PROVET HEALTHCARE INFORMATION

FAECAL FLOTATION

Description

There are several techniques to detect for the presence of parasites in faeces samples using a method that floats the shed eggs, cysts or oocysts to the top of a solution separating them from the mixture and so making it easier to prepare a slide for examination under a microscope.

Method

At least 5g of fresh faeces are collected into a clean, dry, uncontaminated container (glass or plastic).

Before faecal flotation a direct smear should be taken and examined by low and high power, phase-contrast and/or darkfield microscopy as soon as possible. If a patient has diarrhoea the sample should be examined within 30 minutes of collection otherwise fragile components (e.g. trophozoites from protozoal infections) may be destroyed by refrigeration or other methods of preservation.

The faeces is mixed with the appropriate solution and the mixture left to settle. The eggs or cysts or oocysts float to the top of the mixture and can be identified by microscopic examination of the top layer.

1. Sheather's sugar solution- for helminths, protozoa, Toxoplasma, Cryptosporidium
2. Zinc sulphate centrifugation technique - for protozoa and helminth parasites. It is better for the identification of Giardia cysts (causes less distortion)

Last updated : October 2013