String Test for Giardiasis

For this test, you swallow a gelatin capsule attached to a long string. The end of the string remains outside the mouth and is taped to your cheek. The capsule dissolves in the stomach and the string passes into the upper part of the small intestine (Reference duodenum Opens New Window).

The string is left in place for 4 to 6 hours or overnight. Then it is withdrawn and the end is examined under the microscope for parasites that are attached to it.

This test is also called the Enterotest.

The string test may be done if other methods (especially examination of stool samples and antigen tests) have failed to detect Reference giardiasis Opens New Window.

This test is rarely done. If a small sample of the small intestine is needed to confirm the diagnosis, Reference endoscopy is usually done.

Findings of the string test may include the following.

Normal

No Giardia parasites are seen when the string is examined.

Abnormal

Giardia parasites can be seen when the string is examined under a microscope.

This test requires you to commit most of a day to the testing procedure. If the string is removed too soon, it may not have had time to reach the small intestine, and the results may be inaccurate. But the test is relatively inexpensive and accurate when done properly.

Complete the medical test information form (PDF) (What is a Reference PDF Opens New Window document?) to help you prepare for this test.

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