Search

String test

Definition

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.

Alternative Names

Duodenal parasites test

How the test is performed

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.

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 difficult to swallow the string, and you may feel 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.

Normal Values

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.

What the risks are

Special considerations

Treatment with certain drugs can affect the test results.

References

DuPont HL. Approach to the patient with suspected enteric infection. In: Goldman L, Schafer AI, eds. . 24th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 291.

Semrad CE. Approach to the patient with diarrhea and malabsorption. In: Goldman L, Schafer AI, eds. . 24th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 142.

Giannella RA. Infectious enteritis and proctocolitis and bacterial food poisoning. In: Feldman M, Friedman LS, Brandt LJ, eds. . 9th ed. Philadelphia, Pa: Saunders Elsevier; 2010:chap 107.

Croft AC, Woods GL. Specimen collection and handling for diagnosis of infectious diseases. In: McPherson RA, Pincus MR, eds. . 22nd ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 63.

Salwen MJ, Siddiqi HA, Gress FG, Bowne WB. Laboratory diagnosis of gastrintestinal and pancreatic disorders. In: McPherson RA, Pincus MR, eds. . 22nd ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 22.

Fritsche TR, Selvarangan R. Medical parasitology. In: McPherson RA, Pincus MR, eds. . 22nd ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 62.

Encyclopedia content is provided as information only and not intended to replace the advice and instruction from your personal physician.