A colonoscopy is an examination of the large intestines which includes the rectum and colon as well as the end portion of the small intestine. A colonoscope, which is a flexible lighted instrument that projects a video image onto an external monitor, is inserted through the anus and carefully maneuvered by the surgeon. This allows him to visualize the lumen (internal view) of the large intestine and in turn allows him to evaluate for any abnormalities such as polyps, cancerous growths or other changes to the mucosal lining. When these are detected, the surgeon can remove the polyp or sample the tissue for a detailed histological examination.
Colorectal cancer is the most common cancer in Singapore. The Ministry of Health Singapore (MOH) guidelines defines the average-risk individual as one who does not have any symptoms of colorectal cancer or family history with relatives that have had colorectal cancer. While this individual has a 5% lifetime risk of developing colorectal cancer, the risk increases with age. World-wide studies have shown that early detection of cancer and the removal of polyps can save lives. Hence, the current recommendation is for colonoscopy screening to begin from the age of 50 years.
For individuals at a higher risk for colorectal cancer, the recommendation is for colonoscopy screening to take place 10 years prior to youngest case in the family or age 40 years (whichever is earlier).
It is easy for patients to get certain symptoms of colon cancer confused with similar symptoms caused by other gastrointestinal conditions such as inflammatory bowel disease (IBS), haemorrhoids or other forms of gastrointestinal infection. Such similar symptoms include:
When colon cancer is the cause of these symptoms, it is usually the case that the cancer has already spread and become somewhat advanced. Hence, it is important to test for colon cancer before any symptoms emerge. If you go for a colonoscopy and find pre-cancerous growths (known as polyps) and have them removed, you might be able to stunt the development of certain colon or colorectal cancers.
Depending on the risk features of previous polyps, a repeat colonoscopy is recommended between 1 to 3 years after the last polypectomy.
Colonoscopy is recommended 1 year after resection and 3 yearly thereafter.
Any form of colorectal screening is demonstrated to be cost-effective compared to no screening. The best method of screening is controversial and difficult to determine. Various methods ranging from serum tumour marker, faecal occult blood testing, barium enema to CT colonography are available. However, when considering patient compliance and accuracy, getting a colonscopy once or twice in your lifetime appears to have the best acceptance and accuracy.
You will be given a bowel prep solution to drink on the night before or the morning of the procedure. This will result in repeated large bowel movements to clear the large intestine of faecal material. It is best to also avoid a high-fibre diet 3 days before the colonoscopy. You should also inform the surgeon if you have any drug allergies or are taking any blood-thinning medications as these may have to be stopped in advance.
You will be placed on your side with your knees drawn toward your chest. Medications will be given through an IV line to help you relax and remain comfortable. You may or may not fall completely asleep during the colonoscopy, but most patients will not be able to remember the procedure. Some monitoring devices will be attached to your body during the examination. The whole procedure should take 20 to 30 minutes during which you may experience abdominal bloating. The nurse may apply occasional pressure with her hand on your abdomen to assist in the procedure.
When the procedure is completed, you will be transferred back to the recovery ward where monitoring continues while you recover from the sedation. As flatus is passed, you will feel less bloated/distended. When you are fully awake and comfortable, you will be given a drink and some food. It is strongly recommended that you have someone to accompany you home after the procedure.
Colonoscopy is a very common day surgery procedure and major complications are rare.
Should these occur, it is important to contact your surgeon urgently so that follow-up measures may be undertaken expediently.
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