A stool sample, also known as a fecal sample, is a small amount of a person’s feces collected for laboratory analysis. This type of test helps healthcare professionals identify various conditions affecting the digestive system, such as infections from bacteria, viruses, or parasites, as well as inflammatory bowel diseases, digestive problems, and even certain cancers. By examining the sample, doctors can gain insights into what might be causing gastrointestinal symptoms.
The Required Amount
The specific quantity of stool needed varies by test and laboratory requirements. Generally, a small amount is sufficient, often described as about the size of a walnut or approximately one tablespoon. For certain tests, such as those for ova and parasites, a sample equivalent to two large walnuts or two tablespoons of liquid stool may be requested. Some collection kits for specific tests, like those for fecal immunochemical tests (FIT), may include a fill line on the container to indicate the precise amount required. It is important to consult the detailed instructions provided by your healthcare provider or within the collection kit, as these guidelines ensure accurate testing.
Why Quantity Matters
Providing the correct quantity of stool ensures accurate and reliable laboratory test results. An adequate sample size allows the lab to perform all necessary analyses, including microscopic examination, chemical tests, and microbiologic cultures, without needing a repeat collection. Insufficient amounts of stool can lead to inconclusive results, as there may not be enough material to detect disease-causing organisms or markers. For instance, certain tests for parasites may require at least 2-5 grams of stool, and sometimes multiple samples collected over several days, to increase the chance of detection. Too little or unrepresentative fecal material can cause analysis to fail, potentially delaying diagnosis and treatment.
Guidance for Sample Collection
Collecting a stool sample at home requires careful attention to hygiene and proper handling to avoid contamination and ensure accurate test results. Before beginning, wash your hands thoroughly with soap and water, and consider wearing disposable gloves. To prevent contamination from urine or toilet water, it is recommended to urinate before collecting the sample and to use a collection device, such as a hat-shaped plastic container, plastic wrap, or newspaper placed over the toilet bowl. The sample should be collected directly into the provided sterile container, avoiding contact with the toilet bowl. If the stool is watery or contains blood or mucus, include those parts in the sample.
After collecting the appropriate amount, use the provided scoop or stick to transfer the stool into the specimen container, filling it to the indicated line if present. Securely close the lid to prevent leakage and label the container clearly with your name, date of birth, and the date and time of collection. Any remaining stool can be flushed, and all used collection materials should be disposed of in a plastic bag. Most samples need to be delivered to the lab as soon as possible, often within 24 hours, and may require refrigeration if immediate transport is not feasible.