Colon Sigmoidoscopy

You have been advised to have a flexible sigmoidoscopy examination. We will need to have your formal consent before we can carry out this examination. This information explains how the examination is carried out and what the risks are. This will help you to make an informed decision when agreeing to the examination. The consent form follows this information.


What is a flexible sigmoidoscopy?

This examination is a very accurate way of looking at the lining of the left side of your large bowel (colon). The instrument used is called a flexible sigmoidoscope or colonoscope. This is gently inserted into your rectum. The scope has a light which is shone onto the lining of your bowel. It also has a very small camera which sends a live image to a screen where it is viewed by the endoscopist.

During the examination your specialist may need to take some small tissue samples, called biopsies, for analysis under a microscope in the laboratory – this is painless. Images from the flexible sigmoidoscopy will be kept in your health record.

A sedative is not usually necessary. Rarely the doctor will recommend a sedative. Please see below for more information about this.

Why do I need a flexible sigmoidoscopy?

You have been advised to have a flexible sigmoidoscopy to help find the cause of your symptoms. The results will help us to decide on the best treatment for your problem and whether we need to carry out any further examinations. The reasons for this examination include:

  • bleeding from the back passage.
  • abdominal pain and diagnosing the extent of some inflammatory bowel disease.
  • follow-up inspection of previous disease.
  • assessing the clinical importance of abnormalities found on X-ray.

Polyp removal

Occasionally, the endoscopist might remove polyps during the flexible sigmoidoscopy. We may have already known about them or we may find them during the examination. A polyp is a protrusion from the lining of the bowel. Some polyps are attached to the bowel wall by a stalk look like a mushroom, whereas others are flat without a stalk. If a polyp is found it is usually removed by the endoscopist, as it may grow and cause problems later. Polyps are removed or destroyed using a high frequency electric current. Alternatively, the endoscopist may take some samples for further examination.

Are there any alternatives?

No. Rigid sigmoidoscopy does not reach the right area of the bowel and any other investigations do not allow us to collect tissue samples that may be important for diagnosis.

What are the risks?

A flexible sigmoidoscopy is a safe examination for the most people. Serious problems are rare, but life- threatening complications are possible. However, you need to weigh up the benefits against the risks of having the procedure. There can be risks from having the examination itself, as well as from the sedation.

The main risks are:

  • A tear (perforation) in the lining of the bowel. Nationally, this happens to approximately 1 in 15,000 people. The risk of a tear is higher with polyp removal. An operation may be required to repair the tear.
  • Risk of a missed lesion- although flexible sigmoidoscopy has been selected as the best test to diagnose your symptoms, no test is perfect. There is a small risk (1 in 100) that we might miss a large polyp or other important finding during your test.
  • Bleeding where we take a sample (biopsy) or have removed a polyp happens to about 1 in 150 people, but this is usually minor and stops on its own.
  • Short term problems with breathing, heart rate and blood pressure (related to sedation). We will monitor you carefully so that if any problems do occur they can be treated quickly. Older people and those with significant health problems (for example, people with serious breathing difficulties), may be at higher risk.
  • Heart attack or stroke (related to sedation) - though this is very unlikely.


Sedation is not usually required for this examination. If you find the procedure particularly uncomfortable, we may be able to give you Entonox (gas and air). This should work quickly to reduce the pain. After taking Entonox, you will need to rest in the department for 30-60 minutes until its effects have worn off. If you feel able to, you will be allowed to drive, as long as you have had no other sedation.

Rarely the endoscopist may recommend sedation. The sedative will be injected into a vein in your hand or arm and will make you lightly drowsy and relaxed, but will not put you to sleep. You will be aware of what’s going on around you and will be able to follow simple instructions during the examination. We will monitor your breathing and heart rate throughout the examination.

After sedation you will not be allowed to drive home. You should also not go home alone on public transport alone. You must arrange for a family member or friend to collect you. The nurse will need to be given their telephone number so that we can contact them when you are ready to go home.

If you have had sedation and live alone, we recommend that you try to arrange for someone to stay with you overnight.

For 24 hours after the sedation you must not:

  • Drive
  • Drink alcohol.
  • Operate heavy machinery
  • Sign any legally binding documents.

