Stool analysis
stool analysis
Before analysis:
- Stool sample is better provided in the lab and samples provided at home should be immediately delivered to the lab (parasites as Giardia and Entamoeba trophozoites rapidly disintegrate at room temperature ).
- stool Samples must be examined within 1 hour after being provided by the patient
Steps of analvsis:
I-Naked eye Examination to look for:
a- The presence of mucus ( especially when mucus is tinged with blood )
If mucus is present, it should be put on a slide with a droop of Iodine
(Iodene Concentration is 10% in distilled water) and examined microscopicallyfor the presence of Entamoeba trophootes, pus cells and RBCs
presence of pus cells and / or RBCs only together with mucus may be due to bacillary or amocbic dysentery or both. We should put in mind that
Entamoeba trophozoites are not regularly excreted in every stool sample of the infected person.
to differentiate between both types, either ask for another sample to look for Entamoeba trophozoites or measure the pH of stool sample
- acidic pH :is in favour of Entamoeha infection
- alkaline pH: is in favour of bacillary infection
- presence of Charcot Leyden crystals is in favor of Entamoeba infection.
Presence of mucus only in a formed stool sample may be due to : constipation or iritable colon
b-The presence of blood only may be due to piles(بواسير) or anal fissure (شرخ شرجي)
C- The prescnce of worms (Enterobius, Ascars,tTaenia segments)
d- The presence of undigested food
e - Fomed, semi-formed and soft stool samples must be concentrated by sedimentation method.
F - Loose or water stool samples are examined by direct smear method.
g-Comment on color, odour, consistency. prescnce of fat or pus
II -Microscopic examination to comment on :
1-Digestion vegetable cells, starch, muscle fibres, fat.
2- Presence of RBCs, Pus cells, Helminths eggs or larvae, Protozoa ,Yeast cells, Epithelial cells .
3- First we do screening of stool smear using the low power then the high power to confirm the details of parasites when detected.
4- When loose stool sample shows no mucus, no eggs, no larva or Protozoan parasites, we ask for the following tests :
Recomnmend: test for Cryptosporidium oocysts in stool
Recommend: test for Rota vinus antigen in stool (in patients aged between 2-5 years old).
N.B Please don't write many bacteria in stool analysis report as there is always normal bacterial flora passing down in normal stool samples.
Steps of sedimentation method:
- Use a wooden stick to collect approximately one gm of fecal sample including external and intimal portions Put in a centrifuge tube.
- Emulsify faeccal mass in the centrifiuge tube by adding 3 - 4 ml of 10% formal saline then add 3 ml of 10% formal saline, shake well .
- Sieve using a piece of gauze and plastic funnel then add 2 ml of ethyl acetate and vortex for ½ - I minute
Centrifuge at 3000 RPM for 10minutes
- Loosen the debris layer very carefally, invert the tube to discard all supernatant
- A drop of the sediment is examined under the microscope after adding 2 drops of iodine .
- After analysis
- Recommend for stool culture if many pus cells are seen with no evidence of presence of parasite.
- Recommend test for Cryptosporidium and/ or Rota virus antigen examination for watery stool samples showing no parasites .
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