What is a Fecal Occult Blood Test (FOBT) and when is it used?
What Is a Fecal Occult Blood Test (FOBT)?
A Fecal Occult Blood Test (FOBT) is a non-invasive screening test used to detect hidden (occult) blood in a person’s stool. “Occult” means not visible to the naked eye — the test identifies microscopic amounts of blood that cannot be seen but may indicate a problem in the gastrointestinal tract, including the possibility of colorectal cancer or precancerous polyps.
FOBT is one of several approved methods for colorectal cancer screening and is particularly valuable as an option for patients who cannot or do not wish to undergo colonoscopy.
How Does an FOBT Work?
There are two main types of fecal occult blood testing:
- Guaiac-based FOBT (gFOBT): The traditional method. A stool sample is applied to a special card treated with a chemical (guaiac). A developer solution is then applied, and the test is positive if a color change occurs, indicating the presence of blood. Patients must avoid certain foods (red meat, some vegetables) and medications before the test to reduce false positives.
- Fecal Immunochemical Test (FIT): A newer and generally preferred method that uses antibodies to detect human blood proteins specifically. FIT does not require dietary restrictions and is considered more specific than the guaiac method.
FOBT requires stool samples to be collected at home and mailed or brought to a lab. Annual testing is recommended for those using FOBT as their primary colorectal cancer screening method.
What Can Cause a Positive FOBT?
A positive FOBT — meaning blood was detected in the stool — does not automatically mean cancer is present. Blood in the stool can result from a variety of causes, including hemorrhoids, inflammatory bowel disease, diverticulosis, stomach ulcers, and benign polyps. However, a positive result must always be followed up with a colonoscopy to identify the source of bleeding and rule out colorectal cancer or precancerous lesions.
Failure to Follow Up on a Positive FOBT and Medical Malpractice
One of the most critical points about FOBT is what happens after a positive result. A healthcare provider who receives a positive FOBT result has an obligation to ensure the patient receives follow-up evaluation — typically a colonoscopy. Failure to follow up on a positive result, or failure to communicate a positive result to the patient, can delay the diagnosis of colorectal cancer and allow the disease to advance to a less treatable stage.
In Pennsylvania, a physician’s failure to properly act on an abnormal screening result — including a positive FOBT — can form the basis of a medical malpractice claim for delayed cancer diagnosis if the patient is ultimately diagnosed with colorectal cancer at an advanced stage. An experienced Pennsylvania medical malpractice attorney can evaluate whether the standard of care was met and advise you on your options.
