Patient education: Stool DNA test (The Basics)

What is a stool DNA test? — 

This is a type of lab test done on a stool sample. "Stool" is another word for bowel movements.

The test looks for:

●Changes in your DNA – All your body's cells contain DNA. Your colon "sheds" cells that get into your stool when you have a bowel movement. Certain changes in your DNA can be a sign of cancer or "pre-cancer."

●Blood in your stool – The test can find even tiny amounts of blood that cannot be seen.

For a stool DNA test, you collect an entire bowel movement and send it to a lab for testing.

Why might I get a stool DNA test? — 

The main reason is to "screen" for colon and rectal cancer.

Screening is a way doctors check the colon and rectum for signs of cancer or "polyps." Polyps are growths that might become cancer.

When a stool DNA test is used for cancer screening in the US, it is usually repeated every 1 to 3 years.

How do I prepare for a stool DNA test? — 

You should not need to do anything special to prepare.

Your doctor will send a prescription to the company that does the stool DNA test. Or they might give you the prescription so you can send it yourself. Then, the company will mail a kit to your home. The kit will include supplies and instructions for collecting a bowel movement at home.

Ask your doctor or nurse if you have any questions about how to get the test kit.

How do I collect a stool sample? — 

The test kit will come with specific instructions. Read and follow the instructions carefully.

In general, these are the steps:

●Prepare your kit when you are ready to have a bowel movement.

●Follow the instructions to attach the container to the toilet. This will catch your stool.

●Have a bowel movement as usual. The entire bowel movement should go into the container.

●Add the liquid from the kit to the container with your stool inside. Cover the container.

●For some tests, you also take a small sample of stool to put in a second container.

●Put the container or containers into the box that comes in the kit. Make sure your name and any other required information is on the container.

●Wash your hands.

●Follow the instructions for sending your sample or samples to the lab.

How will I get my results? — 

The lab will send you the results of your test when they are ready. The lab might also send a copy of the results to your doctor or nurse. If you use an online "patient portal," you might get an alert there when your results are ready.

The lab should tell you when to expect your results. If you do not get the results within 3 to 4 weeks, contact your doctor or nurse or the lab that performed the test.

What do my results mean? — 

The result can be:

●Negative – This means the test did not find certain DNA changes or blood in your stool.

●Positive – This means the test did find certain DNA changes or blood in your stool. Your doctor or nurse will talk to you about what to do next. In most cases, they will want to do another test called a "colonoscopy" to check for colon polyps or cancer. For a colonoscopy, a doctor puts a thin tube into your anus. Then, they gently move the tube up into your rectum and colon to check for polyps or signs of cancer.

If you do have a health problem, your doctor will work with you to come up with a treatment plan.

More on this topic

Patient education: Stool collection for testing (The Basics)
Patient education: Colon and rectal cancer screening (The Basics)
Patient education: Colon and rectal cancer (The Basics)
Patient education: Colon polyps (The Basics)
Patient education: Colonoscopy (The Basics)

Patient education: Screening for colorectal cancer (Beyond the Basics)
Patient education: Colon and rectal cancer (Beyond the Basics)
Patient education: Colon polyps (Beyond the Basics)
Patient education: Colonoscopy (Beyond the Basics)