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Ova and Parasites (Stool)

Does this test have other names?

Stool sample exam, stool O&P, fecal smear

What is this test?

This test looks for parasites and their larvae or eggs (ova) in a sample of your stool.

Parasites are organisms that can live within or on the human body and use it as a source of food. Many live in the digestive tract.

Many parasites also cause illnesses. These include one-celled organisms, such as Giardia, and larger organisms, such as pinworms. In their adult form, pinworms are usually large enough to be seen.

Why do I need this test?

You may need this test if your healthcare provider suspects that you have parasites in your digestive tract. Giardia and cryptosporidium are common parasitic illnesses. Symptoms include:

  • Stomach upset, nausea, or bloating

  • Diarrhea

  • Greasy stools that can float

  • Gas

  • Stomach cramping

  • Dehydration

  • Weight loss

Pinworms can live in the colon and rectum. Anal itching is a symptom of a pinworm infection. The itching is usually worse at night and may disturb your sleep.

What other tests might I have along with this test?

You may also need blood tests and other tests for specific parasites. For example, if your healthcare provider thinks you may have a pinworm infection, you may have to do a "tape test." In this test, the adhesive side of a piece of cellophane tape is gently pressed to the skin around the anus. Pinworm eggs will stick to the tape. Then the eggs can be moved to a slide and looked at under a microscope.

What do my test results mean?

Test results may vary depending on your age, gender, health history, and other things. Your test results may be different depending on the lab used. They may not mean you have a problem. Ask your healthcare provider what your test results mean for you.

Normal results are negative, meaning that no parasites, larvae, or eggs were found in your sample.

Positive results mean that you have an infection with a parasite.

How is this test done?

This test is done with a stool sample. Your healthcare provider will tell you how to collect the sample and how many samples are needed. Don't collect fecal material from the toilet bowl or put toilet paper into the specimen container.

What might affect my test results?

Certain medicines can affect your results. This can be true for up to 1 week after you take the medicines. These medicines include:

  • Antacids

  • Bismuth

  • Some medicines used to treat diarrhea

  • Barium

  • Antibiotics

  • Oily laxatives

A sample contaminated by urine or toilet water may have an inaccurate result. Timing is also important. If the sample isn't brought to the lab promptly, the results may not be accurate.

How do I get ready for this test?

You may need to stop taking certain medicines before the test. Be sure your healthcare provider knows about all medicines, herbs, vitamins, and supplements you are taking. This includes medicines that don't need a prescription and any illegal drugs you may use.

Online Medical Reviewer: Chad Haldeman-Englert MD
Online Medical Reviewer: Raymond Turley Jr PA-C
Online Medical Reviewer: Tara Novick BSN MSN
Date Last Reviewed: 9/1/2022
© 2000-2024 The StayWell Company, LLC. All rights reserved. This information is not intended as a substitute for professional medical care. Always follow your healthcare professional's instructions.
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