Colon Screening Vs Colonoscopy

Dr. Tyler Buckley

April 26, 2023


A colon screening is a test that checks for signs of cancer or polyps. Screenings can help prevent some forms of colorectal cancer and reduce deaths from it.

Before you have a colonoscopy, your doctor may recommend a special preparation called a “bowel prep.” This involves drinking large amounts of water and eating a liquid diet. This makes it easier for your doctor to see the inner lining of your colon.


A colonoscopy is a medical test that lets your doctor view the inside of the large intestine (colon). This may help diagnose or treat problems like constipation, blood in the stools or diarrhoea.

The test is done under sedation on an outpatient basis at your doctor’s office or hospital. You are given a laxative or enema to empty your colon before the procedure and air is pumped into it to expand it for better visibility.

You are also given medication to make you sleepy and relaxed. This is a form of sedation that’s safer than general anesthesia.

Your doctor may need to remove a piece of tissue (biopsy) from your lining during the test for further testing in a lab. Polyps and growths detected during the test can be removed and checked to see if they are cancerous or not.

Flexible sigmoidoscopy

A flexible sigmoidoscopy is an exam of the sigmoid colon and the lower part of the large intestine (rectum). It is often used to find the cause of changes in bowel movements.

The doctor inserts a long, flexible, lighted tube called a scope into your anus and then guides it through your rectum into your sigmoid colon. The scope is hollow and can be inflated with air for a better view.

This procedure is done to look for polyps and abnormal-looking tissue that could be cancer or pre-cancerous. If polyps are found, the doctor may remove them or take a tissue sample for further testing.

Patients can be given intravenous (IV) sedation to help them relax for the procedure. They can also be given an anti-gas medication to keep them comfortable as they lie on their side and have a hollow tube inserted into their rectum, the colon and then up through their small intestine.

Stool-based tests

A stool-based test is a quick way to check whether or not your gastrointestinal tract is working properly. It can help determine if you have any health problems, such as a condition that affects your immune system (immune bowel disease), or if you have an overgrowth of bacteria or parasites in your colon.

A doctor may use a flexible telescope inserted into the anus (back passage) to examine your intestines. This can help identify a problem and allow your doctor to take a sample of tissue for analysis.

Your doctor may also use the scope to remove polyps. These are small growths in the colon that can develop into cancer.

Before the colonoscopy, you’ll be asked to drink a liquid preparation and have several episodes of loose stool. This is called a bowel preparation or colon cleanse and is very important to get your intestines clean so that your doctor can clearly see any abnormal areas in your bowel.

CT scan

A CT scan is an X-ray exam that uses a computer to create detailed images of the inside of your body. It can show your bones, soft tissues and blood vessels better than a normal X-ray, giving your doctor more information about what is happening in your body.

The test starts by having you lie on an exam table, usually lying on your back. The technologist will use a special machine called a CT scanner to take X-rays of your body.

After you are positioned, the technician will put a thin tube about 2 inches into your rectum and pump air or room air through it to inflate your colon so the CT scanner can get a better view of the interior. This may make you feel bloated or cramps, but most patients don’t have any pain from the procedure.

During the test, the doctor may also collect tiny samples of your intestinal lining or remove growths on your intestines (polyps) for testing. Your results will be sent to your doctor after the test, who will then order more tests if necessary.