Ova and Parasite (O&P) Examinations

Microscopic Examination - Ova and Parasite Examination

Topic		Comments
Principle		To assess worm burden of patient, to provide quick diagnosis of heavily infected specimen, to check trophozite motility and to diagnose organisms that might not seen from concentration or permanent stain methods (very rare).
Specimen		Any fresh stool specimen that has not been refrigerated.
Reagents		0.85% NaCl; Lugol's or D'Antoni's iodine.
Examination		Low power examination (100X) of entire 22 x 22 coverslip preparation (both saline and iodine); high dry power examination (400X) of at least 1/3 of the coverslip area (both saline and iodine).
Results and Laboratory Reports		Often results from the direct smear examination should be considered presumptive; however, some organisms could be definitely identified (Giardia lamblia cysts and Entamoeba coli cysts, helminth eggs and larvae, Isospora belli oocysts). These reports should be categorized as "preliminary" while the final report would be available after the results of the concentration and permanent stained smear were available.
Procedure Notes and Limitations		Once iodine is added to the preparation, the organisms will be killed and motility lost. Specimens that arrive in the laboratory already preserved do not require a direct smear examination; proceed to the concentration and permanent stained smear. Direct smears are normally examined at low (100X) and high dry power (400X); oil immersion examination (1000X) is not recommended (organism morphology not that clear).