What is Colonoscopy?
A colonscope is an endoscope that is used to evaluate the rectum and colon. It is inserted through the anus and then rectum, colon and occasionally the small intestine (ileum). Indications would be to evaluate for disease of the rectum and colon and sometimes small intestine. These would include infections, inflammation, polyps and cancer. These would manifest with symptoms such as blood in the stools, looseness of stools, lower abdominal pain, bloating or constipation.
Before colonoscopy, you will need bowel preparation. Your doctor may instruct you to take some of your existing medicines (e.g. medicines of high blood pressure, asthma etc.) and omit other medicines (e.g. diabetic medicines, anti-platelets, anti-coagulants etc.).
In the endoscopy room, a cannula will be inserted into a vein, sedative will be given through this route and you will fall asleep. After this, the procedure will be commenced. The scope is inserted via. your anus into your rectum, colon and if required, small intestine. Air will be used to distend the bowel (an air channel is built into the scope) so that we can see clearly. Suction is also available (built into the scope) so that fluid can be sucked out. If any abnormality is seen (e.g. ulcer, colitis or cancer), a small bite of tissue (about 1-2 mm) can be retrieved with a biopsy forceps for microscopic examination. Larger polyps can also be removed (snared) for microscopic examination.
After the procedure, you will be monitored for 1-2 hours before you are ready for discharge. Do not drive or operate machinery for make important decisions for 24 hours as the sedatives will affect your judgement. Please also make arrangements for someone to bring you home.
Your doctor will be able to tell you his findings immediately. If a biopsy has been taken, the results should be ready in 2-3 days. Sometimes if the scope is normal and so cannot explain your symptoms, your doctor may recommend additional tests such as an ultrasound or CT scan.
Colonoscopy is considered the most accurate examination of the colon and rectum and is used both as a diagnostic and screening tool. It is a very safe procedure and in screening has a less than 1 in 1000 risk of a major complication such as bleeding or perforation.
Who should go for colorectal cancer screening?
Colorectal cancer may occur at any adult age but most patients are over the age of 50 yrs. Screening should thus begin at 50 yrs. and include a stool occult blood test (yearly) and colonoscopy (every 5 years).
People with increased-risk
- People who have one or more close relatives diagnosed with colorectal cancer- should have colonoscopy at an age 10 years earlier than the age their relative developed the cancer, yearly faecal occult blood testing (FOBT) after that and colonoscopy every 3-5 years.
- Those with personal history of polyps or colorectal cancer or inflammatory bowel disease.
- People with breast, gastro-intestinal or gynaecological cancer.