Quick Review Cards for Medical Laboratory Science

Ova and Parasite Examination Clinical Microbiology Review 235

Number of specimens

Interfering substances

Preservation

Direct smear, saline

Direct smear, iodine

Concentration

Sedimentation method

Flotation method

Permanent stained slides

1–3

Antibiotics, antiseptics, barium, laxatives, mineral oil, soap, water, urine

Polyvinyl alcohol (PVA), 5%–10% formalin, MIF, sodium acetate–acetic acid–formalin (SAF).

Formed stools may be refrigerated for 1–2 days

On fresh liquid stools. To observe motility of trophs

1% D’Antoni or Lugol’s iodine. To observe nuclei of cysts. Trophs will be killed

To concentrate parasites & separate from fecal debris

Formalin-ethyl acetate. Recovers eggs, larvae, cysts

33% zinc sulfate. Specific gravity 1.18. Parasites float to top. May miss operculated eggs,

unfertilized Ascaris

For Dx of protozoa. PVA fixed or fresh specimen. Iron hematoxylin or trichrome stain