Laboratory Services

Ova and Parasite, Concentrate and Permanent Smear, Microscopy, Feces

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Updated Test Information:

Test Description
Ova and Parasite, Concentrate and Permanent Smear, Microscopy, Feces

O and P (Ova and Parasites); Trichrome Stain; Egg Cyst; Parasitic Exam; Protozoa; Amoeba, Ameba; Ova; 50016-OAP; Helminth; Isospora, Isospora belli, Cystoisospora; Parasites

Test ID
General Information

Useful for:

  • Detection and identification of parasitic protozoa and the eggs and larvae of parasitic helminths

  • Includes concentrated wet preparation and permanent (trichrome) stained preparation as well as an exam for fecal leukocytes

  • Ordering Guidance:

    • See OAPNS (Ova and Parasite, Microscopy, Varies) for the submission of non-stool sources for ova and parasitic examination

    • If specific organisms or disease states are suspected, see below:

    • If Acanthamoeba is suspected, order ACARP (Acanthamoeba species Molecular Detection, PCR, Ocular)

    • If Cryptosporidium is suspected, order CRYPS (Cryptosporidium Antigen, Feces)

    • If Cyclospora is suspected, order CYCL (Cyclospora Stain)

    • If free-living amebae are suspected, order FLARP (Free-Living Amebae Molecular Detection, PCR, Spinal Fluid, Fresh and Paraffin Tissue)

    • If Giardia is suspected, order GIAR (Giardia Antigen, Feces)

    • If microsporidia are suspected, order LCMSP (Microsporidia species, Molecular Detection, PCR)

    • If pinworm is suspected, order PINW (Pinworm Exam, Perianal)

    • If scabies is suspected, order PARID (Parasite Identification)

    • If Schistosoma is suspected, order SHUR (Schistosoma Exam, Urine)

    • If Trichomonas vaginalis is suspected, order TVRNA (Trichomonas vaginalis, Nucleic Acid Amplification, Female Patients, Varies)

    • If worms or worm segments are submitted, order PARID (Parasite Identification)

    • See Parasitic Investigation of Stool Specimens Algorithm

    • See also Laboratory Testing for Infectious Causes of Diarrhea

Specimen Type


Specimen Requirements

ECOFIX vial for parasitic exam

Specimen Collection / Processing Instructions

  • Patient Preparation: Specimen collection should be delayed for 7 to 10 days after administration of barium, bismuth, kaolin, magnesia, castor oil or mineral oil, and 2 to 3 weeks after antibiotics have been given since these may interfere with identification of protozoa

  • Specimen Type: Stool, duodenal aspirate, colonic washing

  • Supplies: ECOFIX Stool Transport Vial (Kit) (T219)

  • Preferred: ECOFIX preservative (T219)

  • Acceptable: 10% Buffered Formalin Stool Transport plus Polyvinyl Acetate (PVA) Stool Transport

  • Specimen Volume: Portion of stool; or entire collection of intestinal specimen

  • Collection Instructions:

    • Place specimen into preservative within 30 minutes of passage or collection

    • Follow instructions on the container as follows:

      • Mix the contents of the tube with the spoon, twist the cap tightly closed, and shake vigorously until the contents are well mixed. Refer to the fill line on the Ecofix vial for stool specimens

      • Do not fill above the line indicated on the container

      • Duodenal aspirates, small bowel aspirates, or colonic washings should be placed in Ecofix in a ratio of 1:1

  • Additional Information: Stool placed in 10% buffered formalin can be accepted if accompanied by a PVA-preserved specimen; 10% buffered formalin-preserved specimens submitted without an accompanying PVA-preserved specimen will be canceled.


  • Ambient (preferred): 21 days

  • Refrigerated: 21 days

Unacceptable Specimen Conditions

All specimens will be evaluated by Mayo Clinic Laboratories for test suitability.


  • It is strongly recommended that multiple stool specimens be submitted for ova and parasite analysis. At least 3 specimens should be collected, 1 each day or on alternate days (over a maximum 10-day period)

  • Parasites are shed irregularly in stool and examination of a single specimen does not guarantee detection

  • If possible adult worms or proglottids are identified in stool or the patient undergarments, they should be placed in 70% alcohol and submitted for PARID / Parasite Identification

  • For optimal results, the specific test should be ordered for detection of Giardia, Cryptosporidium, microsporidia, Cyclospora, or pinworm. The OAP / Parasitic Examination is not the optimal method for detecting these parasites

  • Parasitic examination of a minimum of 3 stool specimens is indicated for detecting most intestinal protozoa and helminths with maximum sensitivity

  • Parasitic infections are uncommonly acquired in the hospital setting. This test is not usually useful in patients hospitalized for more than 3 days



Estimated TAT

2-4 days

Testing Schedule



7 days

CPT Code(s)

87177; 87209

Additional Information
Minimum Sample Volume

5 mL

Reference Range


Performing Lab


LOINC Code(s)