This information is meant only for patients of the London Gastroenterology Centre who are having a flexible sigmoidoscopy test done. If this does not apply to you, please leave this page.

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Flexible Sigmoidoscopy Information Leaflet

You can also click on each section below to find the specific information you need. 

Please ensure that your insurance company authorises the test BEFORE you arrive at the hospital. Please contact us and advise us of the pre-authorisation code. The code for Flexible Sigmoidoscopy is H2502. For further information please contact us.

A flexible sigmoidoscopy is a test to examine the inner lining of the last part of your large bowel or colon. Unlike a full colonoscopy, which examines the entire large
bowel, this test only examines the rectum and sigmoid colon (the left side of the colon). In the examination room you will be made comfortable on a couch, lying on your side. A nurse will stay with you throughout the test. The test is usually done without sedation as it is quick and not particularly uncomfortable. If you want, you can ask the doctor to give you a sedative injection to make you sleepy and relaxed. The doctor will gently insert a flexible tube with a camera on the end (called a sigmoidoscope) through your anus (back passage) into your large bowel. The bowel will be gently inflated by passing air through it to give a clearer view of the bowel lining and the doctor will check whether any disease is present. When the test is finished, the sigmoidoscope is removed quickly and easily. The test takes  approximately 10 minutes. You will, however, be in the hospital for a total of 2-3 hours.

Please click on the relevant section headings to find out what you need to know. 

Blood Thinning Medicines

If you are taking clopidogrel (Plavix) for a coronary artery stent, you must only stop this after discussion with the doctor. Other patients taking clopidogrel should usually stop this 7 days before the procedure. If you are unsure whether you should stop this you must ask us.

We usually ask patients to stop taking warfarin for 7 days before the procedure also. If you have had a heart valve replacement, you must not stop your warfarin but you must let us know. You may require a special drug regime before the test.

If you are taking one of the new blood thinning agents such as apixaban, rivaroxaban, dagibatran etc, you will usually need to stop these 2 days before the procedure. Please check with us.

Other Regular Medicines 

You should continue to take your other medicines normally but follow any specific advice you have been given with regard to your regular medications. We may ask you to stop taking diuretics and non – steroidal anti – inflamatory drugs and sometimes we may ask you to stop taking acid suppression medicines such as omeprazole and other PPI drugs.

Morning procedure:

Blood pressure medicines should be taken no later than 2 hours before the test is due with a small amount of water.

For all medicines you have not stopped, except for blood pressure medicines, please take these only AFTER the test.

Afternoon / evening procedure:

For medicines you have not stopped, please take the morning dose normally. Please take lunchtime or evening doses only AFTER the test.

If you have any questions, please ask us. 

Please follow the correct section below.

For patients taking insulin:

 For a procedure taking place in the morning:

 On the evening before, take your normal insulin dose.

On the morning of the procedure, take your normal dose after the procedure is finished.

For a procedure taking place in the afternoon or evening:

 On the morning before the procedure, take half the normal dose of insulin.

Take your normal dose of insulin when you eat after the procedure is finished.

For patients taking tablets:

 For a procedure taking place in the morning:

 On the evening before, take your normal tablets.

On the morning of the procedure, take your normal tablets after the procedure is finished.

For a procedure taking place in the afternoon or evening:

 On the morning before the procedure, take half the normal dose of tablets.

Take your normal dose of tablets when you eat after the procedure is finished

You are not allowed to eat for 6 hours but you can drink fluids until 4 hours before your procedure. Please continue to take all medication as normal including the day of the procedures unless you have been advised otherwise.

Please go to the endoscopy unit. You will be shown to your cubicle where you will meet the nurse who will look after you during your stay. She will also verify your personal details and preferred method of payment.

The nurse will then prepare you for your procedures. If you have any worries or questions at this stage don’t be afraid to ask. The staff will want you to be as relaxed and informed as possible for the test and will be happy to answer your queries.

The procedure will happen about 45 minutes after you arrive.

 Your doctor will explain the test to you and will ask you to sign a consent form. This is to signify that you understand the test  and its implications. Please tell the consultant or nurse if you have had any allergies or bad reactions to drugs or other tests.

About the test

When you go into the endoscopy room you will be asked to remove any false teeth and lie on your left side on a trolley. You will have some equipment attached to you so we can monitor you blood pressure and your oxygen levels.  

Some people prefer to be sedated (sleepy) for the tests although most people do not need it for this test. If you have sedation, the doctor will administer the medication via a small plastic tube placed in the back of your hand or arm.  The medication may take a few minutes to work. The medication makes you relaxed and drowsy; it is not a general anaesthetic. The doctor will then start the procedure by gently passing the sigmoidoscope through your back passage (anus) and into the large bowel (colon). The flexible sigmoidoscopy usually takes around 10 minutes.

