String Test (Entero-test): Purpose, Procedure and Results

What Is a String Test?

A string test, also known as “entero-test,” is a type of test allowing the detection of parasites in the upper part of the small intestine. Once established, These parasites may develop and flourish at your expense.

An abnormal result may indicate that you have Giardia intestinalis or some other parasite in your body. The following symptoms may occur as a result of parasites:

  • nausea
  • vomiting
  • diarrhea
  • upset stomach
  • other gastrointestinal (Gl)conditions.

What Causes Intestinal Parasites?

Intestinal parasites spread when tiny pieces of fecal matter enter your mouth. They can be contracted like this:

  • ingesting food or water contamination, such as:
    • ingesting contaminated water from pools, lakes, rivers, ponds or creeks.
    • accidentally swallow anything that comes in contact with a person’s or animal’s stool.
    • eating unpacked contaminated food.
    • contact surfaces that may be contaminated by the feces of an infected person, such as toys, bathroom fixtures, changing tables, or diaper pails, and touching each other’s eyes or mouth, or using utensils to eat whatever you touched.
    • visit foreign countries where parasites are most prevalent.
  • changing a diaper
  • when having sexual intercourse, either orally or anal.

Types of Intestinal Parasites


Protozoa are single-celled organisms, including Giardia intestinalis, that may be present in your intestines and may cause the conditions and symptoms include:

  • fatigue
  • nutritional disorders
  • dizziness
  • joint pain
  • hives
  • chronic diarrhea

Common types of protozoan parasites may cause a number of diseases, including amibiasis, giardiase and cryptosporidiosis.


This condition occurs because of the parasite Entamoeba histolytica. Symptoms include: (1)

  • stomach cramps
  • diarrhea
  • fever

Amoebiasis is most commonly found in areas where sanitation is poor. You can arrange for him to travel to developing countries.


This condition is caused due to parasite Giardia intestinalis, the most commonly occurring parasites in the developed world.


This condition occurs as a result of a parasite Cryptosporidium (1). This parasite has become increasingly widespread in both developed and developing countries., in persons who have weakened immune systems, for example:

  • persons suffering from AIDS.
  • transplant recipients
  • small children under 5 years of age.


Helminths are small parasitic which may attach to the lining of the small intestine, resulting in bleeding and loss of nutrients. They tend to thrive in developing regions of the world where adequate water and sanitation facilities are not available.

Helminths include:

  • tapeworms
  • flatworms
  • roundworms

Areas of the world with the most common helminths include:

  • Asia
  • Africa
  • Latin America

Who Might Need a String Test?

If you suffer from stomach pain, including diarrhea and vomiting, and you have also been camping, travelled abroad or taken part in other activities that expose you to the risk of acquiring intestinal parasites, your doctor may provide tests for the elimination of parasites. In the USA, the first test is generally a stool sample. You may need to collect one or more samples from home that will be tested for parasites in the laboratory.

If your stool samples return negative and you are still symptomatic of a parasitic infection, your physician may order the string test. Doctors usually order a rope test when they think you can have giardiasis or other superior intestinal parasites.

What Happens During a String Test?

The string test, or entero-test, is used to extract material samples from the early part of your small intestine, right behind the stomach. These samples are examined with a microscope to determine if parasites are present.

Before the test, you may be required to refrain from eating or drinking for a maximum of 12 hours. To test, you will swallow a gelatin capsule, much like a vitamin supplement. This capsule consists of a spool of nylon thread and a weight to help it get down into the stomach. The end of the string is generally taped to your cheek or back of your neck just prior to swallowing the capsule.

Once the tablet is lowered, your doctor will probably advise you to sit back and relax for about four hours. Children often go to bed during this part of the examination. As you rest, your natural digestive processes will slowly dissolve and move the capsule downwards through your stomach, unraveling the spool of string as it goes. Meanwhile, the string brings together stomach and upper intestinal materials, including potential parasites.

After the specified duration, the rope will be pulled upwards from your stomach through your throat, put into a secure container and transported to the laboratory for examination within one hour.

Are There Any Potential Complications with the Test?

The string test is highly reliable and complications are rare. However, it can be a little awkward because the capsule has a rope tied to it. This may sound strange, or you may experience difficulty swallowing the capsule.

Plus, when the twine is pulled up, you can feel your “gag” reflex or feel like you want to throw up. However, the string is very small and thin and will not do you any harm as it comes. The doctor will probably remove the rope quickly, which means those strange feelings won’t last long. On rare occasions, a minor superficial injury caused by string recovery can lead to bleeding.

What Do the Test Results Mean?

A positive test will show the type and presence of intestinal parasites, helping physicians determine the type of treatment that best suits you. If the test does not reveal any abnormalities, your gastric malaise and other symptoms will probably not be caused by intestinal parasites.

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