Colonoscopy & flexible sigmoidoscopy
Why is this investigation being performed?
Your surgeon will have explained to you in the out-patient department the need for this investigation.
Colonoscopy and flexible sigmoidoscopy are usually performed to look at the lining of the bowel and so exclude cancers, polyps, areas of inflammation and other abnormalities. It is usually performed in patients with symptoms.
It can also be performed as a screening test to detect pre-malignant polyps and early cancers in patients without symptoms.
Colonoscopy aims to look at the whole of the large bowel, whilst a flexible sigmoidoscopy only looks as far as the splenic flexure. The splenic flexure is a bend in the bowel under the ribs on the left hand side and is approximately 50-60cm from the anus, about half way around the colon.
What do I need to take beforehand?
Instructions for colonoscopy and flexible sigmoidoscopy will be sent to you several days before the investigation. It is very important that you follow these instructions closely as the bowel has to be as clean as possible. If you do not follow the instructions it may be all a waist of time and have to be repeated.
A colonoscopy requires patients to remain on clear fluids for the immediate 24hrs and to take a purgative to cleanse the bowels. There are a number of purgatives available and individual surgeons have different preferences.
A flexible sigmoidoscopy requires patients to have an enema 1-2 hours before the test. This is something that is performed on the ward. Occasionally, your surgeon will want you to have the same preparation as for a colonoscopy when doing a flexible sigmoidoscopy.
For a colonoscopy: Once in the Endoscopy Unit, patients are asked to lie on their left hand side with their hips and knees bent. A needle is placed in the back of the hand to give intravenous sedation and a pain killer. Supplemental oxygen will be delivered through a small sponge placed in the patient's nostril. A pulse and oxygen monitor is placed on the patient's finger.
Once sedation is given, patients may feel less anxious and possibly sleepy. As the investigation progresses, patients may be asked to change positions eg., lying on their back, right side and occasionally the tummy. This is to facilitate the passage of the telescope around the bowel. The investigation usually takes between 15-40 minutes.
For a flexible sigmoidoscopy: This is similar to the above, but usually does not involve the needle or sedation. Patients usually do not move during the procedure. It is much quicker and usually takes about 10 minutes.
What are the risks?
A colonoscopy requires the insertion of a 1.6m endoscope through the bowel. As with any "invasive" test, there are claerly risks. The risks relate to the complications of either perforation or bleeding.
The absolute risk of perforating the bowel during the investigation is approximately 1 in 3,000. If this does occur, it is highly likely you will require emergency surgery to repair the hole that has been created.
The risk of bleeding usually only occurs if a polyp has been removed. This is something that may settle spontaneously, but once again, can rarely require an operation to rectify the situation.
There are occasionally risks associated with using too much sedation. However, you will be monitored throughout the whole of the procedure, so this is unlikely to occur. There is a miniscule chance of dying associated with a colonoscopy. This is approximately 1 in 10,000, which is about the same as having a general anaesthetic for any procedure.
There are much fewer risks attached to a flexible sigmoidoscopy because in this case we do not aim to go round the whole of bowel. In addition, we do not usually use sedation, unless patients specifically request it. Nonetheless, it is still possible to perforate the bowel, which would also require emergency surgery to repair it.
Is there anything I need to do following the procedure?
If you have not had any sedation for either procedure, then you should be able to return to normal activities very quickly. However, we would still not advise you to return to work the same day as the investigation. If you have had sedation, do not drive or drink alcohol on that day. With or without sedation, patients should usually be able to return to normal activities the following day without any further problems. Remember to drink plenty of water to replace the fluid loss from perging the bowel.
Will I ever need a repeat procedure?
The need for a repeat procedure depends on whether on any abnormalities are found. If a polyp has been removed at colonoscopy, then it is possible that you may grow further polyps in the future. A polyp is a benign growth that may develop into a cancer. Your surgeon will therefore advise you about the need for having a colonoscopy at a future date.
If a polyp is found at flexible sigmoidoscopy it may well be that your surgeon recommends a full colonoscopy relatively soon. This is because it is possible that a small polyp on the left side of the bowel may be associated with further polyps on the right side which would notbe seen during the flexible sigmoidoscopy.