Colonoscopy and sigmoidoscopy



In his current practice, Mr Williams manages all general surgical and colorectal patients.  This usually starts with a consultation in the out-patient clinic.  Subsequent investigations may be by endoscopy or X-rays.  

Mr Williams is a fully trained endoscopist having performed many of the lists that were required in the pilot phases of what is now the national bowel cancer screening program.  

Colonoscopy for screening requires a greater level of skill and competence.  This was formally validated after a one-to-one masterclass at St Marks hospital in 2004.  

He has continued to develop his endoscopic expertise and was recently (2010) revalidated by undertaking a further advanced course overseen by the Joint Advisory Group on Endoscopy



A colonoscopy is a ‘camera test’ that allows visual inspection of the colon (large bowel) using a specialised fibreoptic instrument.  For most patients with bowel symptoms (diarrhoea, constipation, abdominal bloating, abdominal pain) a colonoscopy is usually the initial diagnostic test that is performed in order to determine the cause of their symptoms.  

When arranging for such a test, you will be informed of the date and will receive a package containing the following: diet sheet, information sheet, laxatives, itinerary for the laxatives. Several days before the test, you are asked to adjust your diet to that from the list of foods that are allowed (and foods to avoid!).  This is to reduce the faecal bulk within the colon.  The day before your test, you are instructed to take laxatives that are sent to you based on the itinerary.  This is to empty the bowel completely so that the surface lining can be inspected.  If the instructions are not clear, the information pack sent to you will contain a contact telephone number to the Endoscopy department for further advice and clarification.

On the day of the test, you will attend the hospital at the pre-arranged time.  You will be admitted by a nurse, who will take you through some questions about your general health and to facilitate your care throughout the process.  A cannula (a very small plastic tube) is placed in a vein for administering the painkiller and sedative that is usually required for the examination.  This access also allows for you to be given further drugs as necessary.  The examination takes place in a specially equipped room.  You will have a nurse monitoring your vital signs and another nurse will be available to help with the examination. 

The endoscope is then passed through the bottom and into bowel.  The instrument is then carefully passed all the way around the colon.  The colon can very tortuous and so the procedure can sometimes take up to 45 minutes but an average time would be 20-30 minutes for the camera to be inspecting the bowel.  During the procedure, you made be asked to change your position as this alters the lie of the colon and can facilitate the passage of the endoscope around the colon.  The careful visual inspection will usually take place as the camera is withdrawn.  It is well documented that this part of the examination should take about 10 minutes.  Any quicker, and there is a greater risk of missing something. 

If there is an abnormality seen in the bowel, the options are either to try and remove it, if it is safe to do so, or to take a biopsy ( a small sample) that can then be sent to be examined under a microscope.  There are some circumstances where it is useful to take samples at differing locations around the bowel.  Your doctor should advise you of this at the initial consultation.

After the procedure, you are taken to a recovery area where you will be monitored as the sedative drugs are ‘wearing off’.  As soon as you are comfortable and awake you will then be offered fluids and a light snack.  You are then ready for home!

Because of the drugs that are administered, YOU SHOULD NOT DRIVE for 48 hours.

Flexible sigmoidoscopy

A fibreoptic sigmoidoscopy (FOS) is similar to a colonoscopy but the examination is specifically focus on the left side of the large bowel.  As it is a less involved procedure, you will not generally require laxatives.  There will be dietary changes to try and empty the bowel.  On the day of the test, after admission to the hospital, a small enema will be administered in order to empty the lower bowel.  After this, the camera test can then take place.

Endoscopy patient information sheets