String test for giardiasis

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Exam Overview

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 (duodenum).

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 Then it is withdrawn and the end is examined under the microscope for parasites that are attached to it.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.

Why It Is Done

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

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

Results

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.

What To Think About

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 PDF document?) to help you prepare for this test.

Credits

Last updated:	October 16, 2007
Author:	Maria G. Essig, MS, ELS
Reviewed By:	E. Gregory Thompson, MD - Internal Medicine, W. David Colby IV, MSc, MD, FRCPC - Infectious Disease
Editors:	Susan Van Houten, RN, BSN, MBA, Pat Truman, MATC