What is endoscopy? 

Endoscopy is a minimally invasive procedure which examines the inside of the digestive tract using an endoscope, a long thin flexible tube with a tiny camera attached at the end. Colonoscopy is a type of endoscopy which examines the inside lining of the large intestine.

Why is colonoscopy done? 

Colonoscopy may be recommended for:

  • Investigation of symptoms such as abdominal pain, altered bowel habits, chronic constipation, chronic diarrhoea, rectal bleeding and weight loss
  • Screening for colorectal cancer 
  • Surveillance for polyps & cancer if personal history of polyps or cancer 

Colonoscopy is considered to provide the most accurate assessment of the colon. However, no test is perfect and there is a risk that an abnormality may not be detected. A colonoscopy can miss lesions in around 5% of cases. 

How do I prepare for colonoscopy? 

  • Bowel preparation. You will need to follow a special diet and take bowel preparation medication before your procedure. Printed instructions will be provided at time of your booking (or click here to download instructions).

  • Fasting. You will need to stop drinking and eating for approximately 6 hours before the procedure. The hospital will contact you 1 working day prior to your procedure to advise fasting time. 

  • Stop taking certain medications. You will need to stop taking certain blood thinning medications in the days before your procedure. 

How is colonoscopy performed? 

Colonoscopy is performed under a light anaesthetic (sedation). A sedative medication is given through a vein in your forearm. Once sedated and lying in a comfortable position on your left side, the endoscope is passed through the anus and guided through the colon. Once the endoscope has reached the opening to the small intestine, it is slowly withdrawn and the lining of the colon is examined again. In some patients, it may not be possible to navigate the endoscope through the full length of the colon - in such cases further tests may be required. 


If abnormal tissue is seen during the procedure, a biopsy (a small piece of tissue) may be taken by forceps passed through the endoscope. The tissue is sent to a pathologist for examination under a microscope.  


A polyp is a non-cancerous growth on the inside lining of the colon. They vary in size from one millimetre to a few centimetres and can develop into cancer if left untreated. If a polyp is seen during the procedure, it may be removed using special instruments passed through the endoscope. The tissue is sent to a pathologist for examination under a microscope. Sometimes a polyp may not be removed endoscopically because it is too large or too difficult to reach - in such cases surgery may be required. 

What happens after colonoscopy?

You will be monitored in the recovery area until the effects of the sedative medication have worn off. You may feel bloated because of the air inserted during the procedure and this will pass over the next few hours. Rarely, you may pass a small amount of blood, especially if biopsies are performed.

Because of the sedation given, it is important that you do not drive, operate machinery, drink alcohol or make important decisions on the same day of the procedure. A friend or relative will be required to take you home. Full recovery is expected by the next day. 

Dr Ling will inform you of your test results on the day of the procedure. A follow-up appointment may be made to discuss the test results more fully. The results of any biopsies will usually take 1 week. 

What are potential complications of colonoscopy? 

Colonoscopy is a safe procedure. Despite the highest standard of practice, complications can occur. The following possible complications are listed to inform not to alarm. There may be other complications that are not listed. 

  • Bleeding
  • Infection
  • Perforation of the colon ​

Dr Mary Ling has undergone recertification by the Gastroenterological Society of Australia (GESA) to perform colonoscopy. Dr Ling performs colonoscopy at Brisbane Waters Private Hospital, Gosford Private Endoscopy Centre and Tuggerah Lakes Private Hospital on the Central Coast.

Related Information

Bowel Preparation
Rapid Access Endoscopy