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Fecal Immunochemical Test for Occult Blood (FIT/OBT)

Published: August 9, 2026Updated: August 16, 2026

This test detects hidden (occult) blood in your stool using a sensitive chemical process to identify potential bleeding sources in the digestive tract.

Quick summary

["Early detection may help find issues like colorectal cancer or other gastrointestinal bleeding."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
74743-6
Short code
Deprecated E faecalis hsp60 Bld Pos Ql Prb Mag
Synonyms
Deprecated E faecalis hsp60 Bld Pos Ql Prb Mag
Category
chemistry
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
probe-mag-capture
Specimen volume
3 mL
Stability
Room temperature: 4h, Refrigerated: 24h
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

Why This Test Is Done

Your doctor may recommend this test as part of a colorectal cancer screening, especially if you're 50 or older, or if you have symptoms like unexplained weight loss, persistent abdominal pain, or changes in bowel habits. It can also be used to monitor conditions like inflammatory bowel disease.

How the Test Works

A small sample of your stool is collected in a provided container. The test detects hemoglobin, a protein in blood, using a chemical reaction that changes color if blood is present. This helps identify hidden blood without needing a full colonoscopy.

Sample Collection

You’ll collect a sample using a provided kit, typically over 3 consecutive days. Avoid foods with hidden blood (like red meat, vitamin C supplements, or certain medications) for 3 days before testing to ensure accurate results.

What to Expect After Testing

If the test is positive, further evaluation (like a colonoscopy) will be needed to determine the cause. A negative result does not rule out all bleeding sources, so follow-up with your doctor is important.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

FIT (Fecal Immunochemical Test)

Frequently asked questions

What does a positive result mean?
A positive result suggests there may be hidden blood in your stool, which could indicate conditions like colorectal cancer, polyps, or other gastrointestinal bleeding. Your doctor will guide next steps, such as additional tests or procedures.
Can diet affect this test?
Yes, certain foods, supplements, and medications (like NSAIDs) can interfere with the test. Follow your healthcare provider’s instructions to avoid these for the recommended period before testing.
How often should this test be repeated?
Screening tests like this are typically done every 1–3 years, depending on your age, risk factors, and doctor’s recommendations. Follow-up may include more frequent testing or additional diagnostic procedures if needed.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy