Health Guide

PCR test for Helicobacter pylori

What is this test?

This test detects a bacteria Helicobacter pylori (H. pylori) using a special technique called polymerase chain reaction (PCR). PCR detects gene sequences in bacterial DNA[1]. This test is used when an infection with H. pylori is suspected[2][3][1]. A sample of saliva[3], stool[4], or stomach lining cells through gastric endoscopy[1] may be collected for this test. If you are having a gastric endoscopy, this test may be performed during your endoscopy. However, an endoscopy is generally not performed just to collect a sample for this test.

Why do I need this test?

Laboratory tests may be done for many reasons. Tests are performed for routine health screenings or if a disease or toxicity is suspected. Lab tests may be used to determine if a medical condition is improving or worsening. Lab tests may also be used to measure the success or failure of a medication or treatment plan. Lab tests may be ordered for professional or legal reasons. The following is a possible reason why this test may be done:

  • Helicobacter pylori gastrointestinal tract infection

When and how often should I have this test?

When and how often laboratory tests are done may depend on many factors. The timing of laboratory tests may rely on the results or completion of other tests, procedures, or treatments. Lab tests may be performed immediately in an emergency, or tests may be delayed as a condition is treated or monitored. A test may be suggested or become necessary when certain signs or symptoms appear.

Due to changes in the way your body naturally functions through the course of a day, lab tests may need to be performed at a certain time of day. If you have prepared for a test by changing your food or fluid intake, lab tests may be timed in accordance with those changes. Timing of tests may be based on increased and decreased levels of medications, drugs or other substances in the body.

The age or gender of the person being tested may affect when and how often a lab test is required. Chronic or progressive conditions may need ongoing monitoring through the use of lab tests. Conditions that worsen and improve may also need frequent monitoring. Certain tests may be repeated to obtain a series of results, or tests may need to be repeated to confirm or disprove results. Timing and frequency of lab tests may vary if they are performed for professional or legal reasons.

How should I get ready for the test?


There is no preparation needed for this test.


Before giving a stool sample, tell the healthcare worker if you have diarrhea or are using antibiotics, barium, bismuth, oil, iron, magnesium, or medication to stop diarrhea.

Stomach lining cells:

An endoscopy is a procedure that requires your written consent. Review the consent form with the healthcare worker and ask any questions that you have before signing the consent form. Tell the healthcare worker if you have a history of nosebleeds, throat infections, chest pain, heart conditions, or a recent heart attack. Inform the healthcare worker if you have a medical condition or are using a medication or supplement that causes excessive bleeding. You should also report if you have a history of allergic or other reactions to local anesthetics.

To prepare for an endoscopy, you may be offered a mild sedative prior to the procedure to help you relax. To decrease pain, you will also receive a local anesthetic.

How is the test done?

A sample of saliva, stool, or stomach lining cells through gastric endoscopy may be collected for this test.


Saliva samples may be collected by having you spit into a plastic tube several times or by using a swab. For the swab method you will need to open your mouth wide. The person doing the test will use a long, sterile cotton swab to wipe the inside of your cheeks. The swab may be rubbed several times to collect the sample. Do not close your mouth when the sample is being collected. After the sample has been collected, the swab will be taken out and tested.


For a stool sample, you will be asked to have a bowel movement into a special container. Avoid adding urine, water, tissues, or toilet paper to the stool sample.

Stomach lining cells:

An endoscope is done with conscious sedation through an IV catheter. A local anesthesia will be sprayed into your mouth to prevent you from gagging or coughing when the endoscope is inserted. The endoscope, a flexible fiberoptic instrument that carries a tiny camera, is passed through your mouth. A device called a bite block may be used to protect your teeth. The endoscope then passes through your throat, esophagus (food tube), stomach, and duodenum. Air will be introduced through the endoscope to view the lining of the organs. Samples of cells or tissues may be collected through the endoscope. These samples are then sent to laboratory for testing.

