A stool test may also be referred to as a “stool sample,” a “stool culture” or “fecal sample. A stool test is used to detect the presence of blood or other gastrointestinal abnormalities, such as colon or gastric cancer, inflammatory bowel disease, hemorrhoids, anal fissures, or infections. This type of test looks at fecal matter for evidence of a medical condition presence or absence of a medical condition, Microbial analysis, microscopy, and chemicals. The test may look for evidence of infection, allergy, blood, or digestive problems. Some stool tests are not cultures.
Another name
Urethral discharge – Gram stain; Feces – Gram stain; Stool – Gram stain; Joint fluid – Gram stain; Pericardial fluid – Gram stain; Gram stain of urethral discharge; Gram stain of the cervix; Pleural fluid – Gram stain; Sputum – Gram stain; Skin lesion – Gram stain; Gram stain of skin lesion; Gram stain of tissue biopsy
A Gram stain is a test used to identify bacteria. It is one of the most common ways to quickly diagnose bacterial infection in the body.
How the Test is Performed
How the test is performed depends on what tissue or fluid from your body is being tested. The test may be quite simple, or you may need to prepare ahead of time.
- You may need to provide a sputum, urine, or stool sample.
- Your health care provider may use a needle to take fluid from your body to test. This could be from a joint, from the sac around your heart, or from the space around your lungs.
- Your provider may need to take a tissue sample, such as from your cervix or skin.
The sample is sent to a laboratory.
- A small amount is spread in a very thin layer on a glass slide. This is called a smear.
- A series of stains are added to the sample.
- A lab team member examines the stained smear under the microscope, looking for bacteria.
- The color, size, and shape of the cells help identify the specific type of bacteria.
How to Prepare for the Test
Your provider will tell you what to do to prepare for the test. For some types of tests, you will not need to do anything.
How the Test will Feel
How the test will feel depends on the method used to take a sample. You may not feel anything, or you may feel pressure and mild pain, such as during a biopsy. You may be given some form of pain medicine so you have little or no pain.
Why the Test is Performed
You may have this test to diagnose an infection caused by bacteria. It can also identify the type of bacteria causing the infection.
This test can help find the cause of various health problems, including:
- Intestinal infection or illness
- Sexually transmitted diseases (STDs)
- Unexplained swelling or joint pain
- Signs of a heart infection or fluid buildup in the thin sac that surrounds the heart (pericardium)
- Signs of infection of the space around the lungs (pleural space)
- Cough that will not go away, or if you are coughing up material with a foul odor or odd color
- Infected skin sore
A normal result means that no bacteria or only “friendly” bacteria were found. Some types of bacteria normally live in certain areas of the body, such as the intestines. Bacteria normally don’t live in other areas, such as the brain or spinal fluid.
Talk to your provider about the meaning of your specific test results.
What Abnormal Results Mean
Abnormal results may indicate an infection. You will need further tests, such as a culture, to find out more about the infection.
Risks
Your risks depend on the method used to remove tissue or fluid from your body. You may have no risk at all. Other risks are rare, but may include:
- Infection
- Bleeding
- Heart or lung puncture
- Collapsed lung
- Breathing problems
- Scarring
Trypsin and chymotrypsin in stool
Stool – trypsin and chymotrypsinTrypsin and chymotrypsin are substances released from the pancreas during normal digestion. When the pancreas does not produce enough trypsin and chymotrypsin, smaller-than-normal amounts can be seen in a stool sample.
This article discusses the test to measure trypsin and chymotrypsin in stool.
How the Test is Performed
There are many ways to collect the samples. Your health care provider will tell you how to collect the stool.
You can catch the stool on plastic wrap that is loosely placed over the toilet bowl and held in place by the toilet seat. Then put the sample in a clean container. One type of test kit contains a special tissue that you use to collect the sample. Then you put the sample in a clean container.
To collect a sample from infants and young children:
- If the child wears a diaper, line the diaper with plastic wrap.
- Place the plastic wrap so that urine and stool do not mix.
A drop of stool is placed on a thin layer of gelatin. If trypsin or chymotrypsin are present, the gelatin will clear.
