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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
Stool analysis is done to:
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?).
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.
Be sure to
tell your doctor if you have:
If your stool is being tested for blood, you may need to avoid certain foods for 2 to 3 days before the test. This depends on what kind of stool test you use. And do not do the test during your menstrual period or if you have active bleeding from hemorrhoids. If you aren't sure about how to prepare, ask your doctor.
Do not use a stool sample for testing that has been in contact with toilet bowl cleaning products that turn the water blue.
Stool samples can be collected at home,
in your doctor's office, at a medical clinic, or at the hospital. If you
collect the samples at home, you will be given stool collection kits to use
each day. Each kit contains applicator sticks and two sterile
You may need to collect more than one sample over 1 to
3 days. Follow the same procedure for each day.
samples as follows:
Take the sealed container to your doctor's office or the
laboratory as soon as possible. You may need to deliver your sample to the lab
within a certain time. Tell your doctor if you think you may have trouble
getting the sample to the lab on time.
If the stool is collected
in your doctor's office or the hospital, you will pass the stool in a plastic
container that is inserted under the toilet seat or in a bedpan. A health
professional will package the sample for laboratory analysis.
will need to collect stool for 3 days in a row if the sample is being tested
for quantitative fats. You will begin collecting stool on the morning of the
first day. The samples are placed in a large container and then
You may need to collect several stool samples over 7
to 10 days if you have digestive symptoms after traveling outside the
Samples from babies and young children may be collected
from diapers (if the stool is not contaminated with urine) or from a
small-diameter glass tube inserted into the baby's rectum while the baby is
held on an adult's lap.
Sometimes a stool sample is collected
using a rectal swab that contains a preservative. The swab is inserted into the
rectum, rotated gently, and then withdrawn. It is placed in a clean, dry
container and sent to the lab right away.
There is no pain while collecting a stool
sample. If you are constipated, straining to pass stool may be painful.
If your health professional uses a rectal swab to collect the sample, you
may feel some pressure or discomfort as the swab is inserted into your
Any stool sample may contain germs that can
spread disease. It is important to carefully
wash your hands and use careful handling techniques to avoid spreading
A stool analysis is a series of tests
done on a stool (feces) sample to help diagnose certain conditions affecting
the digestive tract.
The normal values listed here—called a reference range—are just a guide. These ranges vary from lab to lab, and your lab may have a different range for what's normal. Your lab report should contain the range your lab uses. Also, your doctor will evaluate your results based on your health and other factors. This means that a value that falls outside the normal values listed here may still be normal for you or your lab.
Stool analysis test
results usually take at least 1 to 3 days.
The stool appears brown, soft, and
well-formed in consistency.
The stool does not contain blood, mucus,
pus, undigested meat fibers, harmful
The stool is shaped like a tube.
pH of the stool is 7.0–7.5.1
The stool contains less than 0.25 grams per deciliter (g/dL)[less than 13.9 millimoles per liter (mmol/L)] of sugars called reducing
The stool contains 2–7 grams of fat per 24 hours (g/24h).1
The stool is black, red, white, yellow, or
The stool is liquid or very
There is too much stool.
The stool contains blood, mucus, pus,
undigested meat fibers, harmful bacteria, viruses, fungi, or parasites.
The stool contains low levels of
enzymes, such as trypsin or elastase.
The pH of the stool is less than 7.0 or
greater than 7.5.
The stool contains 0.25 g/dL
(13.9 mmol/L) or more of
sugars called reducing factors.
The stool contains more than 7 g/24h of fat (if
your fat intake is about 100 g a day).
Many conditions can change the results
of a stool analysis. Your doctor will talk with you about any abnormal results
that may be related to your symptoms and past health.
Reasons you may not be able to
have the test or why the results may not be helpful include:
CitationsFischbach FT, Dunning MB III, eds. (2009).
Manual of Laboratory and Diagnostic Tests, 8th ed.
Philadelphia: Lippincott Williams and Wilkins.Other Works ConsultedChernecky CC, Berger BJ (2008). Laboratory Tests and Diagnostic Procedures, 5th ed. St. Louis:
Saunders.Fischbach FT, Dunning MB III, eds. (2009).
Manual of Laboratory and Diagnostic Tests, 8th ed.
Philadelphia: Lippincott Williams and Wilkins.Pagana KD, Pagana TJ (2010). Mosby’s Manual of Diagnostic and Laboratory Tests, 4th ed. St. Louis: Mosby Elsevier.
March 7, 2012
Adam Husney, MD - Family Medicine & Jerome B. Simon, MD, FRCPC, FACP - Gastroenterology
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