Stool Tests Explained: What They Check For, When to Get One, and What Results Mean

If you’re feeling uncertain about digestive symptoms or worried about what’s going on inside your body, you’re not alone. The good news? A stool test is quick, non-invasive, and often the first step toward clarity and peace of mind.

Also known as faecal tests, they are essential diagnostic tools used to examine the contents of stool for signs of gastrointestinal (GI) diseases, infections, inflammation, and even colorectal cancer. These tests play a crucial role in identifying issues such as bacterial infections, parasitic infestations, digestive disorders, and internal bleeding. By analysing stool samples, healthcare professionals can gather valuable insights into your digestive health and detect conditions early, which is key to effective treatment and management. 

Whether you are experiencing symptoms like abdominal pain or have been advised to undergo routine screening, stool tests provide vital information that supports a thorough diagnosis and informed medical decisions.

What Exactly is a Stool Test and Why is it Important?

A stool test, or faecal test, involves analysing a sample of stool to identify potential issues within the digestive system. The test can detect a variety of substances, such as blood, pathogens (bacteria, viruses, parasites), and signs of inflammation, all of which provide important clues about your gastrointestinal (GI) health. Stool tests can also be used to assess for hidden blood, which may indicate conditions like colorectal cancer or gastrointestinal bleeding.

These tests are vital in diagnosing a wide range of digestive disorders, including infections, inflammatory bowel diseases (IBD), and malabsorption issues. Additionally, stool tests are often used as part of routine screenings, such as for colorectal cancer in individuals over the age of 50 or those with a family history of the disease. 

By identifying problems early, stool tests play a crucial role in the early detection, prevention, and management of GI health issues, helping to ensure timely treatment and better health outcomes.

When Might You Need a Stool Test?

When to consider a stool test often depends on the presence of strange or persistent digestive symptoms, which can be unsettling — especially when they linger or worsen. A stool test helps remove the guesswork and can catch issues early, before they become serious. It may be recommended in various situations to help diagnose gastrointestinal (GI) issues or screen for potential health problems.

Conditions or Symptoms That May Prompt a Stool Test:

• Abdominal Pain: Persistent or unexplained abdominal discomfort can be a sign of digestive issues, infections, or inflammation.
• Diarrhoea or Constipation: Prolonged changes in bowel habits, especially when accompanied by other symptoms, may require a stool test to identify underlying causes.
• Blood or Mucus in Stool: Presence of blood or mucus can indicate infections, inflammation, or more serious conditions like colorectal cancer or haemorrhoids.
• Routine Colorectal Cancer Screening: Stool tests such as the faecal occult blood test (FOBT) or FIT (faecal immunochemical test) are often used to screen for colorectal cancer, especially in individuals over 50 or those with a family history of the disease.
• Chronic Digestive Disorders: Conditions like irritable bowel syndrome (IBS), inflammatory bowel disease (IBD), or celiac disease may require stool tests to monitor and manage symptoms.

Common Types of Stool Tests and What They Check For?

Here’s an overview of the most common stool tests and what a stool test can detect, including the specific conditions and concerns they are used to check for.

Stool Culture Tests

Stool culture tests are used to identify bacterial infections in the digestive system. By growing and isolating bacteria from a stool sample, this test can pinpoint specific pathogens that may be causing gastrointestinal symptoms. Common bacteria detected include Clostridium difficile (C. diff) and Helicobacter pylori, which can lead to severe infections and inflammation. Stool cultures help guide treatment decisions by identifying the responsible bacteria and determining which antibiotics are most effective.

Parasitology Stool Test

The parasitology stool test, also known as an ova and parasite test, involves the microscopic examination of stool to detect parasites. This test is crucial for identifying gastrointestinal infections caused by parasites such as Giardia, Entamoeba histolytica, and Cryptosporidium. Parasitic infections can cause symptoms like diarrhoea, abdominal pain, and nausea. The test is typically requested when a parasitic infection is suspected, especially if the patient has travelled to areas where such infections are more common.

Stool Tests for Gastrointestinal Infections

Stool tests for gastrointestinal infections utilise cultures, microscopy, or molecular methods (DNA/RNA testing) to detect pathogens like bacteria, viruses, and parasites. Common infections diagnosed through these tests include C. difficile, H. pylori, and various enteric viruses and parasites. These tests help healthcare providers determine the specific pathogen responsible for an infection, guiding treatment with the appropriate medications or therapies.

