Stool Test: Types, Preparation, and Interpretation

Dec 13, 2024 | 6 min read

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A stool test helps detect infections, digestive disorders, and colon cancer. Early diagnosis through this non-invasive test ensures timely and effective treatment.

What Is a Stool Test?

A stool test, also known as a fecal test or fecal analysis, examines a sample of stool to detect health issues. Healthcare providers use this simple, non-invasive test to find the causes of gastrointestinal (GI) symptoms and diagnose infections, digestive disorders, and colorectal cancer.

The test checks for bacteria, viruses, or parasites that may cause illness. It can also detect hidden blood in the stool, which might indicate bleeding in the digestive tract. 

Stool tests play an essential role in screening for colorectal cancer, helping to identify it early when treatment is most effective.

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Doctors recommend a stool test when you experience symptoms that may point to digestive issues. Common signs include:

  • Blood in stool, visible or hidden.
  • Persistent diarrhea or ongoing constipation.
  • Abdominal pain or cramping that does not go away.
  • Unexplained weight loss or ongoing fatigue.
  • Bowel leakage or difficulty controlling bowel movements.

These symptoms often signal underlying health problems that need investigation.

Conditions Stool Tests Detect

Stool tests help identify a variety of gastrointestinal and digestive conditions, including:

  • Hemorrhoids and Anal Fissures: Swollen veins or small tears in the anus that can cause pain, discomfort, or bleeding.
  • Colorectal cancer: Early detection of cancer or precancerous polyps in the colon or rectum.
  • Diverticulosis: Small bulging pockets in the intestinal wall that can cause discomfort or infection.
  • Inflammatory bowel disease (IBD): Chronic inflammation in the digestive tract, including Crohn’s disease and ulcerative colitis.
  • Gastrointestinal infections: Bacteria, viruses, or parasites can cause diarrhea, fever, and stomach pain.
  • Steatorrhea: Excess fat in the stool, often linked to malabsorption or pancreatic issues.
  • Gastrointestinal bleeding: Hidden or visible blood in the stool, which can indicate ulcers, cancer, or inflammation.
  • Stomach ulcers: Stomach ulcers are open sores in the stomach lining that result from infections or other issues.
  • Exocrine pancreatic insufficiency: Inability to properly digest food due to a lack of pancreatic enzymes.
  • Colitis: Swelling or irritation of the colon, often linked to infections or autoimmune diseases.
  • Anemia-related issues: Hidden blood loss in the stool that can contribute to low red blood cell counts.

Types of Stool Tests

Stool tests help doctors find out what’s causing digestive problems or check for specific health conditions. Different types of stool tests are available, and your doctor will recommend the best one based on your symptoms.

Routine Stool Analysis

A routine stool analysis examines the appearance, consistency, and composition of stool to identify digestive issues. 

This test checks for abnormalities like mucus, blood, pus, or undigested food

It also evaluates stool color and pH levels, which can provide clues about infections, malabsorption, or other gastrointestinal disorders. 

Routine stool analysis is often the first step when diagnosing digestive problems.

Screening for Blood

Some stool tests check for hidden blood, which can be a sign of bleeding in the digestive system or colorectal cancer.

Fecal Occult Blood Test (FOBT)

This test looks for blood in the stool that you can’t see. You place a small stool sample on a special card, and a chemical is added. If the card changes color, it means there might be blood. 

Before this test, you might need to avoid certain foods like red meat, broccoli, and turnips to ensure accurate results. Medications such as aspirin, NSAIDs, or vitamin C supplements may also be avoided.

Fecal Immunochemical Test (FIT)

FIT also looks for hidden blood, but it uses antibodies that specifically detect human blood. 

Unlike FOBT, there are no dietary restrictions, and it’s easier to prepare. This test is often more accurate because it focuses on blood from the lower digestive system, like the colon or rectum.

Detecting Infections

These tests determine if an infection causes diarrhea, stomach pain, or fever.

Stool culture for bacteria

This test checks for harmful bacteria, like Salmonella or E. coli, that shouldn’t be in your digestive system. 

The stool sample is placed in a lab to see if bacteria grow. If bacteria are found, doctors can figure out which antibiotics might work best.

Ova and Parasite (O&P) test

This test checks for eggs (ova) and parasites in the stool. It is often used for long-term diarrhea or after travel to areas with common parasitic infections, such as Southeast Asia, Sub-Saharan Africa, or Central America.

