Preparation for Colonoscopy and Gastroscopy

How to Prepare for Colonoscopy and Gastroscopy

Learn how you can prepare for and what to expect during scope procedures such as Colonoscopy and OGD (Oesophagoscopy, Gastroscopy and Duodenoscopy).

Colonoscopy is used to detect colorectal cancer (also known as colon cancer). A doctor may recommend this scope procedure if a patient has/requires:

  • Change in bowel habits
  • Familial colorectal polyposis
  • Screening for polyps or having a family history of colorectal cancer
  • Haemorrhoids
  • Rectal bleeding
  • Anaemia or decrease in the amount of red blood cells
  • Blood in stools (or when tested positive during Faecal Occult Blood Testing/FOBT)

OGD procedures (referring to Oesophagoscopy, Gastroscopy and Duodenoscopy) are used to screen for ulcers, gastritis and cancer in the upper digestive tract.

Apart from screening, treatment can also be administered during OGD by:

  • Applying treatment to a bleeding ulcer to stop the bleeding
  • Removing polyps or foreign bodies
  • Treating enlarged blood vessels in the food pipe (oesophagus) by tying them up

How to prepare for a scope

For colonoscopy, performing bowel cleansing before the procedure is required. However, for OGD, fasting for 6 hours (without food and drink) is needed.

Improper preparation may result in patients having to repeat or reschedule their scope procedure.

Bowel Cleansing for Colonoscopy

There are two methods of colon cleansing – Oral Fleet and Fortrans (or PEG powder). Your doctor will decide which is suitable for you.

How to prepare Oral Fleet: Usually 2 bottles of Oral Fleet are given for colon cleansing. Each bottle contains 45ml of medicine and each is to be taken half an hour apart. Divide each bottle into 15ml by pouring into 3 glasses. Fill each glass with approximately 250ml of plain water. You can also add honey, glucose, barley water or isotonic drinks to flavour the solution. Drink all 3 glasses over 10mins. Repeat for the second bottle of Oral Fleet.

How to prepare Fortrans (PEG powder): Your doctor will decide the number of packets you require. Dilute 1 packet with 1 litre of plain water. Drink it over a 1 hour period.

Once you feel the bowel preparation mix taking effect, stay close to the bathroom.

Tips to reduce discomfort of a scope

For Colonoscopy: 3 days before the procedure, try to avoid fruits and vegetables, red meat and brown rice.

If your scope is scheduled for the morning, have a soft diet 1 day before the procedure and consume clear liquids only.

If your scope is scheduled for the afternoon, have a light breakfast and clear liquids only.

For OGD: If you feel thirsty during the 6-hour fast, rinse your mouth with water or suck on some ice cubes.

While preparing for a colonoscopy or OGD, you may be asked to stop certain medications depending on your doctor’s advice.

Medications to continue: Hypertensive/thyroid

Medications to discontinue: Blood thinning medicine, iron tablets, and medication for diabetes on the day of the procedure (only for colonoscopy)

After your procedure, you can return home immediately if no sedation was given. If sedation was given, you will be required to be accompanied home by an adult.

Procedure Room @ MWH Medical Specialist Centre
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