A Stool Analysis for Ova, Cyst & Parasites (often called an O&P stool test) is a laboratory stool test that checks a bowel movement (stool sample) for signs of intestinal parasites and their life stages. The lab looks for:

• Ova (parasite eggs)
• Cysts (a “protected” form some parasites take to survive outside the body)
• Parasites themselves (such as protozoa or worms, depending on the organism)

Many labs also note other findings that may support a diagnosis, such as the presence of blood, excess mucus, or signs of intestinal inflammation. This makes the test helpful when symptoms like diarrhea, abdominal pain, or ongoing abdominal discomfort raise concern for an intestinal infection.

What results can mean:

• Positive (parasites/ova/cysts found): This suggests a parasitic infection. Your clinician may identify the specific parasite and prescribe targeted treatment (often antiparasitic medication). In some cases, additional tests may be recommended to confirm the species or assess severity.
• Negative (none seen): This makes a parasite less likely, but it does not completely rule it out. Parasites may be shed intermittently, and some infections are easier to miss with a single sample. If symptoms persist, your clinician may request repeat stool samples on different days or order other tests (for example, stool antigen/PCR tests) depending on the suspected organism.

This stool test is usually ordered when a healthcare professional wants to find the cause of digestive symptoms or to evaluate possible exposure to parasites. It is especially considered when symptoms are persistent, severe, or associated with certain risk factors.

Common symptoms that may prompt testing include:

• Ongoing or recurrent diarrhea (including watery stools)
• Abdominal pain, cramping, or persistent abdominal discomfort
• Bloating, excess gas, nausea, or poor appetite
• Unexplained weight loss, fatigue, or signs of dehydration
• Visible mucus or blood in stool (your clinician may also order additional stool studies for blood and inflammation)

Risk factors and situations where doctors often order an O&P test:

• Recent travel to areas where parasitic infections are more common
• Exposure to untreated water (streams, lakes) or contaminated food
• Daycare exposure, close-contact settings, or household outbreaks of diarrhea
• Weakened immune system (for example, certain medications or medical conditions), where infections may be more severe or prolonged
• Persistent GI symptoms after suspected “stomach bug,” especially if symptoms last more than several days

The goal is to determine whether parasites are causing symptoms so that treatment can be specific and effective, and to help prevent spread to others when relevant.

• Giardiasis (Giardia infection)
• Amoebiasis (Entamoeba histolytica infection)
• Cryptosporidiosis
• Cyclosporiasis
• Ascariasis (roundworm infection)
• Hookworm infection
• Trichuriasis (whipworm infection)
• Enterobiasis (pinworm infection)
• Strongyloidiasis
• Taeniasis (tapeworm infection)

• Finding the cause of diarrhea and chronic digestive upset
• Evaluating abdominal pain, cramping, or ongoing abdominal discomfort
• Diagnosing and guiding treatment for suspected intestinal parasite infection
• Supporting recovery after travel-related or water/food-borne gastrointestinal illness
• Reducing transmission risk by identifying contagious parasitic infections in households or close-contact settings
• Clarifying next steps when symptoms persist despite initial treatment (deciding whether repeat stool testing or different stool studies are needed)