Stool Analysis Interpretation Through this presentation, I try to help family physicians to better understand and utilize the stool analysis. references include http://www.labpedia.net

1. Stool Analysis Interpretation
DAWOOD AL NASSER
Saudi Board of Family Medicine Trainee
2018- 1 April

4. ”
“
Indicationsof Stool analysis

5. Indications
1. To rule out the presence of WBCs and RBCs.
2. To find ova or parasites.
3. To see the presence of fat for malabsorption
syndrome.
4. For screening of colon cancer.
5. For asymptomatic ulceration of GI tract.
6. Evaluate diseases in the presence of diarrhea and
constipation.

7. The stool is examined :
Grossly.
microscopically.
Chemically.

8. Normal Findings
Quantity 100 to 200 grams.
Amount of water 75 %
Color in adults yellowish brown
Color in infant green and stool is loose or pasty.
pH 7.0 to 7.5 may be acidic with high
lactose intake

9. RBCs. absent
Epithelial
cells
present and these are increased with GI tract irritation
WBCs Few WBCs are seen and these may be increased with G I tract
inflammation
Crystals Crystals of calcium oxalate, fatty acids, and triple phosphate are
commonly present.
Undigested
vegetable
fibers
sometimes
Neutral fat
globules
May be seen
Hematoidin
crystals
after GI tract
hemorrhage.

10. Urobilinogen 40 to 280 mg / 24 hours
Fat Normally absent and this is less than 7 grams / 24 hours
less than 30 % of dry weight (This is on diet of 50 grams of fat per day).
Calcium about 0.6 gram / 24 hour’s.
Occult blood normally is negative.

12. Stool Analysis results
Color yellowish
brown
Occult blood +ve
Ph 7.1
Parasites Not seen
RBCs NA
Pus cells Not seen
Food cells Not seen
Mucus Not seen
•50 years old male presented for
interpretation of his annual screening
laboratory results
1-what are the possible causes of this
result ?
2-what instructions should be given
before FOBT ?
Case 1

13.  Instruct the patient to stop vit.C, iron-containing drugs,
meat and vegetable for at least three days prior to the test.
 False positive OB test is seen in:

14. False +ve causes

15.  Ingested meat.
 Peroxidase rich vegetables like turnip, horseradish,
mushroom, broccoli, beans, sprouts, cauliflower, oranges,
bananas, cantaloupe, and grapes.
 Drugs may lead to bleeding like anticoagulants, aspirin, iron
preparation, nonsteroidal antiarthritic drugs, and steroids.
 Vit C may cause a false negative.
False +ve causes

16. Possible cause of true +ve FOBT
Gastrointestinal tumors.
Inflammatory bowel disease.
Diverticulosis.
Varices.
Ischemic bowel disease.
Arteriovenous malformations
of GI tract.
Haemorrhoids.
Blood swallowed from oral
cavity or nasopharynx.
Adenoma.
Gastric carcinoma.
Peptic ulcer.
Gastritis.
Amyloidosis.
Kaposi’s sarcoma.

17. Alternative test :
FIT:
Fecal Immunochemical
Test
advantages
more specific for
hemoglobin, it avoids
some of the false-positive
results of FOBT and
does not require the same
dietary restrictions.
More sensitive to detect
lower (GI) bleeding
disadvantages
no randomized controlled
trials evaluating the
benefits of FIT
FOBT had a higher
sensitivity for advanced
adenomas than FIT

18. Stool Analysis results
Color yellowish brown
Occult blood -ve
Ph Acidic <7.0
Parasites Not seen
RBCs NA
Pus cells Not seen
Food cells Not seen
Mucus Not seen
odor bad odor
reducing
substances
> 500 mg/dL are
reducing substances in
the stool.
•25 y/o Female c/o intermittent
abdominal bloating with unknown
aggravating or relieving factors
1-what are the possible causes of this
result (in correlation with hx.)?
2- what is the confirmatory test for the
suspected diagnosis
Case 2

19. Reducing substances
 Precaution
 stool should be delivered to the laboratory as soon as possible, preferably
within 1 hour.
 This is because lactose (or other sugars) in the stool will normally be
broken down by chemical processes within 2 to 4 hours.
 Avoid contamination with urine or other material like water or toilet paper.
 Indication
 To diagnose the intolerance to disaccharides.

20. Reducing
substances are :
glucose.
Fructose.
Lactose.
galactose.
Pentose.
Carbohydrate
malabsorption is a
major cause of :
Watery diarrhea.
Electrolyte imbalance.
There may be idiopathic
lactase deficiency.
This is seen in 70 to 75 % of
southern European, Greek,
and Indian.
Blacks have 70 %.
Asian adults have > 90 %.
caucasian American adults
have 5 to 20 %.
Reducing substances

22. Increased reducing
substances are seen
in:
carbohydrate
malabsorption is
seen in :
1-Disaccharidase enzyme deficiency
in the intestine.
2-Short bowel syndrome.
3-Idiopathic lactase deficiency leads
to lactose intolerance.
1-celiac disease (Sprue).
2-viral gastroenteritis.

23. Confirmation of hypolactasia
The measurement of breath hydrogen after ingestion of 25 to 50 g of lactose is more sensitive and
specific than the lactose tolerance test.
The breath hydrogen test has become widely available and is often used rather than the lactose
tolerance test.
The breath hydrogen test is based on the principle that carbohydrate in the colon is detectable in
pulmonary excretion of hydrogen and other gases.
A rise in breath hydrogen concentration greater than 20 ppm over baseline after lactose ingestion
suggests hypolactasia.
The lactose breath hydrogen test is positive in 90 % of patients with lactose malabsorption.

