Stool specimen collection is a diagnostic tool used to evaluate different gastrointestinal conditions. This non-invasive procedure helps to identify infections, diseases, and abnormalities within the digestive tract. Understanding the proper method for collecting stool specimens can lead to accurate results and effective diagnosis and treatment.
Table of Contents
- What is a Stool Specimen Collection?
- Indications
- Fecal Occult Blood Testing (FOBT)
- How to Collect Stool Specimen?
- References and Sources
What is a Stool Specimen Collection?
Collecting stool specimen involves gathering a sample of feces for laboratory analysis. This process can help detect pathogens, blood, fat, parasites, or other abnormalities in the stool, providing essential information about a patient’s digestive health.
Indications
Stool specimens are collected for various diagnostic purposes, including:
- Diagnosing gastrointestinal infections caused by bacteria, viruses, or parasites.
- Detecting occult (hidden) blood in the stool, which may indicate colorectal cancer or other gastrointestinal bleeding.
- Assessing for malabsorption disorders, such as celiac disease or chronic pancreatitis.
- Identifying inflammatory bowel disease (IBD) or irritable bowel syndrome (IBS).
- Monitoring the effectiveness of treatment for certain gastrointestinal conditions.
Fecal Occult Blood Testing (FOBT)
Fecal occult blood testing (FOBT) is a diagnostic tool used to detect hidden (occult) blood in the stool, which may indicate gastrointestinal bleeding. This bleeding can be a sign of various conditions, including colorectal cancer, polyps, ulcers, or inflammatory bowel disease.
FOBT is often used as a screening tool for colorectal cancer, especially in individuals over the age of 50 or those with a family history of the disease.
Types of Fecal Occult Blood Tests
The main types include the guaiac-based FOBT, immunochemical FOBT, and fecal DNA test, each with its own advantages and limitations.
- Guaiac-based FOBT (gFOBT). This test uses a chemical called guaiac to detect heme, a component of hemoglobin in blood. A small sample of stool is smeared onto a test card, and a developer solution is applied. If blood is present, the guaiac will turn blue.
- Immunochemical FOBT (iFOBT or FIT). This test uses antibodies to detect the globin part of human hemoglobin in stool. The patient collects a small sample using a special collection device, which is then sent to the lab for analysis.
- Fecal DNA Test. This test looks for DNA mutations from cancer cells or precancerous polyps in the stool. It also includes an immunochemical test for hemoglobin.
How to Collect Stool Specimen?
Collecting a stool specimen involves preparing the necessary supplies, educating the patient on proper collection techniques, and ensuring the sample is uncontaminated and correctly labeled for accurate laboratory analysis.
Assessment
1. Patient history. Understand the patient’s symptoms, dietary habits, and any medications that might affect the stool sample.
2. Identify indications for stool collection. Determine the reason for stool collection (e.g., infection, occult blood, malabsorption) to guide the collection process.
3. Evaluate the patient’s ability. Assess whether the patient can collect the sample independently or will need assistance.
Planning
The planning process for stool specimen collection includes choosing the correct collection container provided by the laboratory, determining the best timing for sample collection to avoid dietary or medication interference, and educating the patient on the importance of proper collection techniques. This preparation helps achieve accurate sample collection suitable for diagnostic testing.
Delegation
Before delegating stool specimen collection to UAP (Unlicensed Assistive Personnel), nurses must assess the specific requirements. UAP can handle random stool collections, but nurses should conduct stool cultures with sterile swabs.
Preparation
Proper preparation is important to ensure accurate test results. Patients should follow these guidelines:
- Dietary Restrictions. Avoid certain foods that can interfere with test results, such as red meat, beets, and certain medications like nonsteroidal anti-inflammatory drugs (NSAIDs) and vitamin C supplements.
- Hygiene. Clean the genital area to prevent contamination of the stool sample with urine or menstrual blood.
