String test for giardiasis
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 Then it is withdrawn and the end is examined under the microscope for parasites that have become attached.
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 it is necessary to sample the contents of the small intestine to confirm the diagnosis, endoscopy is usually done.
Results
Findings of the string test may include the following.
Normal
No parasites are seen when the string is examined.
Abnormal
G. lamblia 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. However, 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
| Author | Colleen Cronin |
| Editor | Susan Van Houten, RN, BSN, MBA |
| Associate Editor | Michele Cronen |
| Associate Editor | Tracy Landauer |
| Primary Medical Reviewer | Adam Husney, MD - Family Medicine |
| Specialist Medical Reviewer | W. David Colby, MSc, MD, FRCPC - Infectious Disease |
| Last Updated | October 19, 2005 |
| Last updated: | October 19, 2005 |
|---|---|
| Author: | Colleen Cronin |
| Reviewed By: | Adam Husney, MD - Family Medicine, W. David Colby, MSc, MD, FRCPC - Infectious Disease |
| Editors: | Susan Van Houten, RN, BSN, MBA, Tracy Landauer |
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