MedlinePlus Medical Encyclopedia: String test

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String test

Contents of this page:
Illustrations Alternative Names Definition How the Test is Performed How to Prepare for the Test	How the Test Will Feel Why the Test is Performed Normal Results What Abnormal Results Mean Considerations

Illustrations

Ascaris lumbricoides egg

Gelatin capsule in stomach

Alternative Names Return to top

Duodenal parasites test

Definition Return to top

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.

How the Test is Performed Return to top

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 Return to top

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

How the Test Will Feel Return to top

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 Return to top

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

Normal Results Return to top

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

What Abnormal Results Mean Return to top

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

Considerations Return to top

Previous drug treatment can affect the test results.

Update Date: 1/22/2007

Updated 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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