the benefits. What is important is that your consent is genuine or valid. That means:

  • you must be able to give your consent
  • you must be given enough information to enable you to make a decision
  • you must be acting under your own free will and not under the strong influence of another person

Information about you

We collect and use your information to provide you with care and treatment. As part of your care, information about you will be shared between members of a healthcare team, some of whom you may not meet. Your information may also be used to help train staff, to check the quality of our care, to manage and plan the health service, and to help with research. Wherever possible we use anonymous data.

We may pass on relevant information to other health organisations that provide you with care. All information is treated as strictly confidential and is not given to anyone who does not need it. If you have any concerns please ask your doctor, or the person caring for you.

Under the General Data Protection Regulation and the Data Protection Act 2018 we are responsible for maintaining the confidentiality of any information we hold about you. For further information visit the following page: Confidential Information about You.

If you or your carer needs information about your health and wellbeing and about your care and treatment in a different format, such as large print, braille or audio, due to disability, impairment or sensory loss, please advise a member of staff and this can be arranged.

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