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.
How the Test is Performed
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.
How to Prepare for the Test
You may be asked not to eat or drink anything for 12 hours before the test.
How the Test will Feel
You may find it hard to swallow the string. You may have an urge to vomit when the string is being removed.
Why the Test is Performed
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.
What Abnormal Results Mean
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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Update Date 5/15/2014
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.