Helicobacter pylori test and how to interpret it: when is it positive

Do you experience stomach pain or ongoing digestive problems? If symptoms such as heartburn, nausea, or bloating are bothering you, Helicobacter pylori (H. pylori) may be the underlying cause. This bacterium is one of the most common causes of stomach ulcers and digestive system disorders. But how can you be sure it’s the reason behind your symptoms? Fortunately, several diagnostic tests can help confirm the presence of H. pylori. However, with multiple options available—such as blood tests, stool tests, breath tests, and others—you may feel confused about which test is best for you.In this Dalily Medical article, we’ll explore the different types of H. pylori tests in detail, explain how to accurately read and understand test results, and clarify when a result is considered positive and indicates an active infection. Discover everything you need to know about diagnosing H. pylori and taking the next step toward effective treatment for better digestive health.

What Is the H. pylori Test?

The H. pylori test is a medical test used to detect Helicobacter pylori (H. pylori) bacteria, which are the main cause of stomach ulcers and peptic ulcer disease. This bacterium infects the stomach and the upper part of the small intestine and can cause irritation and inflammation of the stomach lining, leading to uncomfortable symptoms such as heartburn, stomach pain, and nausea.
If left untreated, H. pylori infection may increase the risk of stomach cancer. Therefore, doctors usually request this test when a patient shows symptoms of stomach ulcers or signs of gastritis.

Types of H. pylori Tests

There are four main tests used to detect H. pylori infection:

Stool test: Detects H. pylori antigens in the stool.
Blood test: Detects antibodies against H. pylori in the blood.
Breath test (Urea Breath Test): Based on drinking a urea-containing solution and measuring the carbon dioxide produced.
Upper endoscopy test: Direct examination of the stomach and small intestine using a small camera.

Why Is the H. pylori Test Performed?

The H. pylori test is usually requested to confirm whether stomach symptoms are caused by this bacterium. H. pylori can lead to chronic conditions such as stomach ulcers, gastritis, and in some cases may increase the risk of stomach cancer if not properly treated.

Can H. pylori Test Results Be Falsely Positive?

Yes, in some cases the test result may be false positive. This can occur due to taking certain medications such as antibiotics or acid-reducing drugs before testing. That’s why it’s important to follow your doctor’s instructions regarding stopping medications before the test to ensure accurate results.

What Is the Name of the Breath Test for H. pylori?

It is called the Urea Breath Test or H. pylori Breath Test.
It is used both to detect active infection and to assess treatment effectiveness after therapy.

Does the Test Require Special Preparation?

Yes, preparation depends on the type of test:

Blood test & breath test:
Stop antibiotics and proton pump inhibitors (PPIs) for 4–6 weeks before testing.
Stool test:
Avoid medications containing bismuth for 2–3 days before testing.

What Does a Positive Result Mean?

A positive result means that H. pylori bacteria are present in the stomach. In this case, treatment with antibiotics is necessary to relieve symptoms and prevent complications such as ulcers or gastritis.

What Does a Negative Result Mean?

A negative result means there is no current evidence of H. pylori infection.
However, if symptoms persist, the doctor may recommend additional tests to identify the cause.

Can Test Results Be Inaccurate?

Yes, several factors may affect test accuracy, including:

Taking antibiotics or acid-suppressing medications before testing
The testing method used
Timing and quality of sample collection, especially in stool tests

For this reason, doctors may request confirmatory tests if results are unclear.

Can the H. pylori Test Be Done During Pregnancy?

Yes, testing can be done during pregnancy, but medical consultation is required first. Some medications used to treat H. pylori may not be safe during pregnancy.

Can Diet Affect Test Results?

Yes. Spicy foods or alcohol before testing may affect accuracy, especially with the breath test. It’s best to avoid food and drinks for a period before testing, as advised by your doctor.

When Should the Test Be Repeated?

After completing antibiotic treatment, a follow-up test is usually recommended after 4–6 weeks to confirm eradication of the bacteria.

How Long Does It Take to Get Results?

Blood test: 1–2 days
Breath test: Same day
Stool test: 1–3 days

Is the Test Necessary If I Have Stomach Pain?

If you experience stomach pain, bloating, or indigestion, an H. pylori test is recommended to determine the cause. However, not all stomach pain is caused by H. pylori.

Can H. pylori Be Treated Without Testing?

No. Treating without testing is not recommended. Using antibiotics unnecessarily can lead to antibiotic resistance and unwanted side effects.

Can Children Take the H. pylori Test?

Yes, children can be tested for H. pylori. The test method depends on the child’s age and health condition, and the doctor will choose the most appropriate option.

