What is Colonoscopy Test: Types, Preparation & More | Gleneagles Global Health City, Chennai

What is Colonoscopy Test?


Colonoscopy is a medical test used to examine the large intestine (colon and rectum) using a colonoscope. It can detect issues like ulcers, polyps (abnormal tissue growth on a mucous membrane), and colorectal cancer.

What is Colonoscopy?

In this procedure, your healthcare provider will look at the inside of the colon and rectum using a device called colonoscope. A colonoscope is a very thin, long, flexible tube attached with a small video camera and light at the end. The video camera provides a total inside view of the rectum and colon. It is inserted through the anus that goes into the rectum and colon.

The camera at the end aids to identify anything suspicious in these areas of the large intestine. Sometimes, these colonoscopes are attached with instruments that can help in taking a tissue sample of the suspicious area (biopsy), that is used to further examine it under a microscope.

Suspicious areas that could be found are ulcers, polyps or cancer. Polyps are small growths and are non-cancerous. However, they have the potential to turn into cancer. This test is also suggested to look for the cause of any bothersome bowel problems or worrisome symptoms.

It is to be noted that, colonoscopy is different from virtual colonoscopy.

Difference between Colonoscopy and Virtual Colonoscopy

Colonoscopy is the traditional method of detection of suspicious areas inside the rectum and colon, that requires insertion of a scope through the rectum. Contrary to this, a virtual colonoscopy uses CT scans to create hundreds of cross-sectional images of abdominal organs.

Virtual colonoscopy is less invasive, does not require the use of anesthesia and is less time consuming, healthcare providers suggest this procedure for patients who may not be suitable candidates for the conventional colonoscopy. Example of such patients includes: patients who are currently on blood thinning medications.

Why is Colonoscopy done?

It is done for various reasons. Your healthcare provider might order for one or more of the following reasons:

  • To find the cause of the intestinal symptoms, such as abdominal pain, rectal bleeding (bleeding from your anus), changes in bowel activity (diarrhea/constipation), sudden weight loss
  • As a screening tool: If you are 45 years or older, then you may be at an average risk of getting colon cancer. Or if you have no colon cancer risk factors other than old age, your doctor might recommend this test for every 10 years, just to be sure.
  • To look for more polyps: If you had a history of polyps, your healthcare provider will recommend a follow-up to look for any polyps that might have developed.
  • For treatment purposes: Sometimes, a colonoscopy is performed to treat an issue, such as placing a stent or removing an object in your colon region.

What Happens During a Colonoscopy Test

Average duration is about: 30 to 60 minutes.

The following steps describe your colonoscopy procedure:

  • The procedure begins with you taken in to a private room and you will be asked to lie down on your side. A sheet will be draped over your body.
  • A nurse or anesthesia specialist will give you a pain medication and a sedative intravenously (through a needle into the vein).
  • At the beginning of a colonoscopy, your healthcare will blow air into your colon through a small tube. This inflates and enlarges the colon that enables the healthcare provider to get better.
  • You might be asked to change your position occasionally during the test, for a better view during the test. A nurse will help you when you fall asleep.
  • In case you have an abnormal growth, or polyp, the healthcare provider will remove it. Or, they may take a small sample of the tissue for further examination.
  • Overall, the procedure is not painful, and the healthcare provider will stop any bleeding at the moment.

In rare cases, the tube used for a colonoscopy might puncture the colon. When this happens, your healthcare provider will repair it with a surgery.

How to Prepare for Colonoscopy

Before the procedure

You should inform your doctor about any health conditions you have and the medicines you take, this includes prescribed and over-the-counter medicines, even the vitamins and any health supplements you take.

Because this procedure involves a part of the digestive system, you may be asked to change diet and follow a clear liquid diet for about 1 to 3 days to keep your gut clear. Your healthcare provider will give you the necessary instructions for the type the food to intake and what to avoid.

After the Procedure

After the procedure, you will be watched closely to make sure you do not have any complications and to treat to them right away in case they arise.

You might have cramps or feel bloated right after the test, as air was pumped into your colon prior to the procedure. This is a common side effect, and it goes away on its own. Sometimes, you might even pass gas or may have diarrhea as you release air from your colon.

You will not be allowed to drive a vehicle, as the procedure involved anesthesia. You might stay at the center where you got the test done or call for a ride home.

Once you are home, if you observe any of the following symptoms, contact your healthcare provider:

  • Severe abdominal pain or discomfort
  • A high fever
  • Dizziness
  • Weakness
  • Continuous bleeding from your rectum (Small amounts of blood is normal, however, if it is continuous – it could be a sign of blood clot.)

Frequently asked questions (FAQs)

What is a diagnostic colonoscopy?

A colonoscopy is considered a "diagnostic" colonoscopy if previous radiological examinations, such as X-rays, CT scans, or MRI scans, have shown abnormalities in your colon or rectum.

What role does colonoscopy play in colorectal cancer screening?

Colonoscopy is considered the gold standard of colorectal cancer screening method because it looks at the entire colon and can detect and remove polyps in the same procedure.

Who should be screened for colon cancer and when?

The American Cancer Society recommends that adults be screened for colon cancer beginning at age 50 – or even earlier if there is a family history of the disease.

Does insurance cover this procedure?

Most insurance providers cover colonoscopy test done in hospital or day care center for colon cancer screening; however, insurance coverage varies. You should check with your health insurance provider to determine your colorectal cancer screening benefits.

Can colonoscopy be done even while menstruating?

Yes, it can be done during menstruation. Tampons can be worn at the patient's request.

Will I receive sedation for a colonoscopy test?

You will receive “conscious sedation” for the exam. This is the common type of sedation used for a colonoscopy. It reduces pain and makes you less aware of things around you. Almost, all patients find this comfortable.

For some who cannot take the drugs used for conscious sedation due to other health conditions, deep sedation is used. This is not a common choice. If you have been given deep sedation, you will not be aware of the colonoscopy taking place.

Dr B Mahadevan
Dr B Mahadevan
M.B.B.S, MD (Paediatrics) - JIPMER, DM (Gastroenterology)
Senior Consultant & Head of Department – Medical Gastroenterology & Therapeutic Endoscopy
Department of Medical Gastroenterology & Endoscopy

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