How to Prepare for the Test
Your health care provider will provide you with the supplies needed to collect the stool.
Why the Test is Performed
These tests are simple ways of finding out whether you have a decrease in pancreas function. This is most often due to chronic pancreatitis.
These tests are most often done in young children who are thought to have cystic fibrosis.
Note: This test is used as a screening tool for cystic fibrosis but it does not diagnose cystic fibrosis. Other tests are needed to confirm a diagnosis of cystic fibrosis.
Normal Results
The result is normal if there is a normal amount of trypsin or chymotrypsin in the stool.
What Abnormal Results Mean
An abnormal result means the trypsin or chymotrypsin levels in your stool are below the normal range. This may mean that your pancreas is not working properly. Other tests may be done to confirm that there is a problem with your pancreas.
Stool C difficile toxin
Antibiotic associated colitis – toxin; Colitis – toxin; Pseudomembranous – toxin; Necrotizing colitis – toxin; C difficile – toxin
The stool C difficile toxin test detects harmful substances produced by the bacterium Clostridium difficile ( C difficile) . This infection is a common cause of diarrhea after antibiotic use.
How the Test is Performed
A stool sample is needed. It is sent to a lab to be analyzed. There are several ways to detect C difficile toxin in the stool sample.
Enzyme immunoassay ( EIA ) is most often used to detect substances produced by the bacteria. This test is faster than older tests, and simpler to perform. The results are ready in a few hours. However, it is slightly less sensitive than earlier methods. Several stool samples may be needed to get an accurate result.
A newer method is to use PCR to detect the toxin genes. This is the most sensitive and specific test. Results are ready within 1 hour. Only one stool sample is needed.
How to Prepare for the Test
There are many ways to collect the samples.
- You can catch the stool on plastic wrap that is loosely placed over the toilet bowl and held in place by the toilet seat. Then you put the sample in a clean container.
- A test kit is available that supplies a special toilet tissue that you use to collect the sample. After collecting the sample, you put it in a container.
Do not mix urine, water, or toilet tissue with the sample.
For children wearing diapers:
- Line the diaper with plastic wrap.
- Position the plastic wrap so that it will prevent urine and stool from mixing. This will provide a better sample.
Why the Test is Performed
You may have this test if your health care provider thinks that diarrhea is caused by the antibiotic medicines you have taken recently. Antibiotics change the balance of bacteria in the colon. This sometimes leads to too much growth of C difficile .
Diarrhea caused by C difficile after antibiotic use often occurs in people who are in the hospital. It also can occur in people who have not recently taken antibiotics. This condition is called pseudomembranous colitis .
Normal Results
No C difficile toxin is detected.
Note: Normal value ranges may vary slightly among different laboratories. Talk to your provider about the meaning of your specific test results.
What Abnormal Results Mean
Abnormal results mean that toxins produced by C difficile are seen in the stool and are causing diarrhea.
Risks
There are no risks associated with testing for C difficile toxin.
Considerations
Several stool samples may be needed to detect the condition. This is especially true if the older EIA for toxin test is used.
Fecal culture
Stool culture; Culture – stool; Gastroenteritis fecal culture
A fecal culture is a lab test to find organisms in the stool (feces) that can cause gastrointestinal symptoms and disease.
How the Test is Performed
A stool sample is needed.
There are many ways to collect the sample.
You can collect the sample:
- On plastic wrap. Place the wrap loosely over the toilet bowl so that it is held in place by the toilet seat. Put the sample in a clean container given to you by your health care provider.
- In a test kit that supplies a special toilet tissue. Put it in a clean container given to you by your provider.
Do not mix urine, water, or toilet tissue with the sample.
For children wearing diapers:
- Line the diaper with plastic wrap.
- Position the plastic wrap so that it will prevent urine and stool from mixing. This will provide a better sample.
Return the sample to the laboratory as soon as possible. Do not include toilet paper or urine in the specimen.
In the lab, a technician places a sample of the specimen in a special dish. The dish is then filled with a gel that boosts the growth of bacteria or other germs. If there is growth, the germs are identified. The lab technician may also do more tests to determine the best treatment.
