Fecal Parasite Examination - The Formol-Ether Concentration

This six minute video presents the Formol-Ether Concentration Technique used to examine fecal parasites. This resource was developed by Charles Adjei Osei of the Kwame Nkrumah University of Science and Technology and Cary Engleberg of the University of Michigan. It is part of a larger learning module about laboratory methods for clinical microbiology. The full learning module, editable animation, and video transcript are available at http://open.umich.edu/education/med/oernetwork/med/microbiology/clinical-microbio-lab/2009. Copyright 2009-2010, Kwame Nkrumah University of Science and Technology and Cary Engleberg. This is licensed under a Creative Commons Attribution Noncommercial 3.0 License http://creativecommons.org/licenses/by-nc/3.0/. Video transcribed by Andrea Matsumoto (University of Michigan).

(English captions by Andrea Matsumoto, University of Michigan.)

These are the items we require in the stool
concentration technique.

We need the stool sample, the fine mesh of
pore size three fifty to four fifteen micrometer,

the fifteen mL centrifuge tube, a glass applicator
for emulsifying the stool sample, the beaker

for the filtrates, the ten percent Formol-saline
for mixing the stool, then the diethyl ether.

Add ten percent Formol-saline to the stool,
about a gram of the stool sample.

Emulsify the stool sample with the applicator.

Emulsify it very well to get a smooth substance.

Sift the stool sample through the fine mesh
into the beaker.

Discard the stool sample.

The debris is discarded under the tap water
because it has been disinfected already with

the Formol.

Transfer seven mils of stool filtrate into
the fifteen mil centrifuge tube.

Rinse whatever is left in the beaker into
the centrifuge tube.

Add three mils of the diethyl ether to the
seven mil of the stool filtrate in the fifteen

mil centrifuge tube making it to a total of
ten mL.

And we will see two layers: the ether layer
and then the Formol-saline layer.

Cover the centrifuge tube with a lid and mix
the two layers very well.

And thus the ether is to dissolve in the fat,
which is present in the stool sample, to release

the parasites.

Put it in the centrifuge tube balancing it.

Centrifuge at thousand five hundred (1500) RPM for
two to five minutes.

Okay take out the centrifuge tube and you
will see four layers.

The first layer is the ether layer, the debris
layer, which is the insoluble pad, and then

Formol-saline layer, and then the sediment
which contains the parasite.

Break through the debris layer and discard
the first three layers under the tap water,

which have already been treated with Formol.

So the sediment will contain the parasites
of the egg or the larvae and then cysts were

suspended with part of the Formol-saline or
saline.

Use a disposable pipet to transmit it very
well and transfer a drop onto the microscope

slide.

Cover the drop of smear with the cover slip
and examine it under the microscope using

the times ten objective (10X).

Low light allows better to see the parasite
of the egg, the cyst, and the larvae.