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String test

Definition

A string test involves swallowing a string to obtain a sample, which is then tested to detect the presence of intestinal parasites. The string test is rarely performed in the U.S.

Alternative Names

Duodenal parasites test

How the test is performed

You swallow a string with a weighted gelatin capsule on the end and then it is pulled back out after 4 hours. Any bile, blood, or mucus attached to the string is examined under the microscope for cell types and parts of parasites or eggs.

How to prepare for the test

Food and fluid may be restricted for 12 hours before the test.

How the test will feel

You may find it difficult to swallow the string, and you may feel an urge to vomit when the string is pulled up.

Why the test is performed

The test is performed when there is a suspicion of parasitic infestation but parasites are not detected by stool examination.

Normal Values

No presence of blood, parasites, fungus, abnormal cells, or bile is normal.

What abnormal results mean

Abnormal results may indicate the presence of giardia or another parasitic infestation.

Special considerations

Previous drug treatment can affect the test results.

Review Date:1/22/2007
Reviewed By:Jenifer K. Lehrer, MD, Department of Gastroenterology, Frankford-Torresdale Hospital, Jefferson Health System, Philadelphia, PA. Review provided by VeriMed Healthcare Network.

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