Flexible sigmoidoscopy

Why do I need to have a flexible sigmoidoscopy?

You have been advised to undergo this investigation of the left side of your large bowel to help find the cause for your symptoms, thereby facilitating treatment, and if necessary to decide on further investigations. There are many reasons for this investigation including:

  • 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 or scan.
  • A CT Colonogram examination is an alternative investigation to flexible sigmoidoscopy. It has the disadvantage that samples of the bowel cannot be taken if an abnormality is found. If this is the case a subsequent endoscopic examination may be required.

What is a flexible sigmoidoscopy?

This test is a very accurate way of looking at the lining of the left side of your large bowel (colon). The instrument used in this investigation is called a flexible sigmoidoscope. Within each scope is an illumination channel which enables light to be directed onto the lining of your bowel, and another which relays images back on to a television screen. This enables the endoscopist to have a clear view and to check whether or not disease or inflammation is present.

During the investigation the endoscopist may need to take some samples (biopsies) from the lining of your colon for analysis. This is painless. These samples may be retained. A video recording and/or photographs can be taken for your records.


The left side of your bowel can be cleaned properly using an enema. This will be given by the nursing staff at the hospital on your arrival in the Endoscopy unit, or posted to you to be administered at home.

Please try and retain the fluid in your bowel for as long as possible (for about ten minutes) before going to the toilet.
You may eat and drink normally up until the time you have the enema, after that you may have only clear fluids until after the examination.

What about my medication?

Routine Medication

Your routine medication should be taken. If you are on iron tablets or stool bulking agents (eg Fybogel, Regulan, Proctofibe), loperamide (Imodium), lomotil, codeine phosphate etc; you must stop these three days prior to your appointment.


Please telephone the unit if you are taking warfarin, clopidogrel (Plavix), Rivaroxaban, Apixaban or Dabigatran.

How long will I be in the endoscopy department?

This largely depends upon whether you have sedation and also how busy the department is. You should expect to be in the department for the whole of the morning or afternoon depending on your appointment time. The department also looks after emergencies and those can take priority over the outpatient list. Please note that your appointment time is considerably earlier than your procedure time. This is to allow time for the booking in process.

What happens when I arrive?

When you arrive in the department, you will be met by a qualified nurse who will ask you a few questions, one of which concerns your arrangements for getting home. You will also be able to ask further questions about the investigation.
The nurse will ensure you understand the procedure and discuss any further concerns or questions you may have.

You will have a brief medical assessment when a qualified endoscopy nurse will ask you some questions regarding your medical condition and any surgery or illnesses you have had to confirm that you are fit to undergo the investigation.
Your blood pressure and heart rate will be recorded and if you are diabetic, your blood glucose level will also be recorded. Should you suffer from breathing problems a recording of your oxygen levels will be taken.

If you have not already done so, and you are happy to proceed, you will be asked to sign your consent form at this point.

The investigation

The nurse will ask you to remove your lower garments and put on a hospital gown. In turn you will be escorted into the procedure 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 ask you to lie on the trolley on your left side. They will then place the oxygen monitoring probe on your finger. The examination takes 10 to 20 minutes to complete and you will be fully awake.

You may experience discomfort within the left side of the abdomen but this is rarely distressing enough to stop the examination. You may be able to have gas and air (Entonox) to alleviate this.

During the procedure samples may be taken from the lining of your bowel for analysis in our laboratories. These will be retained. Any photography will be recorded in your notes.

Sedation/Gas and Air

Gas and Air is available for most patients to make the procedure more comfortable without the need for sedation.

If sedation is necessary it will be administered into a vein in your hand or arm which will make you slightly drowsy and relaxed but not unconscious. You will be in a state called co-operative sedation: this means that although drowsy, you will still hear what is said to you and therefore will be able to follow simple instructions during the investigation.

Sedation has an amnesic effect; this means you are unlikely to remember the procedure.

Gas and Air is available for some patients to make the procedure more comfortable without the need for sedation.