You are likely to feel back to normal after 24 hours.


Bowel preparation instructions

In order to be able to clearly see your bowel, it must be clean. When you arrive in the Endoscopy Unit you will usually be given an enema to make you go to toilet. You can eat and drink normally before you come to hospital.

Sometimes you will be sent an enema to self- administer at home. If you have been sent an enema please administer it to yourself at home one hour before your appointment. Please do not eat for 30 minutes before you use the enema or until after your sigmoidoscopy. You can drink water but no other liquids.

To use the enema, lie down on one side, remove the cap and then insert the full length of the nozzle into your back passage. Gently squeeze the tube until it is empty. Keep squeezing the tube as you pull the nozzle out of your back passage. This should not be painful; if you feel any resistance or pain, do not continue. Stay lying down on your side whilst you wait for the enema to work; this will usually take 2-5 minutes. Please refer to the enclosed leaflet for additional information about the enema.

What do I need to bring with me?

Please bring with you a dressing gown and a pair of slippers. Please leave all valuables at home. The hospital cannot accept responsibility for these items.

What about my medicines?

You should continue to take your routine medicines with the following exceptions:

  • If you are taking iron tablets you must stop these one week before your appointment.
  • If you are taking stool bulking agents (e.g. Fibogel, Regulan, Proctofibe), loperamide (Imodium), Lomotil or codeine phosphate, you must stop these 4 days before your appointment.


Please notify your specialist before your appointment if you are taking anticoagulants, e.g. warfarin, clopidogrel, dabigatran, rivaroxaban or apixaban.

What happens when I arrive at the Endoscopy Unit?

Soon after you arrive you will be reviewed by a nurse who will ask you a few questions about your medical condition and any past surgery or illness you have had. They will also check your heart rate, blood pressure, oxygen level and blood glucose. This is to confirm that you are fit enough to undergo the sigmoidoscopy examination.

We will give you an enema to make you go to the toilet (unless you have sent one to self-administer at home).

The nurse will also make sure you understand the examination and you will be able to ask any further questions or raise any concerns you may have. The nurse will ask you for signed consent form. If you have not already signed the consent form the doctor will be able to answer any questions you still have or talk to you about any concerns.

If the doctor has recommended a sedative (not usually necessary for this examination) the nurse will also ask you about your arrangements for getting home after your sigmoidoscopy as you must be accompanied home if you have had a sedative (see above).

What happens during the flexible sigmoidoscopy examination?

The nurse will ask you to remove your lower garments and put on a hospital gown. You will then be escorted into the examination room where the endoscopist and the nurses will introduce themselves and you will have the opportunity to ask any final questions. The nurse looking after you will then ask you any final questions. The nurse looking after you will then ask you to lie on the trolley on your left side.

First, the endoscopist will examine your back passage using their gloved finger and some gel before they gently inserting the sigmoidscope into your rectum and lower part of your bowel to examine the bowel lining. Air is gently passed into your bowel to make moving the scope around easier. You may feel some discomfort when the endoscopist moves the scope around the natural bends in your bowel. This is rarely uncomfortable enough to have to stop the procedure.

The examination takes 5-15 minutes to complete and you will be fully awake (unless your specialist has recommended you have a sedative. Please see the information above).

After the examination?

If you feel well, you can go home immediately after the examination. If you wish, you can rest in the recovery area for a short time. (If you have had a sedative or Entonox, please see above).

Before you leave the Unit, the nurse will explain what was seen during the examination and whether you need any further treatment or appointments. You will be able to go home or back to work straight afterwards.

How long will I be in the Endoscopy Unit?

You should expect to be in the Unit for approximately 2-3 hours. The Unit also deals with emergencies and these will take priority over people with outpatient appointments. However, we will try to keep any delays to an absolute minimum.

After you go home

  • Some windy discomfort is normal- this will settle after a few hours.
  • You may notice some blood next time you open your bowels. If a biopsy or polyp removal was carried out.
  • If you have any problems with persistent abdominal pain or bleeding during the next 48 hours after your sigmoidoscopy, please contact your specialist or the Manor Endoscopy Unit where you had your procedure performed.


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