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Stool RE & ME Susmita Chakrabarty

Stool Examination

If you’ve been having stomach problems, your doctor might order a stool examination or ask for a stool sample. This test can look in your poop for parasitic infection, abnormal cells or other germs that might be making you sick.

Stool samples should be evaluated macroscopically in terms of color, consistency, quantity, form, odor, and presence of mucus. The presence of a small amount of mucus in stool is normal. However, the presence of copious mucus or bloody mucus is abnormal.

Why Do You Need It?

Your doctor could order this test if you show any of these symptoms:

  • Diarrhea that lasts more than a few days
  • Poop that contains blood or mucus
  • Stomach pain or cramping
  • Nausea
  • Throwing up
  • Fever

Your doctor may be more concerned if:

  • You’re very young or elderly
  • You have a weakened immune system
  • You’ve traveled outside the United States
  • You’ve eaten contaminated food or water
  • Your symptoms are severe

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:

  1. Gram Stain Kit (Hardy Diagnostics)
  2. Crystal Violet Reagent
  3. Stabilized Iodine Reagent
  4. 50% Acetone/Alcohol Decolorizer
  5. 0.4% Safranin
  6. Wright's One Step Stain
  7. Distilled Water
  8. Microscope Slides
  9. Microscope with oil immersion lens
  10. Blotting paper
  11. Heating block

Reagent Storage:

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

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.

Wrights 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. Using a disposable pipet, cover the slide with Wright's stain and let stand for approximately 20 seconds.
  4. Rinse with distilled water.
  5. Tilt and air dry until dry.
  6. Examine the slide under oil, using an 100X oil lens.

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.

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