A Colonoscopy is an examination of the large intestine using a long thin flexible video endoscope
Direct visualization of : polyps, inflammation of bowel wall, abnormal blood vessels(angiodysplasia)
Biopsies can be taken for histology
Most polyps can be removed and treated at the same time
Before the operation
To clean the large intestine of faeces in order to see the inner lining clearly during the colonoscopy, the bowel needs to be cleaned. One method would be:
(i) Only clear fluids(no solid food) must be taken on the day before
(ii) Bowel preparation(eg Picoprep) in the afternoon and evening before a morning procedure(this will cause diarrhoea) or in the evening before and morning of an afternoon procedure
Need to fast for 6 hours before procedure(ie no solid food - one should not have any anyway!). Can have plain water to drink up to 4 hours before the procedure.
Click here for more detailed instructions on how to prepare for your colonoscopy
Day of Procedure
An anaesthetist will put in a drip and give sedation during the procedure.
After the colonoscopy, one will need to be observed in recovery.
Post-procedure : One may feel bloated/pass more flatus/pass small amount of blood(esp if biopsies taken)
Do NOT drive a vehicle/operate machinery/sign any legal documents/work/drink alcohol for 24 hours after (because of sedation being given)
Seek urgent medical attention if : severe abdominal pain/fever/persisting bleeding/black stools/any other concerns.
Perforation - Hole in bowel(1 in 1000; risk incresased if larger polyp removed, adhesions/hysterectomy or cancer present): if so will need surgery
Serious bleeding from bowel(or more rarely bleeding from spleen where colon is attached) (1 in 1000) : may need blood transfusion or an operation. Minor bleeding from trauma to haemorrhoids/bowel wall.
Sepsis/infection; anaesthetic reactions; aspiration/pneumonia; heart attack/stroke; death(1 in 10000)
Incomplete colonoscopy(<5%) because of looping/angulation of bowel- will then need another method of investigation to view the rest of the colon eg Contrast enema or CT colonscopy
Incomplete view - Polyps may be missed / covered by faeculent fluid / faeces / mucosal fold (1-5%)
Other Investigations As Alternatives to Colonoscopy
Contrast (Barium) enema or CT colonoscopy - Advantages: not as invasive, less risks of perforation, shorter waiting time for investigation (especially in public hospitals) Disadvantages: poorer visualization of smaller polyps/mucosal abnormality, exposure to radiation, no views of rectum(need another more limited scope (sigmodoscopy) to look at rectum)
Faecal occult blood test - to screen for polyps and bowel cancer.
Faecal colon cancer DNA test - this will be more common in future as technology improves and cost comes down
Capsule endoscopy - good for imaging the small bowel, especially with persistent bleeding or anaemia despite normal gastroscopy and colonoscopy
Dr LP Cheah also writes at www.colonoscopy.net.au for more Colonoscopy related information.