Faecal Occult Blood Tests (FOBT & FIT)

Faecal occult blood tests (FOBT) and faecal immunochemical tests (FIT) are used to detect hidden blood in the stool, a potential sign of colorectal cancer, polyps, or other GI bleeding. gFOBT detects blood using chemical reactions, while FIT uses antibodies to detect human haemoglobin, making it more specific to human blood. These tests are an important part of routine screening for colorectal cancer, particularly for individuals over 50 or those at higher risk due to family history or other factors.

FIT-DNA Tests (e.g., Cologuard)

FIT-DNA tests, such as Cologuard, combine the detection of blood in the stool with DNA analysis to identify genetic mutations that may be present in colorectal cancer cells. This non-invasive test is used as a screening tool for colorectal cancer in individuals at average risk. It is typically recommended every 3 years as part of a preventive health regimen. FIT-DNA tests can detect early-stage cancers or precancerous polyps, providing valuable information for early intervention.

Stool Tests for Inflammation (Faecal Calprotectin)

Faecal calprotectin tests measure the levels of calprotectin, a protein released during inflammation in the intestines. High levels of calprotectin can indicate inflammatory bowel diseases (IBD), such as Crohn’s disease or ulcerative colitis. This test is valuable for diagnosing and monitoring the progression of these chronic conditions, helping to guide treatment decisions and assess disease activity.

Stool Tests for Pancreatic Function (Faecal Elastase and Fat Tests)

Faecal elastase and fat tests are used to assess pancreatic function, particularly in diagnosing conditions like pancreatic insufficiency or malabsorption. Faecal elastase tests measure the enzyme levels in stool to evaluate how well the pancreas is producing digestive enzymes. The fat test examines the amount of fat in the stool, as excessive fat can indicate problems with fat digestion and absorption, which may occur in pancreatic conditions.

Each of these stool tests plays a unique role in diagnosing and managing a wide range of gastrointestinal conditions, providing essential information that aids in treatment planning and disease management.

How to Prepare for Your Stool Test?

Proper preparation is essential to ensure the accuracy of your stool test results. Below are some common guidelines to follow when preparing for your stool test:

1. Dietary Restrictions: In the days leading up to your stool test, avoid consuming certain foods that can affect the accuracy of your results. These may include:
   
   • Red meat can cause false-positive results in faecal occult blood tests (FOBT).
   • Vitamin C supplements may interfere with the chemical reactions in FOBT.
   • High-fibre foods, which can sometimes interfere with tests for inflammation or parasites.
2. Avoid Certain Medications: Some medications can affect stool test results. For instance, non-steroidal anti-inflammatory drugs (NSAIDs) like ibuprofen or aspirin, as well as blood thinners, may need to be paused temporarily before the test. Always consult with your healthcare provider to determine if you should stop any medications before the test.
3. Proper Hygiene and Sample Handling: It’s crucial to handle your stool sample properly to prevent contamination. Make sure to follow the instructions carefully for collecting and storing your sample. Use clean, dry containers and avoid mixing urine or water with the stool.
4. Timing Considerations: For certain stool tests, such as those for gastrointestinal infections or parasites, your doctor may ask you to collect multiple stool samples over a period of time to ensure accurate results.

How to Collect a Stool Sample at Home?

Below is a step-by-step guide to help you understand how to collect a stool sample properly at home, ensuring accuracy and hygiene throughout the process:

1. Gather Your Supplies:
   
   • A clean, dry container or specimen cup provided by your healthcare provider or laboratory.
   • Gloves (optional, but recommended for hygiene).
   • A plastic spoon or spatula (usually provided in the kit).
   • Plastic bags for the disposal of any used materials.
2. Prepare the Collection Area:
   
   • Ensure the area where you will collect the sample is clean. Place the collection container on a flat surface.
   • If you prefer, you can line the toilet with plastic wrap or use a bedpan to catch the stool sample.
3. Collect the Stool Sample:
   
   • Once you’ve had a bowel movement, use the plastic spoon or spatula to transfer a small portion of the stool into the container.
   • For most tests, you only need about 1-2 tablespoons of stool, but check the instructions to be sure. Ensure you take the sample from different areas of the stool (not just from the surface).
4. Seal the Container:
   
   • Carefully seal the container according to the instructions. Make sure it’s tightly closed to prevent leakage.
   • If the test requires multiple samples over a few days, ensure you store each one in the fridge until it is ready to be sent to the lab.
5. Label and Store the Sample:
   
   • Label the container with your name, the date, and any other required information.
   • Store the sample in the refrigerator (unless instructed otherwise) until it is time to submit it.
6. Deliver the Sample:
   
   • Take the sample to the laboratory or your healthcare provider as soon as possible, ideally within 24 hours. Some tests may require prompt delivery to ensure the sample is viable for analysis.

