String test: MedlinePlus Medical Encyclopedia

P 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.

T How the Test is Performed
P 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. This is done to look for cells and parasites or parasite eggs.

T How to Prepare for the Test
P You may be asked not to eat or drink anything for 12 hours before the test.

T How the Test will Feel
P You may find it hard to swallow the string. You may have an urge to vomit when the string is being removed.

T Why the Test is Performed
P The test is performed when your health care provider suspects that you have a parasite infection. Usually a stool sample is tested first. A string test is done if the stool sample is negative.

T Normal Results
P No blood, parasites, fungi, or abnormal cells is normal.
P Normal value ranges may vary slightly among different laboratories. Talk to your provider about the meaning of your test results.

T What Abnormal Results Mean
P Abnormal results may be a sign parasite infection such as giardia.

T Considerations
P Treatment with certain drugs can affect the test results.

T Alternative Names
P Duodenal parasites test; Giardia - string test

T Images
- Ascaris lumbricoides egg
- Gelatin capsule in stomach

T References
P Beavis, KG, Charnot-Katsikas, A. Specimen collection and handling for diagnosis of infectious diseases. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 23rd ed. Philadelphia, PA: Elsevier; 2017:chap 64.
P Bope ET, Kellerman RD. The infectious diseases. In: Bope ET, ed. Conn's Current Therapy 2016. Philadelphia, PA: Elsevier; 2016:chap 3.
P Haines CF, Sears CL. Infectious enteritis and proctocolitis. In: Feldman M, Friedman LS, Brandt LJ, eds. Sleisenger and Fordtran's Gastrointestinal and Liver Disease. 10th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 110.
P Hall GS, Woods GL. Medical bacteriology. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 23rd ed. Philadelphia, PA: Elsevier; 2017:chap 58.
P Hill DR, Nash TE. Giardia lamblia. In: Bennett JE, Dolin R, Blaser MJ, eds. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases. 8th ed. Philadelphia, PA: Elsevier Saunders; 2015:chap 281
P Siddiqi HA, Salwen MJ, Shaikh MF. Laboratory diagnosis of gastrintestinal and pancreatic disorders. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 23rd ed. Philadelphia, PA: Elsevier; 2017:chap 22.

T Review Date 5/11/2016
P Updated by: Subodh K. Lal, MD, gastroenterologist with Gastrointestinal Specialists of Georgia, Austell, GA. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.

