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Chapter 17Fecal Analysis

Professor A. S. Alhomida

Chapter 17Fecal Analysis

Professor A. S. Alhomida

DisclaimerDisclaimer The texts, tables and images contained in this course presentation (BCH

376) are not my own, they can be found on: References supplied Atlases or The web

King Saud University

College of Science

Department of Biochemistry

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Fluid Regulation in GI TractFluid Regulation in GI Tract

1. Approximately 900 mL of ingested fluid, saliva, gastric, liver, pancreatic, and intestinal secretions inter the digestive tract each day

2. 500-1500 mL of this fluids reaches the large intestine, and only about 150 mL is excreted in the feces (stool)

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Fluid Regulation in GI Tract, Fluid Regulation in GI Tract, Cont’dCont’d

3. Water and electrolytes are absorbed in both small and large intestines

4. Large intestine can absorb about 300 mL of water, when the amount of water exceeds this amount is excreted in the feces producing diarrhea

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Fluid Regulation in GI TractFluid Regulation in GI Tract

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Specimen CollectionSpecimen Collection

1. Routine Specimens

• Qualitative Testing

2. Timed Specimen

• Quantitative Tests

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Component % of Total Weight

Water 75

Solid 25

% of Total Solids

Cellulose & Other Indigestive Fiber Variable

Bacteria 30

Inorganic Material (mostly Ca & Ph( 15

Fat & Fat Derivatives 5

Composition of Feces on an Composition of Feces on an Average DietAverage Diet

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1. Macroscopic Screening• Color• Appearance

2. Microscopic Examination• Fecal Leukocytes• Muscle Fibers• Qualitative Fecal Fats

(Steatorrhea)

Fecal Analysis TestsFecal Analysis Tests

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Fecal Analysis Tests, Cont’dFecal Analysis Tests, Cont’d

3. Chemical Tests

1. GI Tract Bleeding (Occult Blood )

2. Quantitative Fecal Fat Tests

3. Fetal Hemoglobin (Apt Test)

4. Fecal Enzymes

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Fecal Analysis TestsFecal Analysis TestsCChemical Tests, Cont’dt’d

5. Carbohydrates

6. Liver diseases

7. Biliary duct disorders

8. Maldigestion and Malabsortion Syndromes

9. Inflammation

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Fecal Analysis TestsFecal Analysis Tests

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Macroscopic Screening TestsMacroscopic Screening Tests

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Fecal Screening TestsFecal Screening Tests

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Fecal PigmentsFecal Pigments

1. Normal color of feces is influenced by both amount of uroblin present and the kind of food taken

2. Largely vegetable diet gives light-colored stools while one rich in meats gives darker, brown color

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Fecal Pigments, Cont’dFecal Pigments, Cont’d

3. Undigested portions of some vegetables may color the stools

• Carrots Reddish-brown

• Spinach Greenish

• Fruits Bilberries, grayish-purple

• Milk diet Pale-yellow or Orange

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Abnormality of Fecal Abnormality of Fecal CompositionsCompositions

• Steatorrhea

1. Abnormality of absorption and digestion of lipids

2. It occurs when obstruction of flora of bile due to the biliary obstruction

3. Leads to increase fat content of stools

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Abnormality of Fecal Abnormality of Fecal Compositions, Cont’dCompositions, Cont’d

• Occult Blood

1. When bleeding is severe, the stools are dark color

2. Bleeding > 2.5 mL/150 g of stool is considered pathologically significant

3. In intestine, oxyhemoglobin is converted to hematin and porphyrins

4. Only hematin gives +ve results with fecal occult blood test

5. Ulcers and cancers of color give +ve results

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Occult Blood Tests

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THE ENDTHE END

Any questions?