- Collection Kit. A stool collection kit typically includes a sterile collection container, a scoop or spatula, a plastic wrap or liner, gloves, labels, and a biohazard bag.
Implementation
Following these steps ensures that the stool sample collected from the patient is uncontaminated and suitable for laboratory analysis, providing reliable diagnostic information.
1. Wash hands thoroughly with soap and water before starting the collection process.
Ensures cleanliness and prevents contamination of the specimen.
2. Open the collection container provided in the kit.
Ensures the container is ready and accessible during the collection process.
3. Pass stool into a clean, dry container, such as a bedpan or a special plastic collection device placed over the toilet seat.
Prevents contamination of the stool with water or other substances from the toilet bowl.
4. Use the scoop or spatula provided to transfer a small amount of stool into the collection container, ensuring the sample does not exceed the fill line.
Ensures the sample is of adequate size for testing while preventing overfilling, which could cause leakage or contamination.
5. Securely close the lid of the collection container.
Prevents leakage and contamination of the sample.
6. Label the container with the patient’s name, date, and time of collection.
Ensures accurate identification and tracking of the specimen. Typically, three specimens are collected from different bowel movements on consecutive days, with each accurately dated.
7. Store the sample in a cool place or refrigerate if instructed by the healthcare provider.
Preserves the integrity of the sample until it can be analyzed.
8. Wash hands thoroughly after handling the stool sample.
Maintains personal hygiene and prevents the spread of pathogens.
9. Deliver the sample to the laboratory or healthcare provider as soon as possible.
Ensures timely analysis and accurate results.
Nursing Considerations
Patient teaching during stool exams ensures patients understand proper sample collection, handling, and storage procedures, and the importance of timely submission to avoid contamination for accurate results.
1. Consumption of certain foods (e.g., red meat, raw vegetables) can cause false positives in tests for occult blood.
These foods contain peroxidase enzymes or heme, which can mimic the presence of blood in the stool.
2. Some medications, such as NSAIDs or aspirin, can cause gastrointestinal bleeding, leading to false positive results.
These medications can irritate the stomach lining and cause bleeding that may not be related to the underlying condition being tested.
3. Improper collection techniques, such as contamination with urine, menstrual blood, or toilet water, can lead to inaccurate results.
These contaminants can introduce foreign substances or microbes that interfere with the test’s accuracy.
4. Failing to store the sample as instructed can result in degradation or contamination.
Exposure to improper temperatures or conditions can allow bacterial growth or chemical changes that alter the test results, making it unreliable.
5. Instruct the patient to refrain from placing toilet tissue in the bedpan after defecation.
Chemicals in the tissue can interfere with detecting substances like blood or pathogens, and fibers can contaminate the sample, affecting tests for parasites or microscopic analysis.
6. Remove any toilet bowl cleaners and flush the toilet twice before starting the test.
To prevent chemical contamination of the stool sample. This ensures that the sample remains pure and accurate for laboratory analysis, avoiding false results.
References and Sources
- Mathay, C., Hamot, G., Henry, E., Georges, L., Bellora, C., Lebrun, L., … Betsou, F. (2015). Method Optimization for Fecal Sample Collection and Fecal DNA Extraction. Biopreservation and Biobanking, 13(2), 79–93.
- Thomas, V., Clark, J., & Doré, J. (2015). Fecal microbiota analysis: an overview of sample collection methods and sequencing strategies. Future Microbiology, 10(9), 1485–1504.
- Vogtmann, E., Chen, J., Amir, A., Shi, J., Abnet, C. C., Nelson, H., … Sinha, R. (2016). Comparison of Collection Methods for Fecal Samples in Microbiome Studies. American Journal of Epidemiology, 185(2), 115–123.
- Wu, W.-K., Chen, C.-C., Panyod, S., Chen, R.-A., Wu, M.-S., Sheen, L.-Y., & Chang, S.-C. (2018). Optimization of fecal sample processing for microbiome study — The journey from bathroom to bench. Journal of the Formosan Medical Association.