How is the string test performed in the workup of giardiasis?

Updated: Oct 01, 2018
  • Author: Hisham Nazer, MBBCh, FRCP, DTM&H; Chief Editor: Burt Cagir, MD, FACS  more...
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The string test (Entero-test) consists of a gelatin capsule containing a nylon string with a weight attached to it. The patient tapes one end of the string to his or her cheek and swallows the capsule. After the gelatin dissolves in the stomach, the weight carries the string into the duodenum.

The string is left in place for 4-6 hours or overnight while the patient is fasting. After removal, it is examined for bilious staining, which indicates successful passage into the duodenum. The mucus from the string is examined for trophozoites in an iodine or saline wet mount or after fixation and staining.

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