The Entero-Test, also known as a duodenal capsule or string test, retrieves parasites that inhabit the duodenal area. The patient swallows a gelatin capsule surrounding the end of a string; the other end is taped to the cheek. The capsule dissolves, and the string continues via peristalsis into the duodenum. After about 4 hours, the string is retrieved, and the mucous at the end of it is examined for parasites. Either a direct wet mount or a permanent stained smear can be made. This technique is ideal for finding Giardia sp. and some coccidian parasites.
An example of a parasite that can be retrieved by this method is shown in the image to the right, which shows a wet mount of an immature oocyst of coccidian parasite known as Cystoisospora belli (Isospora belli).
