Overview
During a colonoscopy, a thin, flexible tube with a tiny camera on the end is gently guided through your back passage to look at the entire lining of your large bowel. You will be sedated (given medication to make you drowsy and comfortable), so you will not be aware of most of the procedure. It usually takes between 20 and 45 minutes. If anything needs attention — such as a polyp (a small growth on the bowel wall) — Mr Nguyen can remove it or take a sample at the same time, meaning no separate procedure is needed.
Who needs this procedure?
Your GP or specialist may recommend a colonoscopy if you have any of the following:
- Bowel cancer screening — whether you are at average risk (e.g. you are over 45) or higher risk because of a family history of bowel cancer or polyps, or because a home stool test (FOBT — faecal occult blood test) came back positive
- Rectal bleeding (blood on or in your stool) or iron deficiency anaemia (low iron levels that are not explained by your diet)
- A change in your bowel habits — such as looser stools, constipation, or altered frequency — lasting more than four to six weeks
- Follow-up after previous polyps or bowel cancer, to make sure nothing new has developed
- Assessment or monitoring of inflammatory bowel disease (IBD), such as Crohn's disease or ulcerative colitis
- Unexplained abdominal symptoms, such as pain or bloating, that have not resolved with other investigations
Benefits
- Gives a clear, direct view of your entire large bowel — more thorough than a CT scan of the bowel (CT colonography), which cannot treat anything it finds
- Any polyps (small growths) found can be removed on the spot, and tissue samples can be taken for analysis — all in the same appointment
- Most people go home the same day and are back to normal activities the next morning
- Very accurate — colonoscopy is the gold standard for detecting bowel polyps and remains more thorough than any imaging alternative
- Combines diagnosis and treatment in one procedure, so you avoid a second appointment if something is found
- Usually covered by Medicare when your doctor has recommended it for a clinical reason
Risks & considerations
Serious complications from colonoscopy are uncommon, but it is important that you understand what they are so you can make an informed decision. Mr Nguyen will talk through these with you before your procedure.
- Perforation (a small tear in the bowel wall) — this is rare, occurring in roughly 1 in every 1,000 colonoscopies. The risk is slightly higher if a polyp is removed at the same time. If it does happen, it is usually identified and managed promptly, and may require further treatment.
- Bleeding after polyp removal — a small amount of bleeding occurs in around 1 to 2 in every 100 polypectomies (polyp removal procedures). In most cases this can be treated during the same procedure or settles on its own. Heavy or ongoing bleeding is uncommon.
- Missed lesions — no camera examination is perfect. Very small polyps (under a few millimetres) may occasionally be missed; the miss rate for small polyps is approximately 6–10%. This is why follow-up colonoscopies are scheduled if you are in a higher-risk group.
- Sedation effects — serious reactions to sedation are rare. You may feel drowsy or a little groggy for several hours afterwards, which is why you need someone to drive you home.
- Bloating and cramping afterwards — this is very common and is caused by the air used to inflate the bowel during the procedure. It usually settles within a few hours.
- Incomplete procedure — on rare occasions it is not possible to reach the full length of the bowel in a single examination. In Mr Nguyen's practice this happens in fewer than 1 in 100 cases. If it does occur, a CT colonography (a scan of the bowel) will be arranged to complete the assessment.
Before the procedure
Food: You can eat normally up until 6 hours before your admission time. After that, nothing to eat at all — if you eat closer to the procedure, it may need to be cancelled for your safety.
Clear fluids: You can drink clear fluids up until 2 hours before your admission time. Clear fluids include: water (still or sparkling), clear broth or Bonox, pulp-free juice, plain cordial or lemonade, plain jelly or ice blocks, orange or yellow Gatorade or Powerade (good for keeping your electrolytes up), and black tea or coffee with a small splash of milk. Avoid red, purple, or green coloured drinks — these can stain the bowel lining and make it harder for Mr Nguyen to see clearly.
Medications: Take all your regular medications as normal, with a small sip of water. Do not chew gum on the day of your procedure.
Supplements: Stop all non-prescribed vitamins, minerals, and herbal supplements (including fish oil, glucosamine, and vitamin E) at least 5 days before your procedure. Stop iron tablets at least 7 days before — iron can coat the bowel lining and obscure the view.
Blood thinners: If you take warfarin, rivaroxaban (Xarelto), apixaban (Eliquis), dabigatran (Pradaxa) or clopidogrel, please call Mr Nguyen’s rooms before your procedure — these medications may need to be paused or adjusted beforehand.
Diabetes medications: If you take tablets or injections for diabetes (such as Metformin, Diamicron, Jardiance, or Forxiga), stop these 2 days before your procedure. Do not stop insulin on your own — call our rooms and we will give you personalised instructions for your dose.
Weight loss injections (GLP-1 medications): If you take semaglutide (Ozempic or Wegovy), liraglutide (Saxenda), dulaglutide (Trulicity), or a similar medication, you will need to stay on clear fluids for the full 24 hours before your admission time. You do not need to stop your medication. Please let Mr Nguyen’s rooms know when you book.
