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Updated: Nov 18, 2023

Dr. Ken D. Nguyen is the president and co-founder of Pacifica Digestive Health. His clinical interests include screening and management of gastric cancer in Asian patients, viral hepatitis (including hepatitis B and hepatitis C), advanced liver disease and cirrhosis, colon cancer screening, and international medicine.


Pacifica Digestive Health Patient Education - Colonoscopy

What is a Colonoscopy?

A colonoscopy is the examination of the large intestine and the distal part of the small intestine using a camera on a flexible tube inserted from the anus performed endoscopically. Easily put, it is the inspection of the colon carried out by a gastroenterologist. The flexible tube used is known as a colonoscope. A colonoscopy can easily provide a visual diagnosis of a condition in the gastrointestinal (GI) tract, for example, the presence of ulcerations or polyps and allows for the removal or biopsy of suspected cancerous lesions. Once removed, the polyps can be studied and it can be determined whether they are precancerous or not. Polyps are small mushroom-like growths on the inside wall of the colon or rectum. They can take up to 15 years to become cancerous, while others remain benign.

What Are Some Reasons to Perform a Colonoscopy?

A colonoscopy is a safe, painless and easy way to identify problems in the GI tract such as:

  • Persistent belly pain

  • Persistent rectal pain

  • Stool containing blood

  • Persistent changes in stool such as diarrhea

  • Identification of an inflamed colon or other abnormalities seen on a computerized tomography (CT) scan

  • To screen for colon cancer

How to Prepare for a Colonoscopy?

Before a colonoscopy is performed, your doctor or nurse will review the steps you need to get ready for the examination. This includes:

  • Disclosing all the medications you are currently taking and any allergies you may have. If you are currently on medication, your doctor will advise you on whether you should stop taking them just before the procedure or not.

  • Informing your doctor of any pre-existing conditions. If you have any conditions such as diabetes or Deep Vein Thrombosis which require you to take medication regularly, you will have to inform your doctor. Other health problems such as heart or lung issues should be disclosed. Also, if you have had a stomach or bowel surgery or other GI problems, this may interfere with the procedure if not disclosed early.

  • Clean out your colon before the procedure. There are several methods you can use to clean out your colon. Most times. You will need to only consume clear liquids before the procedure or go on a water only fast for a specified number of hours. You may also be asked to drink a liquid that will move your bowels until your stool comes out clear. You may also be asked to clear your bowels using different diets or the use of enemas or suppositories. Whatever the case, be sure to clearly follow the doctor’s guidelines.

  • Plan to have someone with you during the procedure as you will be given pain blockers which cause drowsiness thus you will not be able to drive home after the procedure.

What Should I Expect During an Colonoscopy?

A colonoscopy can be done as an outpatient procedure, allowing you to go home right after the procedure. After ensuring that you have followed the dietary guidelines before the procedure and that you have filled out the consent form, you are ready for the procedure. Here is what you should expect during the procedure:

  • An intravenous line (IV) will be started to give you fluids and medication to block the pain.

  • Once you are relaxed, the doctor will perform a rectal exam using his finger which will be gloved and lubricated.

  • Using the colonoscopy, air will be passed to expand your bowels for better viewing.

  • The doctor may need to do a biopsy on a small tissue sample. If he finds a polyp, he will remove it using the tools on the endoscope (this may take more time).

  • Sometimes the doctor will encounter certain parts of your colon that are difficult to pass through. To overcome this, the procedure staffs may push on your belly to help the endoscope to pass through or you may be asked to change position.

  • Finally, the doctor will remove the endoscope and you will wake up after the drugs wear off.

What Are the Risks and Complications of a Colonoscopy?

A colonoscopy is a very straight-forward and common procedure with little complications. Very rarely complications may occur, which may include bleeding and perforation (or having a hole in the digestive tract). If any complications were to occur, most can be easily managed or fixed by the doctor.

What Should I Expect After a Colonoscopy?

After the procedure, a doctor or nurse will review the results of the endoscopy with you and give you recommendations for the next steps. You may feel some minor issues such as a mild bloating, gas, or mild cramps immediately after the test because of the air that was used. Passing gas immediately after the procedure will make these symptoms better. These issues should clear completely after 24 hours. Your doctor will let you know what and when you can eat and drink. You also cannot drive after your procedure because of the sedation you received. You should plan to resume your normal activities 24 hours after your exam. If you were on any blood thinners prior to your procedure and they were held, you will be provided with instructions on when to resume them. If a biopsy was carried out, you will be informed by your doctor or his/her office by phone or with a letter in the mail explaining the results and recommended next steps.

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