If you are sedated we will monitor your breathing and heart rate so changes will be noted and dealt with accordingly. For this reason you will be connected by a finger probe to a pulse oximeter which measures your oxygen levels and heart rate during the procedure. Your blood pressure may also be recorded.

Please note that if you do have sedation you are not permitted to drive, take alcohol, operate machinery or sign any legal documents for 24 hours following the procedure and you will need someone to accompany you home.

Risks of the procedure

Lower gastrointestinal endoscopy is classified as an invasive investigation and because of that it has the possibility of associated complications. These occur extremely infrequently; we would wish to draw your attention to them and so with this information you can make your decision.

The doctor who has requested the test will have considered this very carefully before recommending that you have it and as with every medical procedure, the risk must be compared to the benefit of having the procedure carried out.

The risks are small but can be associated with the procedure itself and with administration of the sedation.


Sedation can occasionally cause problems with breathing, heart rate and blood pressure. If any of these problems do occur, they are normally short lived. Careful monitoring by a fully trained endoscopy nurse ensures that any potential problems can be identified and treated rapidly.

The endoscopic procedure

The main risks are of mechanical damage:

  • Perforation (or tear of the bowel lining) – risk approximately 1 for every 15,000 examinations.
  • Bleeding may occur at the site of biopsy or polyp removal (risk approximately 1 for every 100 – 200 examinations where this is performed). Typically minor in degree, such bleeding may either simply stop on its own or if it does not, be controlled by cauterization or injection treatment.
  • Pain - usually this procedure is well tolerated. It is common to experience short lived discomfort, however, a small percentage of patients may experience pain with this procedure.

What is a polyp?

A polyp is a protrusion from the lining of the bowel into the lumen caused by an abnormal multiplication of cells. Some polyps are pedunculated (look like a mushroom) and are attached to the intestinal wall by a stalk and some are sessile polyps which attach directly onto the intestinal wall without a stalk. Polyps when found are generally removed or sampled by the endoscopist as they may grow and cause problems. A polyp may be removed in several ways which can include using electrical diathermy.

After the procedure

You will be allowed to rest in the recovery area, and if necessary observations made.

Before you leave the department, the nurse or doctor will explain the findings and any medication or further investigations required. They will also inform you if you require further appointments

If you have had sedation you will be allowed to rest for as long as necessary. Your blood pressure and heart rate will be recorded. Should you have underlying breathing difficulties or if your oxygen levels were low during the procedure, we will continue to monitor your breathing and can administer additional oxygen.

Once you have recovered from the initial effects of any sedation (which normally takes 30 minutes) you will be moved to a comfortable chair and offered a drink.

Any sedation is likely to affect your memory, so it is a good idea to have a member of your family or friend with you when you are given this information although there will be a short written report given to you (discharge letter).

If you have had sedation you may feel fully alert following the investigation, but however, the drug remains in your blood system for about 24 hours and you can intermittently feel drowsy with lapses of memory. If you live alone, try and arrange for someone to stay with you or if possible, arrange to stay with your family or a friend for at least 4 hours.

The nursing staff will telephone the person collecting you when you are ready for discharge.

General points to remember

  • If you are unable to keep your appointment please notify the endoscopy department as soon as possible.
  • It is our aim for you to be seen and investigated as soon as possible after your arrival. However, the department is very busy and your investigation may be delayed. If emergencies occur, these patients will obviously be given priority over the less urgent cases. The time on your appointment letter is your arrival time and not the time of your test, as some preparation is required before the procedure.
  • The hospital cannot accept any responsibility for the loss or damage to personal property during your time on these premises.
  • If you are having sedation, please arrange for someone to collect you.
  • If you have any problems with persistent abdominal pain or bleeding please leave a message on the Endoscopy help line for advice after the procedure. Contact details will be on the discharge letter.

This leaflet was adapted from work done by: Royal Hampshire Hospital, Winchester.

If you or the individual you are caring for need support reading this leaflet please ask a member of staff for advice.

How to contact us:

0117 414 5040

© North Bristol NHS Trust. This edition published January 2020. Review due January 2022. NBT002232

Flexible sigmoidoscopy