How will the test feel?

The amount of discomfort you feel will depend on many factors, including your sensitivity to pain. Communicate how you are feeling with the person doing the test. Inform the person doing the test if you feel that you cannot continue with the test.


This test usually causes no discomfort.


This test usually causes no discomfort.

Stomach lining cells:

Before the endoscopy, a local anesthesia is sprayed into your mouth. You may feel mild discomfort at the back of your throat. This will make your swallowing difficult. You will also receive medicine called conscious sedation, which puts you in a dream-like state where you should not feel pain or remember the procedure. However, you are still awake enough to move and respond to directions. During the procedure, you may feel mild discomfort when the endoscope enters your mouth. You may also feel the movement of the scope in your abdomen. After the procedure, you may have a sore throat or cough for several days.

What should I do after the test?


There are no special instructions to follow after this test.


After giving a stool sample in a healthcare facility, close the container if it has a lid, and place the container where the healthcare worker instructed. Clean your hands with soap and water. If you have been asked to collect the stool sample while at home, follow the directions provided.

Stomach lining cells:

Following an endoscopy and collection of a sample of cells or tissue, you will need to rest until healthcare workers say that you are able to leave the facility. Your throat may feel sore or dry for a short time. Contact your healthcare worker if you cough up significant amounts of bright red or dark-colored blood, have a high fever, have difficulty swallowing, or have black stools.

What are the risks?

Saliva: Ask the healthcare worker to explain the risks of this test to you before it is performed.

Stool: Giving a stool sample is generally considered safe. Talk to your healthcare worker if you have questions or concerns about this test.

Stomach lining cells: A sample of the stomach lining is collected by a procedure called gastric endoscopy and biopsy. As the endoscope passes through your mouth, there is a risk of damage to your teeth, mouth, and throat. There is also a risk of perforation (hole) in the stomach or bleeding at the biopsy site. If you have a medical condition, or are using a medication or supplement that causes excessive bleeding, you are at a higher risk of bleeding during or after this procedure.

What are normal results for this test?

Laboratory test results may vary depending on your age, gender, health history, the method used for the test, and many other factors. If your results are different from the results suggested below, this may not mean that you have a disease. Contact your healthcare worker if you have any questions. The following is considered to be a normal result for this test:

  • Negative

What follow up should I do after this test?

Ask your healthcare worker how you will be informed of the test results. You may be asked to call for results, schedule an appointment to discuss results, or notified of results by mail. Follow up care varies depending on many factors related to your test. Sometimes there is no follow up after you have been notified of test results. At other times follow up may be suggested or necessary. Some examples of follow up care include changes to medication or treatment plans, referral to a specialist, more or less frequent monitoring, and additional tests or procedures. Talk with your healthcare worker about any concerns or questions you have regarding follow up care or instructions.

Where can I get more information?

Related Companies

  • Centers for Disease Control and Prevention (CDC) -
  • American Academy of Family Physicians -
  • National Digestive Diseases Information Clearinghouse (NDDIC) -


[1] Lage AP, Godfroid E, Fauconnier A, et al: Diagnosis of Helicobacter pylori infection by PCR: comparison with other invasive techniques and detection of cagA gene in gastric biopsy specimens. J Clin Microbiol 1995; 33:2752-2756. Available from URL: As accessed February 11, 2005.

[2] Makristathis A, Pasching E, Schutze K, et al: Detection of helicobacter pylori in stool specimens by PCR and antigen enzyme immunoassay. J Clin Microbiol 1998; 36:2772-2774.

[3] Dunn BE, Cohen H, & Blaser MJ: Helicobacter pylori. Clin Microbiol Rev 1997; 10:720-741. Available from URL: As accessed February 11, 2005.

[4] Bujanover Y, Reif S, & Yahav J: Helicobacter pylori and peptic disease in the pediatric patient. Pediatr Clin North Am 1996; 43(1):213-234.

Last Updated: 6/12/2013
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