What It Is A stool (feces) sample can provide doctors with valuable information about what's going on when your child has a problem in the stomach, intestines, rectum, or other part of the gastrointestinal (GI) system. One of the most common reasons to collect a sample is to determine if there's blood in the stool. Sometimes harmful bacteria or parasites can cause a variety of conditions, such as bloody diarrhea. It may be necessary to examine the stool under a microscope and perform other tests to find the cause of the problem. To test the stool for the presence of blood, a noninvasive test called the fecal occult blood test (FOBT) is performed. The test detects hidden (occult) blood in the stool — blood that cannot be seen by the naked eye. Blood may come from any part of the digestive tract, from the esophagus to the anal area. Sometimes, blood detected in the stool can come from swallowed blood if the child has had bleeding from the mouth, throat or nose. Why It's Done A doctor may request a fecal occult blood test to look for blood that's present due to causes such as: allergies or inflammation gastrointestinal infection caused by bacteria, viruses, or parasites bleeding in the GI tract from ulcers and other problems polyps Preparation Unlike most other lab tests, a stool sample is often collected by parents at home, not by health care professionals at a hospital or clinic. For a week before the test, your child may be asked to avoid certain foods and medications such as: aspirin anti-inflammatory drugs such as ibuprofen vitamin C supplements Procedure The doctor or hospital laboratory will usually provide written instructions on how to collect a stool sample. If instructions aren't provided, here are tips for collecting a stool sample from your child: Be sure to wear latex gloves and wash your hands and your child's hands afterward. Many kids with diarrhea, especially young kids, can't always let a parent know in advance when a bowel movement is coming. So a hat-shaped plastic lid is used to collect the stool specimen. This catching device can be quickly placed over a toilet bowl, or under your child's bottom, to collect the sample. Using a catching device can prevent contamination of the stool by water and dirt. Another way to collect a stool sample is to loosely place plastic wrap over the toilet seat. Then place the stool sample in a clean, sealable container before taking it to the lab. Plastic wrap can also be used to line the diaper of an infant or toddler who isn't yet using the toilet. The stool should be collected into clean, dry plastic jars with screw-cap lids. Your child may be asked to provide a stool sample one or more times. For best results, the stool should be brought to the lab right away. If this isn't possible, the stool should be refrigerated and then taken to the lab as soon as possible. What to Expect When the sample arrives at the laboratory, it's checked for blood by placing a smear of the stool on special paper. A chemical solution called guiac is then placed on the paper with the stool smear. If the paper turns blue, this means there's blood in the stool. Getting the Results In general, the result of the fecal occult blood test is reported within a day. Risks No risks are associated with collecting stool samples. Helping Your Child Collecting a stool sample is painless. Tell your child that collecting the stool won't hurt, but it has to be done carefully. A child who is old enough might be able to collect the sample alone to avoid embarrassment. Instruct your child how to do this properly. If You Have Questions If you have questions about the fecal occult blood test, speak with your doctor. Back to Articles Related Articles Stool Test: Bacteria Culture A stool culture helps doctors determine if there's a bacterial infection in the intestines. Read More Stool Test: Giardia Antigen This test may be done if a child has watery diarrhea, abdominal pain, large amounts of intestinal gas, appetite loss, and nausea or vomiting. Read More A to Z Symptom: Rectal Bleeding Learn about some common causes of rectal bleeding, most of which aren't serious. Read More Amebiasis Amebiasis is an intestinal illness transmitted when someone eats or drinks something that's contaminated with a microscopic parasite. Read More Stool Test: C. Difficile Toxin A doctor may request a C. difficile toxin stool test if your child has taken antibiotics in the past month or so and has had diarrhea for several days. Read More Stool Test: H. Pylori Antigen A doctor may request an H. pylori antigen stool test if your child has symptoms that indicate a peptic ulcer, such as indigestion, abdominal pain, a full or bloated feeling, nausea, frequent belching, or vomiting. Read More Stool Tests Your child's doctor may order a stool collection test to check for blood, bacteria, ova, or parasites. Find out how this test is performed and when you can expect the results. Read More Campylobacter Infections These bacterial infections can cause diarrhea, cramping, abdominal pain, and fever. Good hand-washing and food safety habits can help prevent them. Read More Giardiasis Giardiasis, one of the chief causes of diarrhea in the United States, is an intestinal illness caused by a microscopic parasite. Read More Diarrhea Most kids battle diarrhea from time to time, so it's important to know what to do to relieve and even prevent it. Read More Note: All information is for educational purposes only. For specific medical advice, diagnoses, and treatment, consult your doctor. © 1995-2021 KidsHealth®. All rights reserved. Images provided by The Nemours Foundation, iStock, Getty Images, Veer, Shutterstock, and Clipart.com.