Preparing for a colonoscopy procedure

Preparing for a colonoscopy procedure

It is reassuring to know what to expect from any medical examination before you actually go. It means you can prepare both physically and mentally to minimise unnecessary stress and to ensure the test results will be as accurate as possible. The colonoscopy examination is used to detect colon cancer or other abnormalities in the colon. Learn what to expect in advance and on the day of the test.

The day before

In order for the colon to be as clean as possible, you will be prescribed a powerful laxative to ensure that the view of the endoscope during the examination will be as good as possible.

Whilst it isn’t the most pleasant experience, it is absolutely essential to the colonoscopy examination, for the best chance of success.

On arrival

When arriving at the outpatient unit, you will be welcomed by a nurse, who will:

  • take your weight and height
  • check all your personal details to ensure they are correct
  • give you a wristband with your details on it
  • show you where to wait for the doctor

The doctor will then:

  • also check your details
  • answer any questions you may have
  • discuss any risks
  • go through the consent form with you, which needs to be signed-off before the procedure can go ahead
  • take you into the endoscopy room, either walking or wheeled on a bed



Normally only sedation is required in advance of a colonoscopy procedure, however a general anaesthetic is available for some people if requested.

A small drip is placed into a vein to enable an intravenous drug to be administered; midazolam and fentanyl are the most common.

Test 1 – rectal examination

Before the colonoscopy part of the procedure, the doctor will conduct a rectal examination using a lubricated, gloved index finger.

It requires you to lie on your left side with your knees bent and it is optional if you want to see what is happening by looking at the monitor.


Test 2 – colonoscopy

The colonoscopy allows the doctor to explore the colon using a 120cm long endoscope with a bright light to navigate through the twists and turns of the colon.

(1) At some points, you may be required to turn on your back with your knees bent, to enable easier movement of the endoscope.

(2) When the scope reaches the end of the colon, called the caecum, the doctor passes the scope into the small bowel, also known as the terminal ileum. This is a key place to detect Crohn’s disease inflammation.

(3) From here, the doctor will slowly remove the camera, whilst looking for any abnormalities. It is during this part of the process that the doctor may take tiny biopsies, which you won’t feel as the inner lining of the colon doesn’t have any sensory receptors.

(4) Also, any bowel polyps may be removed as the endoscope is returning down the colon. This is done by using a channel down the side of the endoscope that can place a loop around the polyp, cutting it off painlessly.

This whole process can take up to 10 minutes, but it does vary depending on what the doctor finds and the ease of movement through the colon.



Bleeding is usually minimal however, it can occur, as can mild abdominal pain. Any pain or bleeding that does not go away, or worsens requires you to return to hospital to get checked.

It is important to have someone to collect you after the examination as you will not be able to drive a car following a colonoscopy.


Further help

For more information about preparing for a colonoscopy, download our full Guide here. 

A specialist gastroenterologist will be able to answer any questions and reassure you by discussing the procedure in more detail.



Important information