What is colonoscopy?

It is a procedure where the doctor examines the inside of your large bowel using an instrument called a colonoscope or an endoscope. The endoscope is a long flexible tube (about the size of our finger) with a bright light source and lenses at its tip. Images of the lining of our large bowel are transmitted through these lenses to a video screen and this allow your doctors to explain the cause of your symptoms and exclude serious pathology such as colon cancer.

Your physician may recommend a colonoscopic examination if you have a change in bowel habits or experience any rectal bleeding, indicating a possible problem in the colon or rectum. A colonoscopy is also necessary for patients with unexplained abdominal symptoms, positive test results for blood in the stools, with a past history of colonic polyps or cancer and strong a family history of colorectal cancer or polyps. A colonoscopy also allows for the removal of polyps that have been identified on barium examinations.

The bowel must first be thoroughly cleansed before a colonoscopy. This is done the day before the procedure for patients undergoing the procedure in the morning. For colonoscopy performed in the afternoon, bowel preparation may be performed in the same morning. A clean bowel is essential for this procedure. This will increase both the accuracy and safety of the test and also shorten the time needed for the examination. A poor preparation may result in the need for a repeat colonoscopy. Please follow the instructions carefully as there are different regimens for bowel preparation. In general, this involves drinking 2-4 litres of a salty tasting solution, which is a purgative. You will know that you have cleansed your bowel adequately once your liquid stool output appears as a clear and light brown (honey colour) liquid. Your examination may be cancelled if you fail to follow the instructions.

The entire procedure usually takes about 5 to 15 minutes. Before the procedure, you may be given an injection (mild sedative and a painkiller) to make it more comfortable. However, not all patients require the injection as some patients find the procedure tolerable and prefer to participate in the colonoscopy actively. You have a choice and should discuss this with your doctor. During the colonoscopy, you may have a feeling of fullness, as air is introduced to see the inside of the colon. As the bowel passage is not straight, you may also experience mild cramps when the instrument passes around the corners of your colon. Apart from this, the procedure is safe and is usually very well tolerated.

It is possible to take biopsy from any area that looks suspicious for serious pathology. This can be done with the use of forceps that can be introduced through one of the channels in the colonoscope. Secondly, your doctor can also remove most polyps with the colonoscope without the need for abdominal surgery. Polyps can be removed by using a snare - a wire lasso through which an electrical current can be passed to burn the polyp and subsequently remove it. Colonoscopy is more accurate than barium examination of the colon in detecting polyps or early cancers. Removal of potentially malignant polyps is a major step to reduce the risk of colon cancer.

Colonoscopy is a very safe procedure with a less than 0.05% risk of perforation to the wall of the colon. Perforation is a small leak made in the wall of the bowel. Other potential problems may include bleeding from sites where polyps have been removed. Patients with heart valve disease are advised to receive antibiotic prophylaxis as passage of bacteria in the blood maybe caused during colonoscopy. This may subsequently lead to bacterial infection of diseased or artificial heart valves.

Post colonoscopy instructions

You will be asked to rest in the endoscopy unit for about thirty minutes to an hour (depending on whether you have received injection). You will be able to return home and to drive immediately following colonoscopy if no sedation has been given to you. If sedation is given, you should be accompanied home and it is important that you have a quiet rest for the day. The effect of sedation lasts longer than you think so you should not drive a car, operate machinery or drink alcohol for at least 24 hours.

Following the colonoscopy, there may be slight abdominal distension, which quickly improves with the passage of flatus. Most patients can resume their regular diet almost immediately. Any unusual abdominal pain or rectal bleeding within the next three days should be reported immediately.