Mr Nguyen's preferred bowel preparation is Picoprep (a laxative solution), taken as three sachets spread across the day before and the morning of your procedure. This "split prep" approach is gentler on your system and usually gives a better result than taking everything the night before. The schedule below is for a morning procedure. If you have an afternoon procedure, or if you have been given a different preparation, please refer to the Full Bowel Preparation Guide or call our rooms.
2–3 days before: Eat a low-fibre diet — white bread, white rice, plain pasta, eggs, skinless chicken or fish, plain yoghurt. Avoid wholegrains, most fruit and vegetables, nuts, seeds, and legumes. This reduces the amount of residue in your bowel and makes the preparation easier.
Day before — until 3pm: Continue with white, low-fibre foods only (as above).
Day before — after 3pm: Clear fluids only from this point. No solid food. Avoid red, purple, or green drinks.
Day before — 5pm: Take your first sachet of Picoprep, dissolved in water as directed on the packet. Stay close to a bathroom — your bowels are likely to start moving within one to three hours.
Day before — 8pm: Take your second sachet of Picoprep. Continue drinking clear fluids throughout the evening to stay hydrated.
Morning of your procedure — 5am: Take your third and final sachet of Picoprep, followed by three to four glasses of clear fluid. Take any regular morning medications with a small sip of water. By the end of the preparation, your bowel motions should be clear or pale yellow — this means the preparation has worked. Stop all fluids two hours before your scheduled arrival time — nothing by mouth from that point.
Everyone's bowel reacts differently to preparation. If you develop significant nausea, vomiting, or cannot tolerate the preparation, call Mr Nguyen's rooms before stopping — we can help.
On the day
- Make sure you have arranged for a responsible adult to drive you home — because of the sedation, you cannot drive or operate machinery for the rest of the day, even if you feel fine
- When you arrive at the endoscopy unit, you will check in at reception and a nurse will go through a short assessment with you, check your details, and answer any last-minute questions
- A small cannula (thin plastic tube) is inserted into a vein in your arm, and sedation is given by an anaesthetist or specially trained nurse. Most people have no memory of the procedure at all
- The colonoscope (a thin, flexible camera tube) is guided gently through your back passage, and Mr Nguyen carefully examines the full length of your large bowel
- If any polyps are found, they are removed at the same time — you will not feel this
- The whole procedure usually takes between 20 and 45 minutes. You will then rest in the day-stay recovery area for one to two hours while the sedation wears off
- Before you leave, Mr Nguyen or a member of the team will sit down with you and explain what was found. You will be given a written copy of the endoscopy report to take home
- If any tissue samples (biopsies) or removed polyps are sent to the laboratory for analysis, the results are usually back within two to six weeks. Mr Nguyen will discuss these with you at a follow-up telehealth (phone or video) review — at no charge for endoscopy patients. If anything concerning is found, or if further treatment may be needed, the review will happen sooner and in person. You are always welcome to request an in-person appointment if you would prefer that
Recovery & aftercare
- On the day: Rest at home. The sedation can leave you feeling drowsy for several hours, and your judgement may be temporarily affected — this is normal and will pass
- The next day: You can eat normally and get back to your usual activities. Some bloating and mild cramping is very common after a colonoscopy and usually settles by the end of the day
- Do not drive or drink alcohol for 24 hours after receiving sedation, even if you feel fully alert
- If a polyp was removed during your procedure, you do not need to restrict your activities — you can go back to your normal routine straight away. You may occasionally notice a very small amount of blood in your stool, which is not a cause for concern. However, if you experience heavy rectal bleeding that does not settle quickly, please contact the hospital or get in touch with Mr Nguyen using the contact details below
- When your next colonoscopy is due will depend on what was found. If low-risk polyps (adenomas — the kind that can slowly turn into cancer over time) were removed, the next check is typically in five years. Mr Nguyen will give you a personalised recommendation before you leave
- A follow-up review with Mr Nguyen is arranged within two to six weeks of your procedure. For endoscopy patients, this is usually a phone or telehealth appointment at no charge. If an in-rooms appointment is needed — for example, to discuss further treatment — a standard consultation fee applies
Related patient guides
These articles have been written to answer the questions patients most commonly ask about colonoscopy — before, during, and after the procedure.
Do I Need a Colonoscopy?
What to Expect from Your First Colonoscopy
How Do I Prepare for a Colonoscopy?
How Painful is a Colonoscopy?
What Happens During a Colonoscopy
What Can I Eat After a Colonoscopy?
Can I Eat Before a Colonoscopy?
Colonoscopy vs CT Colonography
What Happens If Polyps Are Found During a Colonoscopy?
What Does a Positive FOBT Mean?
Bowel Cancer Screening in Australia
When Should You Have a Colonoscopy?
When Should You Start Bowel Cancer Screening?
Have questions about your colonoscopy? Mr Nguyen sees patients in Heidelberg and performs procedures at Austin Health, Warringal Private Hospital and Epworth Eastern. You are welcome to call us on (03) 9816 3951, email admin@northeasternsurgical.com.au, or send an enquiry online →