Stool Test: Ova and Parasites (O&P)

What It Is

A stool (feces) sample can provide valuable information about problems in the stomach, intestines, rectum, or other parts of the gastrointestinal (GI) system.

In an ova and parasites (O&P) exam, a technician views a sample of stool under a microscope to look for parasites and their ova (eggs) or cysts, which are hard shells that protect some parasites at a certain stage in their lifecycle.

Why It's Done

A doctor may request an O&P exam if your child has symptoms of a possible parasitic infection, such as diarrhea for an extended period of time, blood or mucus in the stool, abdominal pain, nausea, headaches, or fever, especially if there's been an outbreak of parasitic illness at your child's school or daycare center, your child recently drank untreated water, or if your family recently visited a developing country.

Preparation

Unlike most other lab tests, a stool sample is often collected by parents at home, not by health care professionals at a hospital or clinic.

If possible, your child may be asked to avoid certain foods and treatments for 2 weeks before the test, including:

antacids, antidiarrheal drugs, and laxatives
antibiotics and antiparasite drugs
enemas
contrast materials (liquids taken before some X-rays, CAT or CT scans, or other imaging studies)

Procedure

The doctor or hospital laboratory will usually provide written instructions on how to collect a stool sample. If instructions aren't provided, here are tips for collecting a stool sample from your child:

Be sure to wear latex gloves and wash your hands and your child's hands afterward.
Many kids with diarrhea, especially young kids, can't always let a parent know in advance when a bowel movement is coming. So a hat-shaped plastic lid is used to collect the stool specimen. This catching device can be quickly placed over a toilet bowl, or under your child's bottom, to collect the sample. Using a catching device can prevent contamination of the stool by water and dirt. Another way to collect a stool sample is to loosely place plastic wrap over the seat of the toilet. Then place the stool sample in a clean, sealable container before taking it to the lab.
Plastic wrap can also be used to line the diaper of an infant or toddler who isn't yet using the toilet. The wrap should be placed so that urine runs into the diaper, not the wrap.
Your child shouldn't urinate into the container and, if possible, should empty his or her bladder before a bowel movement so the stool sample isn't diluted by urine.
The stool should be collected into a clean, dry plastic jar with a screw-cap lid. For best results, the stool should be brought to the lab right away. If this isn't possible, the stool should be stored in preservative provided by the lab and then taken there as soon as possible.

What to Expect

When the sample arrives at the laboratory, a technician stains some of the stool specimen with a special dye and views it under a microscope to identify parasites or ova that are present.

Getting the Results

In general, the result of the ova and parasites test are reported within 2 days.

Risks

No risks are associated with collecting stool samples.

Helping Your Child

Collecting a stool sample is painless. Tell your child that collecting the stool won't hurt, but it has to be done carefully. A child who's old enough might be able to collect the sample alone to avoid embarrassment. Tell your child how to do this properly.