Colonoscopy is a procedure for visualisation of the lower gastrointestinal tract namely the anal canal, rectum and colon. It is performed with a help of a colonoscope which is a flexible tube with a camera at its tip which can be inserted through the anus and manoeuvred through the colon till the last part of the small intestine. It is indicated for diagnosis, biopsy as well as treatment of certain disorders involving this part of the GI tract.
The indications for colonoscopy are chronic lower abdominal pain not amenable to medication, chronic constipation, lower GI bleeding, inflammatory bowel disease, unexplained weight loss and any noticeable and persistent change in bowel habits. It may be indicated as part of screening in high risk individuals particularly patients with personal or family history of colorectal, evaluation of diverticular disease and biopsy of lesions or masses in the lower GI tract. It can be used for endoscopic resection of polyps and early submucosal tumours, for coring or haemostasis of advanced tumours with argon laser and endoscopic stenting for bypass of obstructing masses in the lower GI tract.
A colonoscopy requires prior bowel preparation by giving laxatives to cleanse the colon of stool which are usually administered the evening and night before the procedure. This includes liquid laxatives which cause a moderate degree of diarrhoea and enemas to evacuate faecal matter from the rectum. Because the procedure causes some discomfort, it is usually carried out under moderate sedation but the patient can be sent home after 1-2 hours.