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Stool Tests

What is a stool test?

A stool test may also be referred to as a “stool sample,” a “stool culture” or “fecal sample.” This type of test looks at fecal matter for evidence of a medical condition. The test may look for evidence of infection, allergy, blood or digestive problems.

Some stool tests are not cultures. Other stool tests are done to look for evidence of inflammation, bleeding or poor utilization of foods in the intestine. There are many different tests that look for many different conditions that may help explain your child’s illness. To learn what the results mean, it is important to speak with your child’s doctor.

What is a stool culture?

A stool culture may look for bacteria, viruses and other organisms in a patient’s stool. This test can help find out what’s causing a digestive tract infection. There are many types of stool tests for infection done at CHOC Children’s. Your child’s doctor will determine which type of test your child needs based upon his or her symptoms.

For this test, a stool sample is placed in a special container with the nutrients that bacteria or other organisms need to grow. The lab waits until enough organisms are present to be seen under a microscope. Once a doctor knows the type of organism causing an infection, he or she can diagnose and treat the illness.

What is the purpose of a stool culture?

Your child’s physician may request your child submit a stool sample to the lab if he or she thinks your child has a digestive tract infection. Symptoms may include:

  • High fever
  • Stools that contain blood or mucus
  • Severe stomach pain or cramping
  • Severe diarrhea
  • Nausea
  • Diarrhea that lasts more than a few days.

These symptoms are often caused by food poisoning, which is caused by eating food or drinking water that has been contaminated with bacteria, parasites, viruses, or other organisms.

A stool test may also be request if your child has:

  • Immunity problems or if their white blood cell count is high. High white blood cell count is a sign that your child’s body is trying to fight off an infection.
  • Traveled to a region where clean water is unavailable and has symptoms of parasitic infection. A stool test may also be requested if your child has diarrhea that doesn’t go away with treatment.
  • Taken broad-spectrum antibiotics and is at risk for picking up a dangerous strain of bacteria, such as Clostridium difficile.

What do the test results mean?

Many things may affect your child’s lab test results, and even results that are different from the normal value may not mean there is a problem. To learn what the results mean, it is important to speak with your child’s doctor.

  • Normal results are negative, meaning that no germs that usually cause illness were found in the stool culture and that your child doesn’t have an infection.
  • Positive results mean that bacteria, parasites or other germs were found in your child’s stool culture and that they may be causing your child’s stomach problems.
  • Sometimes the test shows a false-negative result, meaning that the test missed certain infectious bacteria. If your child still has symptoms of infection, your child’s doctor may order other tests to find out the cause of their stomach problems.

How is this test done?

This test requires a stool sample. Your child’s doctor will instruct you how to collect a sample into a disposable specimen container with a lid. Stool should not be collected from the toilet bowl or put toilet paper and then into the specimen container. It is important to wear rubber or latex gloves when collecting the sample and be sure to wash your hands thoroughly afterward. The laboratory may give you instructions on how to collect and submit the samples.

Does this test pose any risks?

This test poses no known risks.

What might affect my child’s test results?

Some tests may be affected by medications a child is taking or foods he or she may eat. It is important to tell the child’s doctor about all medicines, herbs, vitamins and supplements your child is taking and to follow any preparation instructions provided.

Types of Stool Tests

There are many types of stool tests. Your child’s doctor will determine the type of stool test (or tests) required to diagnose or guide your child’s treatment. Here are some of the more common tests performed at CHOC Children’s.

Also called a “nucleic acid detection test” and “isolation in cell culture,” this stool test is used to diagnose a rotavirus infection. Rotavirus affects the intestines and causes vomiting and diarrhea. This infection is especially common in young children, but it can affect adults, too. A rotavirus infection causes a condition called viral gastroenteritis.

A rotavirus vaccine is available for children, but it's possible to get infected even after vaccination. There are many different strains of rotavirus, and the vaccine doesn't protect against all of them. It is also possible to get rotavirus more than once, even when vaccinated.

It's best to do this test one to four days after symptoms start, but definitely within eight days of when symptoms start.

The child’s caregiver must collect a stool sample for this test. The doctor will explain how to collect a sample in a disposable specimen container with a lid. Do not collect stool from the toilet bowl or put toilet paper into the specimen container. The doctor will provide instructions on where to turn in the sample.

Also called “yersiniosis test” and “Yersinia stool culture,” this test checks for an infection from the Yersinia bacteria. This infection is also called yersiniosis. Most cases of infection in the U.S. are from a type of bacteria called Yersinia enterocolitica. This illness is most common in children, and it tends to strike more often during the winter. Eating or handling undercooked pork – especially pork chitterlings or intestines – raises the risk for this infection because pigs often carry this type of bacteria.