How to Prepare for the Test
You will get a collection container for the stool specimen.
How the Test will Feel
There is no discomfort.
Why the Test is Performed
The test is performed when your health care provider suspects that you may have a gastrointestinal infection. It may be done if you have severe diarrhea that does not go away or that keeps coming back.
Normal Results
There are no abnormal bacteria or other organisms in the sample.
Talk to your provider about the meaning of your specific test results.
What Abnormal Results Mean
Abnormal results may mean you have an intestinal infection .
Risks
There are no risks.
Considerations
Often other stool tests are done in addition to the culture, such as:
- Gram stain of stool
- Fecal smear
- Stool ova and parasites exam
Stool guaiac test
gFOBT; Guaiac smear test; Fecal occult blood test – guaiac smear; Stool occult blood test – guaiac smear
The stool guaiac test looks for hidden (occult) blood in a stool sample. It can find blood even if you cannot see it yourself. It is the most common type of fecal occult blood test (FOBT).
Guaiac is a substance from a plant that is used to coat the FOBT test cards.
How the Test is Performed
Usually, you collect a small sample of stool at home. Sometimes, a doctor may collect a small amount of stool from you during a rectal examination.
If the test is done at home, you use a test kit. Follow the kit instructions exactly. This ensures accurate results. In brief:
- You collect a stool sample from 3 different bowel movements.
- For each bowel movement, you smear a small amount of the stool on a card provided in the kit.
- You mail the card to a laboratory for testing.
DO NOT take stool samples from the toilet bowl water. This can cause errors.
For infants and young children wearing diapers, you can line the diaper with plastic wrap. Place the plastic wrap so that it keeps the stool away from any urine. Mixing of urine and stool can spoil the sample.
How to Prepare for the Test
Some foods can affect test results. Follow instructions about not eating certain foods before the test. These may include:
- Red meat
- Cantaloupe
- Uncooked broccoli
- Turnip
- Radish
- Horseradish
Some medicines may interfere with the test. These include vitamin C, aspirin, and nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen and naproxen. Ask your health care provider if you need to stop taking these before the test. Never stop or change your medicine without first talking to your provider.
How the Test will Feel
The at-home test involves a normal bowel movement. There is no discomfort.
You may have some discomfort if the stool is collected during a rectal exam.
Why the Test is Performed
This test detects blood in the digestive tract. It may be done if:
- You are being screened or tested for colon cancer
- You have abdominal pain, changes in bowel movements, or weight loss
- You have anemia (low blood count)
- You say you have blood in the stool or black, tarry stools
Normal Results
A negative test result means that there is no blood in the stool.
What Abnormal Results Mean
Abnormal results may be due to problems that cause bleeding in the stomach or intestinal tract, including:
- Colon cancer or other gastrointestinal (GI) tumors
- Colon polyps
- Bleeding veins in the esophagus or stomach ( esophageal varices and portal hypertensive gastropathy)
- Inflammation of the esophagus ( esophagitis )
- Inflammation of the stomach ( gastritis ) from GI infections
- Hemorrhoids
- Crohn disease or ulcerative colitis
- Peptic ulcer
Other causes of positive test may include:
- Nosebleed
- Coughing up blood and then swallowing it
If the stool guaiac results come back positive for blood in the stool, your doctor will likely order other tests, usually including a colonoscopy .
The stool guaiac test does not diagnose cancer. Screening tests such as colonoscopy can help detect cancer. The stool guaiac test and other screenings can catch colon cancer early, when it is easier to treat.
Risks
There can be false-positive and false-negative results.
Errors are reduced when you follow instructions during collection and avoid certain foods and medicines.
Flushable reagent stool blood test
Stool occult blood test – flushable home test; Fecal occult blood test – flushable home test
Flushable reagent stool blood test is an at-home test to detect hidden blood in the stool.
How the Test is Performed
This test is performed at home with disposable pads. You can buy the pads at the drug store without a prescription. Brand names include EZ-Detect, HomeChek Reveal, and ColoCARE.
You do not handle stool directly with this test. You simply note any changes you see on a card and then mail the results card to your health care provider.
