A microscopic exam can be performed once the stool specimen has been received and properly processed. The exam can be of three types: a direct wet mount, an indirect wet mount, or a permanent stained smear. Here are some notes and tips on each:
Direct Wet Mount (in saline or Lugols/D'Antoni's iodine)
- Low power - examine the entire 22mm × 22mm coverslip area
- High dry - examine one-third to one-half 22mm × 22mm coverslip area
- The direct wet mount is not part of routine O&Ps unless requested on a very fresh specimen
Indirect Wet Mount
- Performed after a concentration technique (flotation or sedimentation) yields protozoan cysts, coccidian oocysts, micrococcidia spores, and helminth eggs
- Low power - examine the entire 22mm × 22mm coverslip area
- High dry - examine one-third to one-half 22mm × 22mm coverslip area
Permanent Stained Smear
- Most important part of the microscopic exam
- Examples of stains: Trichrome, Iron-hematoxylin, acid-fast stain for coccidia. The image to the right shows a trichrome-stained smear of Dientamoeba fragilis. Trichrome is the most commonly used stain for permanent smears.
- Examine oil immersion, approximately 300 oil immersion fields recommended