The lab examines the stool under a microscope to detect parasites like Giardia lamblia or Entamoeba histolytica.

Tests for specific pathogens

Some tests are designed to look for specific infections. For example, a stool test can find Helicobacter pylori, a type of bacteria that causes stomach ulcers and may increase the risk of stomach cancer.

Specialized Tests

Fecal fat test for malabsorption

This test checks for extra fat in your stool, which can mean your body isn’t absorbing nutrients properly. It’s often done if you have greasy stools, weight loss, or other symptoms of malabsorption.

Calprotectin and lactoferrin tests

These tests check for inflammation in your digestive system and help diagnose or monitor conditions like Crohn’s disease and ulcerative colitis.

Calprotectin is a protein released during intestinal inflammation. High levels can indicate inflammatory bowel disease (IBD), like Crohn’s or ulcerative colitis. This test also helps track how well treatments are working.

Lactoferrin is another marker of inflammation. It shows how active the inflammation is and helps doctors decide if further tests, like a colonoscopy, are needed.

Both tests use a stool sample to detect inflammation and track treatment progress.

DNA stool tests for cancer detection

These advanced tests look for abnormal DNA in the stool that could be a sign of cancer or precancerous growths. They are highly sensitive and can find signs of colorectal cancer early, often before symptoms appear.

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How to Prepare for a Stool Test

Proper preparation for a stool test ensures accurate results and avoids the need for a repeat test. Follow these simple recommendations before collecting your sample.

Pre-Test Instructions

Your doctor may ask you to avoid certain foods or medications that could affect the test. 

For example, some tests require avoiding red meat, iron supplements, or certain medications like NSAIDs. Always follow the specific instructions provided.

Some stool tests require a single sample, while others may need multiple samples collected over a few days. Check with your doctor or lab to understand how and when to collect your samples.

Common Mistakes to Avoid

One common mistake is contaminating the stool sample with urine or water. To prevent this, pee before collecting your stool and ensure the sample does not touch water from the toilet. 

Another mistake is storing the sample improperly. Some samples need refrigeration, while others must stay at room temperature. Incorrect storage can ruin the sample and produce inaccurate results. 

Always follow the storage instructions provided by your doctor or lab.

How to Collect a Stool Sample

Collecting a stool sample may seem hard, but it’s simple with the right steps. Whether for yourself or a child, proper collection ensures reliable test results.

Step-by-Step Instructions for Adults

  1. Get the supplies from your doctor or lab, like the container and scoop.
  2. Use a clean container or plastic wrap over the toilet to catch the stool. Don’t let it touch the toilet.
  3. Put a small amount of stool into the container using the scoop or a disposable spoon. Follow the size instructions.
  4. Close the container tightly to keep it clean and safe.
  5. Throw away any leftover stool and used items in a sealed bag.
  6. Wash your hands well with soap and water.

Special Considerations for Infants and Toddlers

For infants or toddlers, collecting a stool sample requires a slightly different approach. You can line the diaper with plastic wrap to prevent the stool from being absorbed into the diaper material. 

If the child uses a potty, place a clean plastic container inside to catch the stool directly. 

Transfer some stool into the sample container using a clean scoop and seal it tightly. Follow your doctor’s storage instructions for accurate results.

Normal Stool Characteristics

Healthy stool is usually brown, soft, and well-formed. It should not contain visible blood, mucus, or harmful pathogens. 

Normal results indicate that your digestive system is functioning properly, and no signs of infection, inflammation, or other issues were detected.

What Happens After Abnormal Results?

If your stool test results are abnormal, your doctor will recommend additional tests or treatments based on the findings.

Doctors may recommend a colonoscopy or CT scan to examine the digestive tract and identify underlying issues. In some cases, blood tests may be ordered to confirm or rule out specific conditions.

Treatment depends on the cause of the abnormal results. For infections, doctors may prescribe medications for bacteria, parasites, or other pathogens. 

Malabsorption or inflammation may require dietary changes or supplements. In complex cases, like cancer or growths, doctors may refer you to a specialist. 

Quick follow-up is key to managing and resolving health issues effectively.

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Conclusion

Stool tests are vital for diagnosing various health conditions, including gastrointestinal infections, inflammatory bowel diseases, and colon cancer. 

Common types include tests for hidden blood, such as FOBT and FIT. Other tests detect infections with stool cultures and parasite exams or check for issues like malabsorption and early cancer.

Early diagnosis through stool tests allows for timely treatment and better health outcomes.

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