This test requires a stool sample. Your child’s doctor will instruct you on how to collect a sample in a disposable specimen container with a lid. If your child is unable to produce a stool sample at the time of the test, the doctor may collect stool with a swab inserted into the child’s rectum.

Also called a “stool antigen test,” this test looks for the parasite Giardia intestinalis, which causes an infection of the small bowel called giardiasis or travelers' diarrhea. Symptoms include diarrhea, nausea, vomiting, belly (abdominal) cramps, dehydration, and vague feelings of discomfort. Giardiasis outbreaks are common in daycare centers and among people who travel internationally.

This test requires a stool sample. You may be asked to provide three samples from your child, and the child’s doctor will provide instructions on how to collect a sample in a disposable specimen container with a lid. Do not collect stool from the toilet bowl or put toilet paper into the specimen container.

Barium, anti-diarrhea medicine, antacids and mineral oil can interfere with this test. Antibiotic treatment can also affect the test results.

This test looks for salmonella bacteria in stool. Salmonella infection takes many forms, but the most common in the U.S. is gastroenteritis, also called a "stomach bug." You can get it if you eat food contaminated by animal feces. Food is often contaminated during processing, such as when raw meat comes in contact with other foods. Undercooking meat, especially chicken, can also cause salmonella. Chicken eggs are a common carrier of salmonella. Typhoid fever is another type of salmonella that may affect people who travel outside the U.S. Salmonella can also cause an invasive disease like osteomyelitis, or bone infection.

This test requires a stool sample. Your child’s doctor will explain how to collect the sample and place it in a disposable specimen container with a lid. Don't collect fecal material from the toilet bowl or put toilet paper into the specimen container.

Also called a “stool white blood cell test” or “fecal leukocyte test,” this test looks for white blood cells in stool. This test can help your child’s doctor determine if there is inflammation in the intestine that might require treatment or further testing.

White blood cells, also called leukocytes, are immune system cells that can show up in the stool if you have inflammatory diarrhea. This type of diarrhea may be a symptom of an infection caused by bacteria such as Shigella, Clostridium difficile, Campylobacter, or Salmonella. It may also occur in inflammatory bowel disease, such as Crohn's disease or ulcerative colitis.

Your child’s doctor will provide a special container with a tightly fitting lid to place the stool sample in. If your child isn’t able to produce a stool sample, the doctor may collect a sample by inserting a swab into his or her rectum.

Urine or toilet paper may contaminate the sample, affecting the results. Drinking milk can affect the results.

Also referred to as fecal calprotectin, this test looks for white blood cells in the stool. This test can help your child’s doctor determine if there is inflammation in the intestine that might require treatment of further testing.

This test requires a stool sample. Your child’s doctor will explain how to collect a sample into a disposable specimen container with a lid. Do not collect fecal material from the toilet bowl or put toilet paper into the specimen container.

More Stool Tests

Also called “FOBT” or “stool occult blood,” this test checks for blood that can't be seen with the naked eye. Blood in the stool is a sign of bleeding in the digestive tract. This could indicate cancer, polyps, hemorrhoids, diverticulosis or inflammatory bowel disease.

Your child’s doctor will provide a kit to help you collect and prepare bowel movement samples for the fecal occult blood test. The test requires collecting samples from more than one bowel movement – typically, three in a row. You then mail the samples to a lab or return them to your doctor's office.

Collecting and preparing the samples typically follows these steps:

  1. After putting on protective gloves, collect one of the stools in a dry container. Don't allow urine to mix with it.
  2. Use a wooden applicator to put a small smear of stool on a card or slide.
  3. Flush the unused stool down the toilet.
  4. Seal the sample and write your child’s name and date on it.
  5. Repeat this process for the next two stools, or as instructed.

It is important to follow specific instructions before starting this stool test:

  • The child should not take nonsteroidal anti-inflammatory drugs, such as ibuprofen (Advil) or naproxen (Aleve), or aspirin for seven days before the test. Acetaminophen (Tylenol) is safe to use.
  • The child should not take vitamin C supplements or drink or eat juice or fruits high in vitamin C for seven days before the test. Vitamin C can cause a false-negative test result.
  • The child should not eat red meat, such as beef, lamb, pork, and liver, for three days before testing. Although it's unlikely, these foods could alter your test result.

This test checks stool sample for trypsin and chymotrypsin, two enzymes made by the pancreas. It measures how well the pancreas is working in patients with cystic fibrosis (CF). Based on the results from this test, the child’s doctor may prescribe replacement pancreatic enzymes.

