Collecting Stool Specimen

A stool specimen is a noninvasive window into the GI tract. It picks up infections, hidden blood, fat, parasites, and other abnormalities, and the quality of your collection drives the quality of the result. Collect it sloppily and you get a sloppy answer.

What It Is

You gather a sample of feces for lab analysis. Done right, it detects pathogens, blood, fat, parasites, and other abnormalities, and tells you a lot about the patient's digestive health.

Indications

• Diagnosing GI infections from bacteria, viruses, or parasites
• Detecting occult (hidden) blood, which can point to colorectal cancer or other GI bleeding
• Assessing malabsorption disorders like celiac disease or chronic pancreatitis
• Identifying inflammatory bowel disease (IBD) or irritable bowel syndrome (IBS)
• Monitoring how well treatment is working for a GI condition

Fecal Occult Blood Testing (FOBT)

FOBT detects hidden blood in the stool, a sign of GI bleeding that can come from colorectal cancer, polyps, ulcers, or inflammatory bowel disease. It is a common colorectal cancer screen, especially for people over the age of 50 or those with a family history.

Types

1. Guaiac-based FOBT (gFOBT). Uses guaiac to detect heme, a component of hemoglobin. You smear a small stool sample on a test card and apply developer solution. If blood is present, the guaiac turns blue.
2. Immunochemical FOBT (iFOBT or FIT). Uses antibodies to detect the globin part of human hemoglobin. The patient collects a small sample with a special device that goes to the lab.
3. Fecal DNA test. Looks for DNA mutations from cancer cells or precancerous polyps, and includes an immunochemical test for hemoglobin.

How to Collect

Assessment

1. Patient history. Symptoms, diet, and any medications that could affect the sample.
2. Indication. Know why you are collecting (infection, occult blood, malabsorption). It shapes the method.
3. Patient ability. Can they collect it themselves, or do they need help?

Planning

Pick the right lab-provided container, time the collection to avoid dietary or medication interference, and teach the patient why technique matters.

Delegation. UAP can handle random stool collections. The nurse handles stool cultures with sterile swabs.

Preparation. Walk the patient through:

• Dietary restrictions. Avoid foods and drugs that skew results: red meat, beets, NSAIDs, and vitamin C supplements.
• Hygiene. Clean the genital area so urine or menstrual blood does not contaminate the sample.
• Collection kit. Usually a sterile container, scoop or spatula, plastic wrap or liner, gloves, labels, and a biohazard bag.

Implementation

1. Wash your hands with soap and water before you start.
2. Open the collection container from the kit so it is ready.
3. Pass stool into a clean, dry container, like a bedpan or a plastic collection device over the toilet seat, so it does not mix with toilet water.
4. Transfer a small amount with the scoop or spatula, staying under the fill line. Enough to test, not so much it leaks.
5. Close the lid securely to prevent leakage and contamination.
6. Label with the patient's name, date, and time. Typically you collect three specimens from different bowel movements on consecutive days, each dated.
7. Store cool or refrigerate if instructed, to preserve the sample.
8. Wash your hands after handling the sample.
9. Get it to the lab as soon as possible for timely, accurate results.

Nursing Considerations

Teach the patient how to collect, handle, and store the sample, and why timing matters. Watch for the things that wreck results:

1. Certain foods (red meat, raw vegetables) cause false positives on occult blood tests. They carry peroxidase enzymes or heme that mimic blood.
2. NSAIDs or aspirin can cause GI bleeding and a false positive unrelated to what you are testing for.
3. Contamination with urine, menstrual blood, or toilet water skews results by introducing foreign substances or microbes.
4. Improper storage lets the sample degrade. The wrong temperature allows bacterial growth or chemical changes that make it unreliable.
5. No toilet tissue in the bedpan after defecation. Tissue chemicals interfere with detecting blood or pathogens, and fibers contaminate the sample.
6. Remove toilet bowl cleaners and flush the toilet twice before the test, so chemicals do not contaminate the sample.