Collection of Stool Specimen
• For stool examination, a fresh specimen is collected in a clean, dry and leak-proof container.
• The
specimen should not be contaminated with urine, so be sure to instruct the
patient correctly.
• The
collection of several specimens on alternate days may be required to detect
parasites.
• Give a
patient a specimen collection container and a spatula and instruct collect to
collect the stool specimen as follows:
o You have
been asked to collect a stool specimen for laboratory analysis.
o Please
wash your hands before beginning the procedure.
DO NOT pass the specimen into the toilet
DO NOT pass the specimen directly into the
collection vial.
DO NOT urinate on the specimen or into the
collection vial.
DO NOT allow any water to mix with the specimen.
o Pass the
stool specimen into any clean and dry container such as a bedpan, plastic plate,
or newspaper.
o Carefully
open a specimen collection container
o Using the
wooden spatula, collect small amounts of stool from areas that are slimy, watery,
or bloody and place them into a specimen collection container.
o If the
stool is hard, collect small amounts from both ends and the middle and place into
a specimen collection container.
o Fill the
specimen collection container with enough specimen (About 1 spoonful or 10ml if
it is a liquid specimen.)
• Obtain a
stool sample (in the container) from a patient. Adhere to infection prevention and
control standards.
• Write
patient’s name, date, & time of collection on the container
• The specimen
must be transported as soon as possible to the lab and must be
accompanied
by a doctors request form.
• Stool
samples must be examined within one hour after collection.
Macroscopic Examination of Stool Specimen
• A
macroscopic examination reports the physical appearance of a specimen. This
includes a description of:
o colour
(yellow, brown or black)
o
consistency (formed, semi formed, watery or rice water)
o visible contents (blood, mucus or worms)
Colour
o Normal
Stool: Appears brownish due to the presence of stercobilinogen. Stool from infants
appear yellow brown or yellow green.
o Colourless
Stool: Pale coloured stool is due to the absence of stercobilinogen as a result
of obstructive jaundice, abnormal fat absorption in the intestine as that occurs
during Giardiasis.
o
Brown/Black Stool: Can be a result of iron therapy, gastro intestinal bleeding
or hookworm infection.
Consistency of Stool
o Normal
Stool: Usually well formed.
o Unformed,
Semiformed/Watery Stool: Indicates bacterial or parasitic infection.
o Rice Water
Stool: Indicates cholera.
o Normal
Stool: Usually have no visible abnormal contents.
o Blood in
Stool: May be due to certain parasites (e.g. Entamoeba histolytica,
Schistosoma
mansoni) or to bacteria (Shigella sp. Enterohemorrhagic Escherichia coli) or colonic or rectal malignancies.
o Mucus:
Usually due to Entamoeba histolytica, tumour, dysentery or bacterial infection.
o Worms: Worms or segments of worms may be seen when Ascaris, Taenia or Enterobius vermicularis are the causative agents of the infection.
Microscopic Examination of Stool Specimen
Saline and
Iodine Preparation of Stool (Wet Mount/Wet Preparation/Saline Mount)
• Routinely
stool specimens are examined using the saline and iodine preparation to detect parasites,
cysts and cells.
• After the
macroscopic examination the stool specimen is prepared as follows:
o Place a
drop of saline near one end of a slide and a drop of iodine near the other end.
o Iodine is
used to stain the nuclear structure of cysts e.g. that of Entamoeba histolytica(four
nuclei) and Entamoeba coli (eight nuclei).
o Using a
wooden applicator stick, mix a small amount of specimen with the saline and a
similar amount with the iodine to make a smooth thin preparation and cover with
a cover glass.
o Examine the slide systematically, first using the 10X objective with the iris sufficiently closed to give good contrast. Use 40X objective to examine in greater detail after parasite/cyst/ova is seen.
o Report your finding
Report Findings in Stool Specimen
The following may be found in stool:
Source: Jefrey,HC,Leach R,(1991)
Something to note:
Stool
examination is requested in order to identify parasites causing several
infections.
Collection
of a good stool specimen by a patient requires a clear instruction from the clinician.
The stool should be collected within 1hour before for Examination procedure.
A stool
specimen undergoes a macroscopic examination (physical description), and a microscopic
examination to detect ova, parasites and worms.
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