Sometimes the doctor takes a biopsy (a sample of the bowel lining). A small piece of tissue is removed painlessly through the scope, using tiny forceps. This is then sent to the laboratory for further tests.

Does it hurt?

It should not be painful but you may experience a windy sensation in your tummy and a fullness as if you need to go to pass wind or go to the toilet. This is quite normal, even though the bowel is empty. If this happens, allow yourself to pass any wind.

Immediately After The Test

After the test, you will return to your cubicle. If you do not have sedation you will be free to leave within half an hour after the procedure.

If you have been given sedation, you will stay there for approximately one hour so the effects of the sedation can wear off. Your blood pressure and oxygen levels will be monitored during this time. You will also be offered a drink and some biscuits. You may bring your own food if you prefer.

One of the doctors or nurses will come to explain the results of your procedure. You should expect to stay in the hospital for a total of 2-3 hours.

After Sedation

If you have had sedation, do not use public transport, particularly if you will need to stand on the train or bus.

DO NOT drive yourself. Please have someone to take you home in a car or taxi.

DO NOT drink alcohol, drive a car or operate heavy machinery for 24 hours after sedation is given.

When You Get Home

Once you get home you may eat and drink as normal. You may find that you have a sore throat. You may also feel a bit full up or bloated. This is because of the air in your bowel. This feeling usually only lasts for a few hours but may last for a few days in some people. Peppermint or chamomile tea helps release the trapped wind and buscopan or mebeverine tablets can reduce any cramps you feel. These tablets can be bought at any chemist.

What are the Risks?

Procedure Risks

Gastroscopy is a common test with very few side effects or complications. However you should be aware of the following potential complications:

Overall, the risks of haemorrhage (bleeding) or perforation (a hole in the lining of the bowel) are very low at about 1 in 15,000 (British Society of Gastroenterology). If treatment is carried out, the risks are higher but are still low. The doctor will give you specific information about the risks in your case. Sedation causes breathing problems in about 1 in 200 cases although these are usually mild (British Society of Gastroenterology). You will be monitored through out the procedure and the sedation can be reversed if necessary. Other rare problems include aspiration pneumonia and a slight risk to teeth or dental bridgework. Sometimes the doctor is unable to complete the entire test. It is possible to miss abnormalities during the test.

Other Potential Side Effects

If you have any allergic reactions including rash, itchy, redness and swelling please contact the endoscopy unit or the emergency services if you feel very unwell or short of breath. 

What are the Alternatives?

Barium Swallow or Barium Meal: These are X-ray tests. They are not as accurate as gastroscopy for most conditions although for a small number of people with swallowing problems, a barium swallow can be useful. 

Abdominal Ultrasound: This test is useful for detecting gallstones and abnormalities in the liver and kidneys. It cannot easily examine the stomach, however.

Manometry and pH studies: These tests are sometimes very helpful for patients with swallowing difficulties and may be used in addition to gastroscopy.

Abdominal CT scan: This test can examine the entire abdomen. It involves X-rays, however, and no biopsy samples, so it is generally used as a follow up test, for example to determine the size of a growth seen during gastroscopy.

Sometimes due to emergencies and other unforeseen circumstances your appointment may be delayed. We try our best to see everyone on time but please understand that delays can occur and we ask for your patience in these circumstances.

Given that delays can occur, it would be a good idea if you bring a book with you to read while you are waiting or bring some relaxing music to listen to. Reading a good novel will get you into a calm state of mind as will the right music. Both will help make the procedure more pleasant for you. 

The hospital aims to ensure that your procedure is as safe as possible. Staff are swabbed regularly. Patients with Covid-19 are treated in separate areas to those who do not have the disease. If you have Covid-19 you must cancel your procedure and have it done after you have recovered. 

To ensure safety for all patients and staff, we follow these rules:

If you are double vaccinated you will need to do a lateral flow test the day before the procedure. You should upload the result to the NHS app and bring a copy of the certificate to the hospital showing that you are Covid negative.

If you are not at least double vaccinated, please follow strict self-isolation for a minimum of 3 days prior to your procedure. Please also follow increased vigilance – social distancing, washing hands regularly, wearing a face covering in public places, limiting contact with other people, 7 days prior to your procedure. You will need to have a negative PCR swab performed within 3 days of the procedure. We can arrange this for you. 

Getting to and from the hospital

To minimise the risk of catching Covid-19, particularly when case numbers are high, please avoid public transport. If someone is bringing you to the hospital, they will usually need to stay away from the hospital itself. They should collect you at the entrance when you are ready to leave.