FECAL MICROSCOPIC EXAMINATION

Effective Date: 
Thu, 08/01/2013
Reviewed: 
Tue, 01/10/2017
Revised: 
Fri, 08/09/2013
Policy: 

 Purpose and Scope:

 The microscopic examination may be used to determine the presence of leukocytes and erythrocytes in a fecal smear. This will very quickly give the clinician information on the patients disease state. Determination of the presence of leukocytes may be useful in the initial workup of patients with diarrhea possibly due to bacterial infection.

Reagents and Supplies:

 Gram Stain Kit  (Hardy Diagnostics)

            Crystal Violet Reagent

            Stabilized Iodine Reagent

            50% Acetone/Alcohol Decolorizer

            0.4% Safranin

Microscope Slides

Microscope with oil immersion lens

Blotting paper

Heating block

 Reagent Storage:

  • Store Gram Stain Kit at Room Temp.
  • Do not use after expiration date on kit

 Quality Control:

 See Quality Control for Gram Stain Procedure (SOP Micro-02)

 Procedure

Gram Stain Procedure:

  1. Apply stool specimen to clean microscope slide using an applicator stick to yield a thin, uniform smear.
  2. Allow to air dry.
  3. Cover slide with Crystal Violet Reagent for 1 minute. Gently rinse with tap water and Allow to drain.
  4. Cover slide with Iodine Reagent for 1 minute. Gently rinse with tap water and allow to drain.
  5. Rinse slide with Decolorizer until it runs off the slide with no color. Do not over-decolorize. Gently rinse with tap water and allow to drain,
  6. Cover slide with Safranin Counterstain for 30-60 seconds. Gently rinse with tap water and allow to drain. Place slide between sheets of blotting paper to dry.
  7. Place a small drop of oil on the stained specimen and examine slide under oil immersion lens.

Wet Mount Procedure:

  1. Apply stool specimen to clean microscopic slide using an applicator stick, add 1 or 2 drops of normal saline and thoroughly emulsify.
  2. Mount with a coverslip. A satisfactory preparation should have a slightly opaque density but be sufficiently thin to allow newspaper print to be legible through it.
  3. Examine slide by methodically scanning each field of the entire coverslip with the 10X objective, going to high dry (40X) to examine suspicious objects more carefully.

 

Interpretation:

Report presence (or absence) of leukocytes and erythrocytes as:

  • No leukocytes  (or white  blood cells) or erythrocytes (or red  blood cells) seen
  • Rare:   1-5  seen  total
  • Occ (1+): >5 seen,  <1/HPF
  • Few (2+):  1/4 field
  • Mod (3+):  1/2 field
  • Many (4+):  >1/2 field

 When examining stool smear, look for the “lobe” of the white blood cell as stools contain food particles and debris that may  resemble white  blood cells.

Also report presence of abnormal flora including yeast.

When examining stool smear, look for the “lobe” of the white blood cell as stools contain food particles and debris that may resemble white blood cells.

Also report presence of abnormal flora including yeast.

 

REFERENCES

Bailey and Scott,  Diagnostic Microbiology,  4th  Edition,  1974,  C.V.  Mosby,  St. Louis, pp.  392  - 393.

Product insert,  Hardy  Diagnostics,  Santa  Maria,  CA.

Medical  Laboratory Observer,  September 1995,  “Tips from the  Clinical  Experts;  Fecal Leukocytes”

Todd,  Sanford,  and  Davidsohn,  Clinical  Diagnosis and  Management by Laboratory Methods, 17th  Edition,  1984, W.  B.  Saunders Company,  Philadelphia,  pp.  1212  - 1213.