Colonoscopy
What is Colonoscopy?
A colonoscopy is a diagnostic test that allows evaluation of the lining (mucosa) of the colon. The procedure is performed under anaesthesia in a dedicated suite or operating theatre.
Thorough evaluation requires gaseous distension with CO2 and visual inspection under magnification. Areas of abnormality can be sampled with a biopsy forceps for microscopic examination in the pathology laboratory.
A colonoscope is a flexible fibreoptic camera that has channels for water-flush, suction and an instrument channel. The tip can be directed using handheld controls to help negotiate the length of the colon. Although the tip of the scope allows manouverability, it can still be challenging to negotiate the entire length of the colon which is mobile in some parts, fixed in others and have acute turns called flexures.
When is a Colonoscopy Needed?
Indications include:
- Unexplained rectal bleeding
- Unexplained Iron deficiency anaemia
- Altered bowel habit (looser and/or more frequent) greater than six weeks duration
- Family history of colorectal cancer
- Abnormal imaging
- Suspected inflammatory bowel disease
Bowel Preparation
Prior to your procedure you will be given instructions on how to prepare your bowel so that optimal views are obtained. This is done by evacuating residual stool from the colon. The better the bowel prep, the clearer the images and less likely it is for smaller lesions or abnormalities to be missed.
Bowel prep requires drinking clear fluids the day prior to the procedure and drinking 1 litre of laxative solution the night prior and the morning of your colonoscopy.
What are Polyps?
Polyps are fleshy overgrowths arising from the lining of the bowel. Left untreated for years, polyps have the potential to become cancerous. Most polyps can be removed at the time of colonoscopy using a snare (pictured).
Polyps that are removed are sent for microscopic examination. Depending on the type and number of polyps, follow-up colonoscopies may be required for post-procedure surveillance.
If a polyp turns out to be a cancerous polyp a surgical resection of that part of the bowel may be indicated following review in a multidisciplinary team meeting of surgeons, pathologists, oncologists and radiologists.
Anticoagulants
If you normally take blood thinners such as Clopidogrel or Apixaban it is very important to closely follow your instructions on when to stop them pre-procedure. This is to give your body enough time to metabolise and clear the medication so your blood can form clots efficiently on the day of the procedure. This is to reduce the risk of bleeding post-procedure, particularly if polypectomy is performed.
Diverticular Disease
This image demonstrates a fairly common finding called diverticular disease. Instead of the colon having a smooth appearance in between its usual folds, there are multiple pouches or pockets called diverticuli.
Diverticular disease can result in lower abdominal pain and potentially attacks of infections/inflammation called 'diverticulitis'.
Colorectal Cancer
If a lesion is discovered that is highly suspicious of cancer, samples or biopsies will be taken for microscopy. You will be informed post-procedure and staging scans will be arranged to occur within the next week or two.
You will then be brought back to clinic to discuss the results and make a plan moving forward.
We realise this is a big fear with colonoscopy, but thankfully it is not a common finding. In addition to this, colorectal cancer can have a favourable prognosis with modern management, when detected early.
Haemorrhoid Banding
At the time of you colonoscopy. Rubber band ligation (RBL) can be performed to treat non-prolapsing internal haemorrhoids to reduce bleeding. The rubber bands work by constricting blood supply to the haemorrhoids so they eventually shrink. You may experience a discomfort around your back passage and some bleeding after this procedure but they settle with time.
Post-Procedure
After a period of recovery from anaesthetic you will need a responsible adult to take you home as you cannot drive after an anaesthetic. You may experience some bloating initially which will settle as the CO2 is reabsorbed and/or passed as flatus.
You will be advised on when to restart your blood-thinners if you normally take them and can go back to a normal diet, unless otherwise instructed.
The image on the left demonstrates a common finding called diverticular disease. This results in multiple pouches or pockets called diverticuli which is a sign of wear and tear of the bowel. The condition can result in lower abdominal pain and even result in attacks of infections called diverticulitis.
Surveillance
Cancer Society guidelines recommend when to perform surveillance colonoscopy, which depends on the number, size and subtype of polyps removed