Health Information and Tools > Patient Care Handouts >  Colonoscopy: Before Your Procedure

Main Content

Colonoscopy: Before Your Procedure

Picture of normal colon and colon polyp

What is a colonoscopy?

A colonoscopy is a test that lets a doctor look inside your colon. The doctor uses a thin, lighted tube called a colonoscope to look for problems. These include small growths called polyps, cancer, or bleeding.

During the test, the doctor can take samples of tissue that can be checked for cancer or other problems. This is called a biopsy. The doctor can also take out polyps.

Before the test, you will need to stop eating solid foods. You also will drink a liquid (laxative) solution that cleans out your colon. This helps your doctor be able to see inside your colon during the test.

How do you prepare for the procedure?

Procedures can be stressful. This information will help you understand what you can expect. And it will help you safely prepare for your procedure.

Preparing for the procedure

  • Understand exactly what procedure is planned, along with the risks, benefits, and other options.
  • Tell your doctors ALL the medicines and natural health products you take. Some of these can increase the risk of bleeding or interact with the sedation medicine.
  • If you take aspirin or some other blood thinners, be sure to talk to your doctor. They will tell you if you should stop taking these medicines before your procedure. Make sure that you understand exactly what your doctor wants you to do.
  • Your doctor will tell you which medicines to take or stop before your procedure. You may need to stop taking certain medicines a week or more before the procedure. So talk to your doctor as soon as you can.
  • If you have an advance care plan, let your doctor know. Bring a copy to the hospital. If you don't have one, you may want to prepare one. It lets your doctor and loved ones know your health care wishes. Doctors advise that everyone prepare these papers before any type of surgery or procedure.
  • If you have sedation be sure you have someone to drive you home. Sedation medicine makes it unsafe for you to drive.

Before the procedure

  • Follow your doctor's directions about when to stop eating solid foods and drink only clear liquids. You can drink water, clear juices, clear broths, flavoured ice pops, and gelatin (such as Jell-O). Do not eat or drink anything red, purple, or blue. This includes grape juice and grape-flavoured ice pops. It also includes fruit punch and cherry gelatin.
  • Drink the "colon prep" liquid as your doctor tells you. You will want to stay home, because the liquid will make you go to the washroom a lot. Your stools will be loose and watery. It is very important to drink all of the liquid. If you have problems drinking it, call your doctor as they may give you further instructions.
  • Do not eat any solid foods after you drink the colon prep.

What happens on the day of the procedure?

  • Follow the instructions exactly about when to stop eating and drinking. If you don't, your procedure may be cancelled. If your doctor told you to take your medicines on the day of the procedure, take them with only a sip of water.
  • Do not apply lotions, perfumes, deodorants, or nail polish.
  • Take off all jewellery and piercings. And take out contact lenses, if you wear them.

At the clinic or hospital

  • Bring a picture ID.
  • You may choose if you want to have sedation medicine to help you relax. Many people choose to have sedation to be more comfortable. You will be kept comfortable and safe by the doctor or nurse who gives you the sedation medicine. The sedation may make you feel sleepy or light headed.
  • You will lie on your back or your side with your knees drawn up toward your belly. The doctor will gently put a gloved finger into your anus. Then the doctor puts the scope in and moves it into your colon. The scope goes in easily because it is lubricated.
  • You may have cramps when air is put into the colon to help the doctor see. Try to breathe deeply and slowly through your mouth to relax your belly muscles. You may feel and hear air escape around the scope. There is no need to be embarrassed about it. The passing of air is expected.
  • The doctor may also use small tools to take tissue samples for a biopsy or to remove polyps. This does not hurt.
  • The test usually takes 30 to 45 minutes. But it may take longer. It depends on what is found and what is done.

When should you call your doctor?

  • You have questions or concerns.
  • You don't understand how to prepare for your procedure.
  • You are having trouble with the bowel prep.
  • You become ill before the procedure (such as fever, flu, or a cold).
  • You need to reschedule or have changed your mind about having the procedure.

When should you call for help after your procedure?

Call 911 anytime you think you may need emergency care. For example, call if:
  • You passed out (lost consciousness) or feel like you will faint.
  • You pass a lot of blood from your rectum.
  • You have trouble breathing.
Call your doctor, nurse call line, or seek immediate medical care if:
  • You have pain that does not get better even after passing gas.
  • You are sick to your stomach or cannot drink fluids.
  • You have new or worse belly pain.
  • You have blood in your stools.
  • You have a fever (over 38°C or 100.4°F).
  • You cannot pass stools or gas.
Watch closely for changes in your health, and contact your doctor or nurse call line (811 in Alberta) if you have any problems or questions.

Where can you learn more?

Go to

Enter C315 in the search box to learn more about "Colonoscopy: Before Your Procedure".

Adapted with permission from copyrighted materials from Healthwise, Incorporated (Healthwise). This information does not replace the advice of a doctor. Healthwise disclaims any warranty and is not responsible or liable for your use of this information. Your use of this information means that you agree to the Terms of Use. How this information was developed to help you make better health decisions.