By carefully following these steps, you can help ensure that your stool sample is properly collected and ready for accurate testing. 

How to Understand and Interpret Your Stool Test Results?

While the results will vary depending on the type of test, here’s an overview of how to interpret your findings and what to do next:

1. Positive Results:
   
   • Infections or Pathogens: If the test identifies harmful bacteria, viruses, or parasites (such as C. difficile or Giardia), it indicates an infection that may require treatment with antibiotics, antivirals, or antiparasitics. Your healthcare provider will guide you on the best course of action.
   • Blood in Stool: If blood is detected, particularly in tests like the faecal occult blood test (FOBT), it may indicate bleeding in the gastrointestinal tract. This could be caused by conditions such as haemorrhoids, ulcers, polyps, or even colorectal cancer. Further diagnostic tests, such as a colonoscopy, may be recommended to investigate the cause of bleeding.
2. Negative Results:
   
   • Normal Findings: A negative result typically means there are no signs of infection, blood, or abnormalities in the stool. This is good news, as it suggests your digestive system is functioning normally.
   • No Pathogens Detected: If a stool culture or parasitology test shows no harmful bacteria or parasites, it means no infections were found at the time of testing. However, keep in mind that some infections may not show up in every test, so if symptoms persist, further testing may be required.
3. Unclear or Inconclusive Results:
   
   • Indeterminate Results: Occasionally, stool test results may be unclear or inconclusive. This could be due to improper sample collection, insufficient quantity of stool, or testing issues. In these cases, your healthcare provider may recommend retesting or additional tests to obtain a clearer picture.
   • Follow-up Testing: If your results are inconclusive or if you still have symptoms, further diagnostic tests such as imaging studies or endoscopy may be needed to determine the cause.

If your stool test results indicate an abnormality or infection, your healthcare provider will guide you through the next steps. This may include a prescription for medication, lifestyle changes, or referrals for additional testing or specialists.

Protect Your Health with Regular Stool Tests

Whether you’re dealing with ongoing digestive symptoms or just checking in on your health, a stool test can give you the answers you need — without invasive procedures or long waits. By incorporating stool tests into your routine healthcare, you can detect early signs of gastrointestinal diseases, infections, and even colorectal cancer, allowing for timely intervention and treatment. These tests provide valuable insights into your digestive system, helping you manage chronic conditions and stay ahead of potential health concerns.

If you're due for a screening or have any digestive symptoms, consider discussing stool testing with your healthcare provider. At Centre Vitalab, a private medical laboratory in Montreal, we offer reliable stool tests with fast results, helping you take proactive steps toward better health.

Questions About Stool Tests

Are Stool Tests as Effective as Colonoscopies for Detecting Cancer?

Stool tests and colonoscopies serve different purposes in detecting colorectal cancer. While stool tests, such as the faecal occult blood test (FOBT) or FIT, are excellent for detecting hidden blood or abnormal DNA in the stool, they are not as comprehensive as a colonoscopy. Colonoscopies allow for direct visualisation of the colon and the removal of polyps during the procedure. Stool tests are typically used as an initial screening tool, especially for individuals at average risk of colorectal cancer.

How Long Does it Take to Get Stool Test Results?

The turnaround time for stool test results can vary depending on the type of test and the laboratory's processing time. In general, most stool tests provide results within 24 to 72 hours. However, tests that require culture growth (such as stool cultures for bacterial infections) may take a bit longer.

Can Certain Foods or Medicines Affect My Stool Test Results?

Yes, certain foods, supplements, and medications can affect the accuracy of stool tests. For example:

• Vitamin C can interfere with faecal occult blood tests, leading to false-negative results.
• Red meat can cause false-positive results in FOBT due to the presence of heme, which is similar to blood.
• NSAIDs (non-steroidal anti-inflammatory drugs), blood thinners, and other medications may also affect stool test outcomes, particularly when testing for blood or inflammation.

What Should I Do if My Stool Test is Positive?

If your stool test comes back positive, it doesn't necessarily mean you have a serious condition, but it does warrant further investigation. For example, a positive result for blood in the stool could indicate conditions ranging from haemorrhoids to colorectal cancer. Your healthcare provider will discuss the next steps, which may include follow-up tests, imaging studies (like a colonoscopy), or referral to a specialist for further evaluation and treatment.