Stool O and P Test

Overview :

Examination of the stool for ova and parasites is done to diagnose parasitic infection of the intestines. The test may be done in the doctor's office or a laboratory. The patient collects a stool sample in one or more sterile containers containing special chemical fixatives. The feces should be collected directly into the container. It must not be contaminated with urine, water, or other materials. Three specimens are often needed-collected every other day, or every third day. However, as many as six specimens may be needed to diagnose the amoeba Entamoeba histolytica. The specimen does not need to be refrigerated. It should be delivered to the doctor's office or laboratory within 12 hours.

In the laboratory, the stool sample is observed for signs of parasites and their eggs. Some parasites are large enough to be seen without a microscope. For others, microscope slides are prepared with fresh unstained stool, and with stool dyed with special stains. These preparations are observed with a microscope for the presence of parasites or their eggs.

An unstained stool examination for ova and parasites normally only takes a few minutes. If specimen staining and other preparation is done, the test may take longer. When the specimen is sent to a laboratory, the results may take eight to 24 hours to be reported.

The most common intestinal parasites in North America that cause infections are:

• roundworms: Ascaris lumbricoides
• hookworms: Necator americanus
• pinworms: Enterobius follicularis
• tapeworms: Diphyllobothrium latum, Taenia saginata, and Taenia solium
• protozoa: Entamoeba histolytica (an amoeba), and Giardia lamblia (a flagellate)

Numerous other parasites are found in other parts of the world. These may be contracted by travelers to other countries. Patients with acquired immune deficiency syndrome (AIDS) or other immune system disorders are commonly infected with the parasites in the Microsporidia family, Cryptosporidium, and Isospora belli.

Insurance coverage for stool ova and parasites may vary among different insurance plans. This test usually is covered if ordered by a physician approved by the patient's insurance plan, and if it is done at an approved laboratory.