Colonoscopy: What It Is and What to Expect
What is a Colonoscopy?
The word colonoscopy comes from “colono” (meaning colon or large bowel) and “scopy” (meaning to look or examine).
A colonoscopy is a procedure where a thin, flexible tube with a camera is used to examine the large bowel (colon) and rectum.
During the procedure, the colonoscope is gently passed through the back passage (anus) and advanced through the entire colon, allowing a careful examination of the inner lining.
Why?
Your doctor may recommend a colonoscopy to investigate bowel symptoms or as part of routine screening for bowel cancer and polyps.
Common reasons include:
Rectal bleeding or blood in the stool
Persistent changes in bowel habits (diarrhoea, constipation)
Abdominal pain or bloating
Unexplained anaemia or low iron levels
Family history of bowel cancer or polyps
Surveillance after previous polyp removal or bowel surgery
The procedure can detect polyps, inflammation, or early cancer, allowing your doctor to remove or treat these issues before they cause problems.
What Happens During the Procedure?
A colonoscopy is a safe and commonly performed day procedure.
Before the test, you’ll need to follow a bowel preparation to clear the colon. This involves drinking a special solution the day before the procedure to ensure the bowel is clean for clear visibility.
At the hospital or endoscopy centre:
You’ll change into a gown and have a cannula placed for sedation.
You’ll receive light sedation, helping you relax or fall asleep — most patients do not remember the procedure.
The colonoscope is inserted through the back passage and advanced through the colon while the doctor examines the lining on a high-definition screen.
Small tissue samples (biopsies) may be taken, and polyps can often be removed at the same time — this is painless.
The procedure usually takes about 20 to 30 minutes. Afterwards, you’ll rest until the sedation wears off, and a friend or family member will need to take you home.
Are There Any Risks?
A colonoscopy is considered a very safe procedure, but all procedures carry some risk. These are uncommon and usually minor.
Possible risks include:
Abdominal discomfort or bloating for a few hours afterwards
Reaction to sedation (temporary drowsiness or nausea)
Bleeding, especially if a polyp is removed — usually minor and self-limiting
Perforation (tear) of the bowel wall — very rare
Other specific risks may depend on your medical history, and your doctor will discuss these with you before the procedure.
Authored by Dr Walid Abu Shawish MBBS(Hons) BPharm(Hons) PGCertClinPharm FRACP.
Windsor, Melbourne Located Private Gastroenterologist & Advanced Endoscopist. For referral or contact information click here.