Images

Read More

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 detect the presence of intestinal parasites. The string test is rarely used in the United States.

You swallow a string with a weighted gelatin capsule on the end. Four hours later it is pulled back out. Any bile, blood, or mucus attached to the string is examined under the microscope 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 difficult to swallow the string, and you may feel an urge to vomit when the string is being removed.

The test is performed when the doctor suspects a parasite infection, but no parasites were found in a stool sample.

No presence of blood, parasites, fungus, or abnormal cells is normal.

Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.

Abnormal results may indicate the presence of giardia or another parasitic infestation.

Previous drug treatment can affect the test results.

Duodenal parasites test

Sears CL. Giardiasis. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007: chap 372.

Updated by: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine; George F. Longstreth, MD, Department of Gastroenterology, Kaiser Permanente Medical Care Program, San Diego, CA. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.