To do the test:
- Urinate if you need to, then flush the toilet before having a bowel movement.
- After the bowel movement, place the disposable pad in the toilet.
- Watch for a change of color on the test area of the pad. Results will appear in about 2 minutes.
- Note the results on the card provided, then flush the pad away.
- Repeat for the next two bowel movements.
The different tests use different ways to check for water quality. Check the package for instructions.
How to Prepare for the Test
Some medicines may interfere with this test.
Check with your provider about changes in your medicines you may need to make. Never stop taking a medicine or change how you take it without first talking to your provider.
Check test package to see if there are any foods you need to stop eating before doing the test.
How the Test will Feel
This test involves only normal bowel functions, and there is no discomfort.
Why the Test is Performed
This test is mainly performed for colorectal cancer screening. It may also be done in the case of low levels of red blood cells (anemia).
Normal Results
A negative result is normal.
Normal value ranges may vary slightly among different labs. Talk to your provider about your test results.
What Abnormal Results Mean
Abnormal results of the flushable pad mean there is bleeding present somewhere in the digestive tract, which may be caused by:
- Swollen, fragile blood vessels in the colon that may result in blood loss
- Colon cancer
- Colon polyps
- Enlarged veins, called varices, in the walls of the esophagus (the tube that connects your throat to your stomach) that bleed
- When the lining of the stomach or the esophagus becomes inflamed or swollen
- Infections in the stomach and intestines
- Hemorrhoids
- Crohn disease or ulcerative colitis
- Ulcer in the stomach or first part of the intestines
Other causes of a positive test, which do not indicate a problem in the gastrointestinal tract, include:
- Coughing up and then swallowing blood
- Nose bleed
Abnormal test results require follow-up with your doctor.
Risks
The test can have false-positive (the test indicates a problem when there actually is none) or false-negative (the test indicates there is NOT a problem, but there is) results. This is similar to other stool smear tests which can also give false results.
Stool ova and parasites exam
Parasites and stool ova exam; Amebiasis – ova and parasites; Giardiasis – ova and parasites; Strongyloidiasis – ova and parasites Taeniasis – ova and parasites
Stool ova and parasites exam is a lab test to look for parasites or eggs (ova) in a stool sample. The parasites are associated with intestinal infections.
How the Test is Performed
A stool sample is needed.
There are many ways to collect the sample. You can collect the sample:
- On plastic wrap. Place the wrap loosely over the toilet bowl so that it is held in place by the toilet seat. Put the sample in a clean container given to you by your health care provider.
- In a test kit that supplies a special toilet tissue. Put it in a clean container given to you by your provider.
Do not mix urine, water, or toilet tissue with the sample.
For children wearing diapers:
- Line the diaper with plastic wrap.
- Position the plastic wrap so that it will prevent urine and stool from mixing. This will provide a better sample.
Return the sample to your provider’s office or lab as directed. At the lab, a small smear of stool is placed on a microscope slide and examined.
How the Test will Feel
The laboratory test does not involve you. There is no discomfort.
Why the Test is Performed
Your provider may order this test if you have signs of parasites, diarrhea that does not go away, or other intestinal symptoms.
Normal Results
There are no parasites or eggs in the stool sample.
Talk to your provider about the meaning of your test results.
What Abnormal Results Mean
An abnormal result means parasites or eggs are present in the stool. This is a sign of a parasitic infection, such as:
- Amebiasis
- Giardiasis
- Strongyloidiasis
- Taeniasis
Risks
There are no risks.
Stool guaiac test
gFOBT; Guaiac smear test; Fecal occult blood test – guaiac smear; Stool occult blood test – guaiac smear
The stool guaiac test looks for hidden (occult) blood in a stool sample. It can find blood even if you cannot see it yourself. It is the most common type of fecal occult blood test (FOBT).
Guaiac is a substance from a plant that is used to coat the FOBT test cards.
How the Test is Performed
Usually, you collect a small sample of stool at home. Sometimes, a doctor may collect a small amount of stool from you during a rectal examination.
