Faecal Examination - Practical Task

Arlo Guthrie — Mon, 20 Apr 2009 13:04:50 GMT

Current Revision posted to Revision Guide For Student Nurses - Part 2 by Arlo Guthrie on 4/20/2009 1:04:50 PM

INTRODUCTION
The microscopic examination of faeces can be very helpful in the identification of helminths, protozoa and undigested foodstuffs.
There are 2 basic methods:

Direct wet preparation.
Faecal sedimenation.

As with all laboratory tests, ensure that protective clothing is worn, long hair tied back out of the way and any jewellery removed.
Always check the microscope for safety prior to use, paying particular attention to the plug and electrical cable. Ensure that it is situated on a flat, clean, dry surface.

Direct Wet Preparation:

Place 1 drop of saline onto a microscope slide.
Add an equal amount of fresh faeces.
Add stain as necessary if looking for undigested food stuffs:
- Lugol's iodine = stains starch granules blue-black.
- New methylene blue = stains undigested meat fibres.
- Sudan III = stains faecal fat orange.
Thoroughly mix the sample.
Transfer a small drop by pipette to a clean labelled slide.
Make a thin smear and place a cover slip over the slide.
Transfer the slide to the stage of the microscope and examine under low power for worm eggs and undigested food stuffs.
Use medium power to look for protozoa, or flame fix the slide for examination under oil immersion.

Faecal Sedimentation

Place 2g of fresh faeces into a screw-top glass jar.
Add a small amount of tap water, replace the cap, agitate and strain.
Half fill a centrifuge tube with the strained fluid.
Spin at 1500rpm for 5 minutes.
Pour off the supernatant.
Transfer a small amount of sediment to a labelled microscope slide with a Pasteur pipette.
Add a stain as for direct wet preparations if looking for undigested foodstuffs.
Place a cover slip over the slide.
Transfer the slide to the stage of the microscope and examine under low power for worm eggs and undigested foodstuffs.