Stool for Ova and Parasite (O&P) test




1. Objective

The objective of the Stool for Ova and Parasite (O&P) test was to detect the presence of parasitic organisms, including protozoa (trophozoites and cysts) and helminths (eggs and larvae), in the fecal specimen of a patient with gastrointestinal symptoms.

2. Principle

The test was based on the microscopic identification of parasite ova (eggs), cysts, and trophozoites in concentrated or direct wet mount stool preparations. Concentration techniques improved detection by separating parasites from fecal debris. Iodine and saline were used to enhance visibility.

3. Materials

  • Stool collection container

  • Applicator sticks

  • Glass slides and cover slips

  • Normal saline (0.85%)

  • Iodine solution (e.g., Lugol’s iodine)

  • Centrifuge tubes (if using concentration method)

  • Formalin or preservative (for preserved samples)

  • Microscope

  • Gloves

  • Biohazard disposal materials

4. Procedure (Microscopic – Direct Wet Mount Method)

  • A small amount of freshly passed stool was collected with an applicator stick.

  • Two wet mount slides were prepared: one with normal saline, and one with Lugol’s iodine.

  • The stool was mixed with the solutions on separate slides and covered with cover slips.

  • Each slide was examined under low (10x) and high power (40x) objectives.

  • Motile trophozoites, cysts, and ova of helminths were identified and documented.

  • In some cases, concentration by sedimentation or flotation was performed prior to microscopic observation.

5. Result

  • Positive: Identified and reported parasites such as Giardia lamblia, Entamoeba histolytica, Ascaris lumbricoides, Trichuris trichiura, or Hookworm ova.

  • Negative: No ova, cysts, or parasites were detected in the sample.

Example report:

Cysts of Entamoeba histolytica and ova of Ascaris lumbricoides were detected in saline preparation. No trophozoites observed.

6. Uses

The O&P test was used to:

  • Diagnose parasitic infections causing diarrhea, abdominal pain, or dysentery

  • Monitor treatment response in confirmed parasitic infections

  • Screen individuals in endemic areas or travelers returning from tropical regions

7. Consultation

Upon completion of the test, a healthcare provider reviewed the findings with the patient. If parasites were identified, specific anti-parasitic treatment was prescribed, and hygiene measures were advised to prevent reinfection. Additional testing (e.g., repeat samples, antigen tests) was sometimes recommended to confirm eradication.

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