Types of H. pylori Diagnostic Tests and How They Are Performed

1️⃣ Urea Breath Test

How it’s done:

Fast for 4–6 hours before the test
Drink a solution containing labeled urea
If H. pylori is present, it converts urea into carbon dioxide
Breath samples are collected and analyzed

Advantages:

Fast and painless
Highly accurate before and after treatment

Disadvantages:

Antibiotics, PPIs, and bismuth must be stopped beforehand to avoid false results

2️⃣ Blood Test (Serology Test)

How it’s done:

A blood sample is taken from the arm
Antibodies against H. pylori are measured

Advantages:

Simple and non-invasive
Useful for initial screening

Disadvantages:

Cannot confirm active infection
Not suitable for monitoring treatment success

3️⃣ Stool Antigen Test

How it’s done:

A small stool sample is collected in a clean container
The lab checks for H. pylori antigens

Advantages:

Very accurate before and after treatment
Non-invasive and suitable for both children and adults

Disadvantages:

Sample collection may be inconvenient
Certain medications may affect accuracy

4️⃣ Endoscopic Biopsy

How it’s done:

Upper endoscopy is performed using a thin tube with a camera
Small tissue samples are taken from the stomach lining
Samples are tested using microscopy, rapid urease test, or bacterial culture

Advantages:

Most accurate diagnostic method
Allows evaluation of ulcers, gastritis, or abnormal tissue changes

Disadvantages:

Invasive procedure requiring mild sedation
More expensive and less comfortable than non-invasive tests

H. pylori Test Results

1️⃣ Urea Breath Test

Positive result:

Indicates active H. pylori infection
Antibiotic and acid-suppressing treatment is initiated

Negative result:

No active infection detected
Recent use of antibiotics, PPIs, or bismuth may cause false-negative results

2️⃣ Blood Test (Serology)

Positive result:

Indicates exposure to H. pylori in the past or present

Negative result:

Usually means no prior exposure

Limitation:

Cannot distinguish between past and current infection

3️⃣ Stool Antigen Test

Positive result:

The presence of H. pylori antigens indicates an active infection.
It is also used to confirm treatment success after completing antibiotics.

Negative result:

No antigens detected, which usually means the bacteria are not present.

Note:

Some medications may cause false-negative results, so proper preparation is important.

4️⃣ Endoscopic Biopsy

Positive result:

Detection of H. pylori in biopsy samples confirms an active infection.
Provides information about damage to the stomach lining or the presence of ulcers.

Negative result:

No bacteria detected, usually indicating no infection.

Note:

A false result may occur if the biopsy is taken from a non-infected area.

Important Notes When Interpreting Results

A positive result means treatment is necessary:
Treatment usually includes antibiotics and acid-reducing medications for 2–3 weeks, depending on the medical protocol.
A negative result does not always rule out infection:
Recent use of acid-reducing drugs, antibiotics, or bismuth may lead to false results.
Post-treatment follow-up:
Doctors recommend repeating the breath test or stool test after 4–6 weeks to confirm eradication.
The test does not always detect complications:
Conditions such as ulcers or chronic gastritis may require endoscopy or biopsy for accurate evaluation.

How to Read an H. pylori Blood Test Result

The blood test detects antibodies against H. pylori, indicating exposure at some point.

1️⃣ Positive Result

What does it mean?

Antibodies are present, indicating current or past exposure.

What’s next?

The doctor may request a breath or stool test to confirm active infection before treatment.

2️⃣ Negative Result

What does it mean?

No antibodies detected, usually meaning no exposure.
Very recent infections may not yet show antibodies.

What’s next?

If symptoms persist, additional tests may be recommended.

3️⃣ Important Points

The blood test cannot distinguish between past and current infection.
Results may be affected by medications or certain medical conditions.

How to Read H. pylori Test Results by Numbers

1️⃣ Blood Test (Serology)

Negative: Antibody level below the lab cut-off (commonly <1 IU/mL).
Positive: Antibody level above the cut-off (commonly >1 IU/mL).
Note: Cannot confirm active infection.

2️⃣ Stool Antigen Test

Negative: Antigen level below the reference range.
Positive: Antigen level above the reference range, indicating active infection.

3️⃣ Urea Breath Test

Negative: Carbon dioxide level below the cut-off (often <2–3 ppm).
Positive: Carbon dioxide level above the cut-off, indicating active infection.

4️⃣ Endoscopic Biopsy

Negative: No bacteria detected on microscopy or rapid urease test.
Positive: Bacteria detected, confirming infection.

Next Steps After Testing

Positive result with symptoms:
Breath or stool test may be used to confirm active infection before treatment.
Negative result with persistent symptoms:
Endoscopy or biopsy may be required in selected cases.

Conditions for Stool Antigen Testing

1️⃣ Preparation Before the Test

Stop antibiotics: At least 4–6 weeks before testing.
Stop proton pump inhibitors (PPIs): Such as omeprazole or pantoprazole, 2 weeks before testing.
Avoid bismuth medications: For several days before testing.
Fasting: Usually not required unless specified by the lab.