If the test is done at home, you use a test kit. Follow the kit instructions exactly. This ensures accurate results. In brief:
- You collect a stool sample from 3 different bowel movements.
- For each bowel movement, you smear a small amount of the stool on a card provided in the kit.
- You mail the card to a laboratory for testing.
DO NOT take stool samples from the toilet bowl water. This can cause errors.
For infants and young children wearing diapers, you can line the diaper with plastic wrap. Place the plastic wrap so that it keeps the stool away from any urine. Mixing of urine and stool can spoil the sample.
How to Prepare for the Test
Some foods can affect test results. Follow instructions about not eating certain foods before the test. These may include:
- Red meat
- Cantaloupe
- Uncooked broccoli
- Turnip
- Radish
- Horseradish
Some medicines may interfere with the test. These include vitamin C, aspirin, and nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen and naproxen. Ask your health care provider if you need to stop taking these before the test. Never stop or change your medicine without first talking to your provider.
How the Test will Feel
The at-home test involves a normal bowel movement. There is no discomfort.
You may have some discomfort if the stool is collected during a rectal exam.
Why the Test is Performed
This test detects blood in the digestive tract. It may be done if:
- You are being screened or tested for colon cancer
- You have abdominal pain, changes in bowel movements, or weight loss
- You have anemia (low blood count)
- You say you have blood in the stool or black, tarry stools
Normal Results
A negative test result means that there is no blood in the stool.
What Abnormal Results Mean
Abnormal results may be due to problems that cause bleeding in the stomach or intestinal tract, including:
- Colon cancer or other gastrointestinal (GI) tumors
- Colon polyps
- Bleeding veins in the esophagus or stomach ( esophageal varices and portal hypertensive gastropathy)
- Inflammation of the esophagus ( esophagitis )
- Inflammation of the stomach ( gastritis ) from GI infections
- Hemorrhoids
- Crohn disease or ulcerative colitis
- Peptic ulcer
Other causes of positive test may include:
- Nosebleed
- Coughing up blood and then swallowing it
If the stool guaiac results come back positive for blood in the stool, your doctor will likely order other tests, usually including a colonoscopy .
The stool guaiac test does not diagnose cancer. Screening tests such as colonoscopy can help detect cancer. The stool guaiac test and other screenings can catch colon cancer early, when it is easier to treat.
Risks
There can be false-positive and false-negative results.
Errors are reduced when you follow instructions during collection and avoid certain foods and medicines.
Fecal smear
Stool smear
Fecal smear is a laboratory test to for a stool sample. This test is done to check for bacteria and other organisms. Presence of organisms in stool shows diseases in the digestive tract.
How the Test is Performed
A stool sample is needed.
There are many ways to collect the sample. You can collect the sample:
- On plastic wrap. Place the wrap loosely over the toilet bowl so that it is held in place by the toilet seat. Put the sample in a clean container given to you by your health care provider.
- In a test kit that supplies a special toilet tissue. Put it in a clean container given to you by your provider.
Do not mix urine, water, or toilet tissue with the sample.
For children wearing diapers:
- Line the diaper with plastic wrap.
- Position the plastic wrap so that it will prevent urine and stool from mixing. This will provide a better sample.
- Put the sample in a container given to you by your health care provider.
Make sure you follow your provider’s instructions for returning the sample. Return the sample to the lab as soon as possible.
The stool sample is sent to a lab where a small amount is placed on a slide. The slide is placed under a microscope and checked for the presence of bacteria, fungi, parasites, or viruses. A stain may be placed on the sample that highlights certain germs under the microscope.
How to Prepare for the Test
There is no preparation needed.
How the Test will Feel
There is no discomfort.
Why the Test is Performed
Your provider may order this test if you have severe diarrhea that will not go away or that keeps returning. The test result may be used to select the correct antibiotic treatment.
Normal Results
A normal result means there are no disease-causing germs present.
Normal value ranges may vary slightly among different labs. Talk to your provider about the meaning of your test results.
What Abnormal Results Mean
An abnormal result means that abnormal germs have been found in the stool sample. This may be due to an infection of the digestive tract.
Risks
There are no risks associated with a fecal smear.
