How to Do a Fecal Occult Blood Test (FOBT)

This information will teach you how to collect stool (poop) samples at home for your fecal occult blood test (FOBT).

About Your FOBT

A FOBT is a lab test used to check your stool for occult blood. Occult blood is blood that you can’t see by looking at your stool. There are many reasons you may have blood in your stool. Your healthcare provider will tell you why you’re having the test.

For your FOBT, you will collect samples of your stool 3 days in a row. This increases the chance of finding blood, since the bleeding may not happen every day. If you don’t have a bowel movement on one of the 3 days, talk with your healthcare provider. They will talk with you about collecting the 3 samples over a longer period of time.

Getting ready for your FOBT

Ask your healthcare provider how many days before the test you should start getting ready. They may give you special instructions. It’s important to follow their instructions and the instructions below to be sure your test results are accurate.

• Starting 3 days before you begin collecting your stool samples, avoid:
  • Red meat, such as beef, lamb, or liver.
  • Raw fruits and vegetables.
  • Vitamin C, such as fruit juices with vitamin C and vitamin C supplements in doses higher than 250 milligrams (mg) per day.
  • Antacids (medications to relieve heartburn or stomach pain, such as Tums®).
  • Medications to stop diarrhea (loose or watery bowel movements).
  • Iron supplements.
  • Your healthcare provider will give you the resource How To Check if a Medicine or Supplement Has Aspirin, Other NSAIDs, Vitamin E, or Fish Oil, which lists common medications that have these products in them. It also lists medications you can take instead.
  • If you take aspirin to prevent a heart attack or stroke, don’t stop taking it unless your healthcare provider tells you to.
  • Menstrual period
  • Bleeding hemorrhoids (swollen veins in your anus)
  • Blood in your urine (pee)

  Collecting the sample

  

  Supplies

  You will need the following supplies:

  • Hemoccult® slide.
  • Applicator stick.
  • A clean, dry container.
  • Trash can.

  Instructions

  1. Gather your supplies. Place them in the bathroom where you can reach them easily.
     • Remove the Hemoccult slide from its paper envelope. Set the envelope aside.
     • Don’t set the Hemoccult slide or applicator stick on the edge of the sink, bath tub, or toilet tank. They shouldn’t get wet.
     • Always keep the Hemoccult slides at room temperature, away from heat and light.
     • Make sure your name, date of birth, and Medical Record Number (MRN) are on the card. If this information isn’t on the card, write it in.
  2. Open the large front flap of the Hemoccult slide. You may notice a light blue discoloration on the paper in the squares above boxes A and B. The discoloration won’t affect the test.
  3. Sit on the toilet like you usually do to have a bowel movement (poop). Use the clean, dry container to catch your stool before it touches the water in the toilet.
  4. Take a sample of your stool with one end of an applicator stick. Apply a thin smear of stool inside the square marked “A” on the Hemoccult slide (see Figure 1).
  5. Use the stick to collect a second sample from a different part of your stool. Apply a thin smear of stool inside the square marked “B”.
  6. Throw out the stick in the trash.
  7. Close the cover of the Hemoccult slide and put it back into its paper envelope. Don’t put it in anything waterproof, such as a plastic bag. Store it at room temperature, away from light, children, and pets.
  8. Empty the container that holds the stool into the toilet. Flush the toilet.
  9. Wash your hands. Wet your hands with warm water and then rub your hands with soap for at least 20 seconds. Rinse your hands.

  Repeat these steps to collect your samples on days 2 and 3. Write the date of collection next to each sample.

  After you collect the samples

  You can store the samples on the Hemoccult slide for 5 to 7 days from the date of your first collection. Don’t mail your stool samples. Your healthcare provider will tell you where to take your stool samples.

  Your results

  Your healthcare provider will call you with your results, explain what they mean, and tell you what to do next.

  If you have questions or concerns, contact your healthcare provider. A member of your care team will answer Monday through Friday from 9 a.m. to 5 p.m. Outside those hours, you can leave a message or talk with another MSK provider. There is always a doctor or nurse on call. If you’re not sure how to reach your healthcare provider, call .

  If you have questions or concerns, contact your healthcare provider. A member of your care team will answer Monday through Friday from 9 a.m. to 5 p.m. Outside those hours, you can leave a message or talk with another MSK provider. There is always a doctor or nurse on call. If you’re not sure how to reach your healthcare provider, call .

  For more resources, visit www.mskcc.org/pe to search our virtual library.

  How to Do a Fecal Occult Blood Test (FOBT) - Last updated on December 26, 2023
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