Having a Flexible Sigmoidoscopy

A sigmoidoscopy is a routine test to examine the lining of your sigmoid colon. This is the lower part of your colon, also called your bowel or large intestine.

The examination uses an endoscope, which is a flexible tube about the thickness of your little finger, with a camera and light at one end. It is passed through your anus (back passage) and carefully moved around your large bowel by a specially trained doctor or nurse, called an endoscopist. Sometimes biopsies (small tissue samples) of your bowel may be taken for analysis.

During the investigation, your bowel will be gently expanded with carbon dioxide gas or water. Because your bowel is not straight, this stretching of the bowel during procedure may cause a little discomfort.

The procedure usually takes 10-15 minutes, although you may be in the hospital for about two hours.

Unfortunately, due to the nature of the investigations and individual needs of each patient, it is not always possible to run to time. The staff will try to keep you informed of any delays.

Why do I need a flexible sigmoidoscopy?

This procedure will allow your doctor or nurse to be able to get a clear view of the lining of your colon. This will help your doctor or nurse to diagnose your symptoms or check any bowel condition that you have had diagnosed in the past. Polyps (small growths in the bowel) can also be removed during the examination.

How safe is a flexible sigmoidoscopy?

Serious complications are extremely rare (one patient in every 10,000). The most serious risk is the endoscope damaging your colon during the test. This can cause an infection, bleeding or a perforation (tear) of the lining of the bowel. If this happens, your abdomen may become painful and bloated, and you may need medicine or surgery to treat the problem.

As with all tests this procedure will not always show up all abnormalities and on very rare occasions, a significant abnormality may not be identified. This can be due to the folds in the bowel, the way the bowel is situated or due to faecal residue remaining in the bowel.

If a biopsy is taken or a polyp is removed during the test, you may pass a small amount of blood from your anus after the test. This should only happen up to 12–24 hours after the test and is usually no more than a few teaspoons full.

Please note that occasionally the test may need to be abandoned or may be incomplete. This can happen if you find the procedure too uncomfortable or if the bowel preparation did not empty your bowel completely. In this case, the test may need to be repeated, or we may suggest an alternative procedure. Your doctor or specialist nurse will discuss these potential risks with you in more detail. Please ask questions if you are uncertain.

Is there an alternative to a flexible sigmoidoscopy?

Yes. An X-ray examination or CT colonography scan may show the cause of your symptoms, however, these tests are generally considered to be less accurate than a flexible sigmoidoscopy and involve radiation. Alternatively, a colonoscopy may be arranged which is a camera test that looks at the whole of your large bowel.

If you are unsure about this examination, please seek more information from your referring doctor.

Preparing for your flexible sigmoidoscopy

You do not need to take a day off work until the day of the examination.

The rectum and the lower colon must be completely emptied of faeces for the procedure to be performed. You will need to start a light diet two days before your procedure and take medication that has been prescribed. (NB: please follow the instructions attached and not those of the manufacturer).

You should have had a chance to discuss any medications you are taking with one of our nurses or doctors before your procedure. If you are taking anti-platelet medication or anticoagulant medication to prevent the formation of blood clots (such as aspirin or clopidogrel, warfarin, rivaroxaban or dabigatran); sedatives, chronic pain medication, or medications for diabetes, please let the doctor or nurse know in good time before the date of your procedure.

You should continue to take all your medications as normal, unless you have been told otherwise by the doctor or endoscopy nurse.

Planning your care 

If you are taking any of the following medications or have the medical conditions listed below, please contact the Clinical Advice Line on 01305 253152 to help us plan appropriate care and management of your condition during your visit with us: 

Please continue all other medications as usual.

Instructions for bowel preparation prior to your flexible sigmoidoscopy

There are three types of bowel preparation for this procedure, full liquid preparation, tablets or an enema; you will be advised when your appointment is booked which preparation you will need to take. If you are having an enema on arrival, there are no special preparations for the test. If you are having bisacodyl or full preparation, please see attached instructions for diet and the bowel preparation.

Please bring with you:

• A list of your medications, inhalers and GTN spray if required
• A dressing gown and slippers for your dignity and comfort and a bag to put your clothes in after changing for your procedure
• Your consent form.

What happens when you get to the Endoscopy Unit

When you come to the Endoscopy Unit, please give your name to the receptionist. A nurse will take you to a private office. You will be asked some questions about your health. The nurse will check your breathing, pulse and blood pressure. If you take Warfarin, your INR may be checked and if you are diabetic, your blood sugars will be checked. Please tell the nurse if you have any allergies.

You can ask any questions that you have or tell the nurse of any worries. It is not unusual to feel anxious about having a flexible sigmoidoscopy. The nurses and endoscopists understand this and will do their best to reassure you. Once the nurse has finished taking your details, you will be taken to get changed into a hospital gown and dignity shorts ready for the test.

Signing the consent form

You will have been sent a consent form as part of your admissions pack, please read this before your procedure. Please bring this form with you on the day. The endoscopist or senior endoscopy nurse will meet you and talk to you about the procedure. It is important before signing that you understand what is likely to happen. You will be given time to ask any questions that you may feel necessary to make up your mind.

