A stool analysis
is a series of tests done on a stool (feces) sample to help diagnose certain
conditions affecting the
digestive tract . These conditions can include
infection (such as from
bacteria), poor nutrient absorption, or cancer.
For a stool analysis, a stool sample is collected in a clean
container and then sent to the laboratory. Laboratory analysis includes
microscopic examination, chemical tests, and microbiologic tests. The stool
will be checked for color, consistency, amount, shape, odor, and the
presence of mucus. The stool may be examined for hidden (occult) blood, fat,
white blood cells , and sugars called reducing
pH of the stool also may be measured. A stool
culture is done to find out if bacteria may be causing
Why It Is Done
Stool analysis is done to:
- Help identify diseases of the digestive tract,
liver , and
pancreas . Certain
enzymes (such as trypsin or elastase) may be evaluated
in the stool to help determine how well the pancreas is functioning.
- Help find the cause of symptoms affecting the digestive tract,
including prolonged diarrhea, bloody diarrhea, an increased amount of gas,
nausea, vomiting, loss of appetite, bloating, abdominal pain and cramping, and
- Screen for
colon cancer by checking for hidden (occult)
- Look for parasites, such as
- Look for the cause of an infection, such as
fungus, or a virus.
- Check for poor
absorption of nutrients by the digestive tract (malabsorption syndrome). For
this test, all stool is collected over a 72-hour period and then checked for
fat (and sometimes for meat fibers). This test is called a 72-hour stool collection or
quantitative fecal fat test.
Talk to your doctor about any concerns you have regarding
the need for the test, its risks, how it will be done, or what the results will
mean. To help you understand the importance of this test, fill out the
medical test information form(What is a PDF document?).
How To Prepare
Many medicines can change the results
of this test. You will need to avoid certain medicines depending on which
kind of stool analysis you have. You may need to stop taking medicines such as
antacids, antidiarrheal medicines, antiparasite medicines, antibiotics,
nonsteroidal anti-inflammatory drugs (NSAIDs) for 1 to
2 weeks before you have the test. Be sure to tell your doctor about all the
nonprescription and prescription medicines you take.