Direct Smear Fecal Exam
- Place a small amount of feces on a microscope slide.
- Add a drop of liquid to the feces and mix thoroughly.
The type of liquid added depends on what you hope to accomplish with the
technique. If you are examining a liquid fecal sample for the presence of
protozoan trophozoites (live active protozoa) then use saline (if any extra
liquid is needed).If you are looking for helminth eggs and protozoan
cysts in a small sample (bird droppings, rectal smear, etc) then either water or
iodine may be used.
- Cover with a cover slip. Move the cover slip around
until it lays flat. You should be able to read through the smear (light
from the microscope must be able to pass through the sample in order for you to
examine it).
- Examine the slide using the 10X objective, and then go over
it with the 40X objective.
NOTE: Because this technique examines only a very small amount of
feces, it should only be used in the following circumstances:
- Liquid feces where protozoan trophozoites may be present.*
- Fecal samples where the amount of feces obtained is too
small to handle with any other technique.*
- As an adjunct to a flotation technique where you are
looking for eggs that do not float. (In this case you probably would be better
off running an ethyl acetate sedimentation and examining the resultant pellet
using the direct smear method.)
*These circumstances occur frequently when dealing with small fish, birds, amphibians and reptiles and, thus, the direct
smear has some utility in dealing with fecal samples from these animals. |