What are the key things to remember?

It is YOUR decision, and you can choose whether to consent to what is being proposed. Ask as many questions as you like and remember to tell the team about anything that concerns you or about any medication, allergies or past medical history which might affect your general health. It may be helpful to make notes before your procedure about anything you want to ask.

The flexible sigmoidoscopy

You will be taken to a treatment room for the procedure and asked to lie on your left side on a trolley. You will be covered with a blanket. The colonoscope is passed through the rectum and lower colon by a trained endoscopist.

You should not feel pain during the test, although you may have brief periods of discomfort, particularly when the endoscope is first inserted and when the scope passes around bends in the bowel.

Occasionally the nurse will press gently on your stomach, or your position may be altered to aid the passage of the scope.

Your bowel will be inflated with a little gas and water, to enable clearer views. This can sometimes be uncomfortable. Please tell the nurse if you have any discomfort. If you do feel discomfort, tell the nurse or doctor and they will change what they are doing to make you feel as comfortable as possible. Pain relief is available if required; this will be Entonox (gas and air).

Entonox® is a mixture of Nitrous Oxide Gas and Oxygen that is inhaled through a mouthpiece. It is an odourless, colourless gas which can provide excellent, short-term pain relief that works quickly and wears off almost as quickly. You will not need to be accompanied home and could drive yourself home afterwards.

Please tell the nurse if you:

• currently have, or have recently had an ear infection, or an operation on your ears
• have, or have recently had, eye surgery
• have recently had a head injury which required you to be in hospital
• have recently been scuba diving
• have recently suffered from a condition causing acute breathing problems (a chest injury, for example, or a collapsed lung)
• have emphysema, or chronic breathing problems, such as chronic bronchitis or moderate to severe asthma.

If you have any of the above conditions, then Entonox® will not be suitable. Having biopsies taken, or polyps removed from the bowel is not usually painful.

Your pulse and oxygen levels will be monitored throughout the procedure. A few people say they find the test embarrassing. The nurse or doctor will do their best to help you feel as relaxed as possible.

How do I get the results?

You will receive the results of the sigmoidoscopy as soon as the test is complete. However, if a sample (biopsy) has been taken, or polyps have been removed, the results will not be available immediately as it will be sent to the laboratory for testing. 

It is essential that you ask the doctors or nurses if you are unclear about any aspect of your care. They will be glad to answer any questions or concerns you may have.

Going home after a flexible sigmoidoscopy

No sedative medications are used during this procedure, so you will be able to make your own way into and home from the Endoscopy Unit. If any treatment is carried out during your flexible sigmoidoscopy, the relevant information will be given to you. A patient information leaflet is given with your discharge information. This can help explain any findings in more detail.

Please note individuals are unable to donate blood for four months after flexible endoscopy and until they have informed the blood service of the diagnosis.

Patients’ property

You are advised not to bring expensive items of jewellery or clothing with you when you visit the Endoscopy Unit.

You will be given a patient property bag to place your clothes in if changing for your procedure.

You will be asked to keep your property with you at all times.

The Endoscopy Unit and Dorset County Hospital NHS Foundation Trust cannot accept responsibility for the safeguarding your property.

We are privileged to be a training hospital

There may be a trainee Endoscopist observing or performing your procedure. If this is the case, there will also be a fully trained accredited Endoscopist present. You will be informed during your admission. You do have the right to decline their participation in your procedure; please let the admitting nurse know of your wishes.

Your appointment time is the time you are expected to arrive in the department. However, you should plan to be in the Endoscopy Unit for three to four hours. The department has three procedure rooms running at the same time also accommodates emergencies. Someone with a later appointment time may be seen before you. If you have any concerns, please ask a member of staff.

Getting here

Car parking across the main hospital site – including the multi-storey car park – operates using automatic number plate recognition.

As you enter our site via Williams Avenue or Damers Road you will need to take a ticket at the barrier to be able to pass through. This also applies if you are dropping off/picking up or a Blue Badge holder.

When you enter the hospital grounds, follow the signs for North Wing Entrance 1. The Endoscopy Unit will be signposted as you enter the main entrance.

Contact numbers

Endoscopy Unit main reception: 01305 255225
Appointment enquiries: 01305 255701
Clinical Advice Line (medical enquiries): 01305 253152

If you call the Clinical Advice Line and your call goes to answer phone, please leave a message with the following details:

• Your name and telephone number
• The procedure you are having
• Date and time of your appointment
• Your reference number (hospital number) or our reference number (NHS number)
• Your query.

Someone will return your call as soon as possible to discuss your telephone message with you.

If you are using hospital transport and your appointment is after 2pm, please contact the appointments line to rearrange an earlier appointment.

About this leaflet

Author: Saffron Flower, Endoscopy Matron and Dinsdale Marjoram
Written: May 2025
Updated and approved: January 2026
Review date: January 2029
Version: v1.4

If you have feedback regarding the accuracy of the information contained in this leaflet, or if you would like a list of references used to develop this leaflet, please email patientinformation.leaflets@dchft.nhs.uk