This test requires a stool sample. Your child’s doctor may ask you to collect a single stool sample or all of bowel movements during a 72-hour period.

Also referred to as “C. diff” and “C. difficile,” this test looks for toxins produced by Clostridium difficile bacteria.

This test requires a stool sample. Your child’s doctor will explain how to collect a sample into a disposable specimen container with a lid. Do not collect fecal material from the toilet bowl or put toilet paper into the specimen container.

Also referred to as “stool sample examination,” “stool O&P” and “fecal smear,” this test looks for parasites and their larvae or eggs in a sample of stool.

Parasites are organisms that can live within or on the human body and rely on it as a source of food. Many live in the digestive tract. Many parasites also cause illnesses. These include one-celled organisms, such as Giardia, and larger organisms such as pinworms. In their adult form, pinworms can usually large enough to be seen.

This test requires a stool sample. Your child’s doctor will tell you how to collect the sample. Don't collect fecal material from the toilet bowl or put toilet paper into the specimen container.

Certain medications can affect test results. This can be true for up to one week after the medications are taken. These medications include:

  • Antacids
  • Bismuth
  • Some drugs used to treat diarrhea
  • Barium
  • Antibiotics
  • Oily laxatives.

A sample contaminated by urine or toilet water may have an inaccurate result. Timing is also important. If the sample isn't brought to the lab promptly, the results may not be accurate.

Also referred to asfat in stool,” “fecal fat stain” and “quantitative stool fat,” this test measures the amount of fat in a patient’s stool. Having too much fat in one’s stool is called steatorrhea. If a patient has too much fat in their stool, it may be a sign that food is moving through their digestive system without being broken down and absorbed properly. This is called malabsorption. Having a fecal fat test is the best way to find out if a child has malabsorption.

This test requires a stool sample. The method of collecting a stool sample varies depending on the type of fecal fat test you need. Your child’s doctor will explain how to collect and store the samples.

There are two types of fecal fat tests: qualitative and quantitative. For a qualitative test, the lab checks a single stool sample under a microscope to count the number of fat globules, or droplets. For a quantitative test, you will need to collect your child’s stool samples over two to four days. These samples are measured to find the total amount of fat in his or her stool each day.

Many things may affect lab test results. These include the method each lab uses to do the test. Even if test results are different from the normal value, the child may not have a problem. To learn what the results mean, it is important to talk with your child’s doctor.

A qualitative fecal fat test counts the number of fat globules in stool. This test measures two types of fat globules: neutral fat and fatty acids. Normal results are:

  • Fewer than 50 neutral fat globules seen under the microscope
  • Fewer than 100 fatty acid fat globules seen under the microscope
Results for a quantitative fecal fat test are given in grams per 24 hours (g/24 h). Normal results are:
  • 2 to 7 g/24 h for adults, with fat being less than 20 percent of the solid stool sample
  • Less than 1 g/24 h for an infant: - In bottle-fed babies, fat should make up 30 to 50 percent of the sample - In breastfed babies, fat should make up 10 to 40 percent of the sample

Your child’s results can be affected by several things. These include:

  • Using a rectal suppository or oily rectal cream
  • Swallowing castor oil or mineral oil
  • Not eating a balanced diet
  • Eating too much fiber or taking a fiber-based stool softener
  • Contaminating the stool sample with urine.

Depending on the type of fecal fat test, your child may need to follow a special diet and not use laxatives. Your child’s doctor will provide specific information on how to prepare for the test.

Also called a “stool sample examination” and “fecal (poop) smear,” this test looks for harmful bacteria in a culture sample from stool.

One kind of harmful bacteria is Campylobacter. It is the leading cause of foodborne illness in the U.S. Although Campylobacter shows up in the stomach of several animals, including pigs and cattle, it is usually passed to people through raw and undercooked chicken and other poultry. In some cases, people have become infected through unpasteurized milk and city water supplies contaminated with Campylobacter.

The infection usually runs its course in about a week without any treatment. Other infections may develop, though. They include:

  • Meningitis
  • Inflammation of the joints
  • Urinary tract infection.

In rare cases, Campylobacter infection may also lead to Guillain-Barré syndrome. This is a nerve disease that can cause temporary paralysis.

This test can tell your health care provider whether you have Campylobacter or a different type of harmful bacteria in your digestive tract.

This test requires a sample of your child’s stool. His or her doctor will explain how to collect and deliver the sample. If your child isn’t able to give a stool sample, your provider may take the sample by putting a swab into your rectum.

Timing is important. If your child has been in the hospital for more than three days, his or her results may not be accurate. Contaminating the sample with urine or toilet paper can affect the results.

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