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Understanding the Various Screening Options for Colorectal Cancer

Understanding the Various Screening Options for Colorectal Cancer

Nearly 160,000 new cases of colorectal cancer are diagnosed each year, according to the American Cancer Society. Fortunately, those numbers have been declining, thanks to the increased use of colorectal cancer screening tests.

Today, there are multiple screening options, and understanding those options can help you select the correct method. In this post, the Desert West Surgery team offers a brief overview of colorectal cancer screening tests to help you make the best choice.

Stool tests

Stool tests use a sample of your stool or feces to look for changes that could indicate cancer or precancer. 

Fecal occult blood test (FOBT)

In medical terminology, occult means hidden, and that’s what this test does — look for blood that’s hidden in your stool sample. Bleeding can be a symptom of colorectal cancer, but it’s rarely visible or detectable without a special test.

For the FOBT, a chemical (guaiac) is added to the sample. If blood is present, a lab technician can evaluate a chemical reaction.

This type of test can be performed at home using a special kit. The kit contains a tool to collect a stool sample and containers to return the sample to your doctor or a lab.

Fecal immunochemical test (FIT)

FIT works similarly to the fecal occult test, but instead of using a chemical, it uses antibodies to detect the presence of blood in a small stool sample you collect at home. The FIT and FOBT are performed once a year, and if blood is detected in either test, you’ll need a colonoscopy to determine the source.

Stool DNA test

Like FIT and FOBT, this test looks for occult blood hidden in your stool. But it also goes one step further and evaluates the sample for the presence of tiny fragments of abnormal DNA. These fragments are shed from cancer cells or polyps, and if found in your stool sample, it could indicate cancer or precancer.

You should have this test every three years. As with FOBT and FIT, you'll need a colonoscopy to follow up if the test detects blood or abnormal DNA (or both).

Visual tests

Visual tests use a special scope or computed tomography to examine your colon and look for polyps or other areas of abnormal tissue.


Considered by many to be the gold standard for colorectal cancer screening, a colonoscopy uses a long, thin, flexible tube called a colonoscopy to examine your entire colon, as well as your rectum. The tube is equipped with a bright light and a video camera.

Before a colonoscopy, you'll undergo a special "prep" to empty your bowels. You'll also have a brief period of fasting. Following prep instructions is critical for obtaining accurate results.

A colonoscopy is performed under sedation, so you'll nap throughout the procedure. At the start of the procedure, your doctor inflates your colon with inert gas to make it easier to visualize the colon lining. 

The scope is also equipped with special instruments to remove polyps and take tissue samples as needed so they can be evaluated in a lab. Colonoscopy should be performed every ten years or more frequently for people with risk factors for colorectal cancer.

Flexible sigmoidoscopy

This test is similar to a colonoscopy, but it only examines the lower part of your colon (sigmoid colon) and rectum. Because of this limitation, flexible sigmoidoscopy is not routinely used as a screening tool for colorectal cancer.

Virtual colonoscopy

Also called a CT (computed tomography) colonoscopy, a virtual colonoscopy uses a series of X-ray images to produce detailed images of your colon and rectum. A computer splices these images together to make a complete image of your rectum and colon that your doctor can analyze.

For this test, you lie on a table that slides into the CT scanner. Before your test, your doctor inserts a tube into your rectum and inflates your colon with gas, making obtaining clear images of your colon easier. You may also need to drink a special liquid. 

The entire test takes about 10 minutes and should be performed every five years for people at average risk of colorectal cancer. 

Schedule your screening test today

Colorectal cancer screening is quick and essential for staying healthy. Call Desert West Surgery or visit one of our Las Vegas, Nevada, locations today to schedule your screening test.

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