A string test involves swallowing a string to obtain a sample from the upper part of the small intestine. The sample is then tested to look for intestinal parasites. The string test is rarely used in the United States.
To have this test, you swallow a string with a weighted gelatin capsule on the end. The string is pulled out 4 hours later. Any bile, blood, or mucus attached to the string is examined under the microscope to look for cells and parasites or parasite eggs.
You may be asked not to eat or drink anything for 12 hours before the test.
You may find it hard to swallow the string. You may have an urge to vomit when the string is being removed.
The test is performed when your health care provider suspects that you have a parasite infection, but no parasites were found in a stool sample.
No blood, parasites, fungi, or abnormal cells is normal.
Normal value ranges may vary slightly among different laboratories. Talk to your health care provider about the meaning of your specific test results.
Abnormal results may be a sign of giardia or another parasite infection.
Treatment with certain drugs can affect the test results.
Duodenal parasites test
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Updated by: Jenifer K. Lehrer, MD, Department of Gastroenterology, Frankford-Torresdale Hospital, Aria Health System, Philadelphia, PA. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.
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