The Trichrome technique of Wheatly for fecal specimens is a modification of Gomori's original staining procedure for tissue. It is a rapid, simple procedure, which produces uniformly well-stained smears of the intestinal protozoa, human cells, yeast, and artifact material. Examine the smear microscopically utilizing the 100x objective. Examine at least 200 to 300 oil immersion fields. When the smear is thoroughly fixed and the stain is performed correctly, the cytoplasm of protozoan trophozoites will have a blue green color sometimes with a tinge of purple.
Cysts tend to be slightly more purple.
Glycogen is dissolved by the solvents and appears as a clear area in the organism. The background material usually stains green providing a nice color contrast with the protozoa.