24. Stool Analysis results
Color reddish
Occult blood +ve
Ph NA
RBCs many
Pus cells Not seen
Food cells Not seen
Mucus Not seen
WBC Few with Charcot-Leyden
crystals, indicating the
presence of eosinophils.
•10 y/o male who frequently eats
unpeeled fruits and vegetables c/o
malaise, weight loss, severe abdominal
pain, profuse bloody diarrhea,
previously misdiagnosis of appendicitis
was given
1-what are the possible causes of this
result (in correlation with hx.)?
2- what is the confirmatory test for the
suspected diagnosis
Case 3

25. Entamoeba histolytica
Charcot-Leyden crystals are seen in
parasitic infestation especially in
amoebiasis.
Traditional O&P (ova and parasite) stool testing for amebiasis should use at least three fresh samples to
increase sensitivity. However, this test has recently fallen out of favor because an E. histolytica stool
antigen test with a sensitivity of 87 % and a specificity of >90 % has become available.
Positive stool samples are likely to be heme positive and
to have low neutrophils
Serologic tests such as ELISA and agar gel diffusion are >90% sensitive, but these tests often become negative
within a year of initial infection.

26. Stool Analysis results
Color Gray
Occult blood -ve
Ph acidic (<7.0)
RBCs Not seen
Pus cells Not seen
Food cells Fat globules 3+
Mucous Not seen
WBC Not seen
Odor
Foul smelling
•25 y/o female who is trying hard to
lose weight(BMI>34) complains of hard
to flush greasy stools for 1 month
1-what are the possible causes of this
result (in correlation with hx.)?
2- what is the confirmatory test for the
suspected diagnosis
Case 4

27. steatorrhea
Fat presence shows
the possibility of
Malabsorption.
Deficiency of
pancreatic digestive
enzyme.
Deficiency of Bile
Fat globules
Neutral fat globules,
stained with Sudan
may be seen normally
0 to 2 +.
Fat
Normally absent and this
is less than 7 grams / 24
hours during three days
period.
This is less than 30 % of
dry weight (This is on diet
of 50 grams of fat per
day).

28. orlistat [Xenical; inhibits fat absorption

30. Stool
Analysis
results
Color reddish
Occult blood +ve
Ph NA
RBCs many
Pus cells many
Food cells NA
Mucous Present
WBC Calprotectin +ve (elevated
level)
Lactoferrin +ve
Odor NA
•40 y/o c/o bouts of rectal bleeding,
diarrhea, pain, and tenesmus. There is
hx. of loss of appetite ,nausea and
vomiting and weight loss, fever, and
anemia were also reported
1-what are the possible causes of this
result (in correlation with hx.)?
2- what is the confirmatory test for the
suspected diagnosis
Case 5

31. The diagnosis of IBD is usually supported by colonoscopy (and biopsy). Laboratory testing should include a
complete blood count, fecal leukocyte level, erythrocyte sedimentation rate (helps severity identification
), and fecal calprotectin level.
Remember that mucus can be present in IBD (Crohns and Ulcerative colitis) and IBS…
If IBD is diagnosed or suspected lactoferrin test may be ordered to monitor disease activity and
to help evaluate its severity.

32. Lactoferrin is related calprotectin. Both are substances that are released by WBC in the stool and are
associated with intestinal inflammation.
Of the two tests, calprotectin has been the most extensively studied and it is ordered more frequently
than lactoferrin.
Usually one or the other will be ordered but not both.
A baby that is being breast-fed could potentially have a false-positive result because of lactoferrin
present in the mother's breast milk.

33. Stool Analysis results
Color brownish
Occult blood -ve
Ph NA
RBCs non
Pus cells non
Food cells non
Mucous non
WBC NA
Odor NA
87 y/o woman was readmitted to the hospital
because of recurrent pneumonia. She is still
taking her moxifloxacin (Avelox) and
doxycycline (Vibramycin). At night the patient
was febrile ,and CBC showed leukocytosis (36 ×
109 per L),besides she had several loose bowel
motions.
1-what are the possible causes of this result (in
correlation with hx.)?
2- what is the confirmatory test for the
suspected diagnosis
3-How would you treat her ?
Case 6

34. Confirmatory test/and Gold Standard test
The most common confirmatory study is an enzyme immunoassay for C. difficile toxins A and B.
The test is easy to perform, and results are available in two to four hours. Specificity of the assay is
high (93 to 100 percent), but sensitivity ranges from 63 to 99 percent.
If necessary, rapid diagnosis of C. difficile–associated diarrhea can be made by flexible sigmoidoscopy
or abdominal computed tomography (AAFP Rec. C).

35. The gold standard for the diagnosis of C. difficile–mediated disease is a cytotoxin assay. Although
this test is highly sensitive and specific, it is difficult to perform, and results are not available for 24 to
48 hours.

36. Sigmoidoscopy revealed diffuse
pseudomembranes throughout the
patient’s distal colon, confirming C.
difficile infection

37. Tx of C.difficile
Metronidazole (Flagyl) 500 mg orally every six to
eight hours for 10 to 14
days
Alternatives: 250 mg every
six hours for 10 to 14 days
and 500 mg IV every eight
hours for 10 to 14 days
Oral and IV
Vancomycin (Vancocin) 125 to 500 mg orally every
six hours for 10 to 14 days
Oral only†
Nasogastric tube
Retention enema

38. ”
“Few important hints …

39. Colors…

40. 1.Normal color is due to the presence of stercobilinogen.
2.Yellow or yellow-green color is seen in diarrhea.
3.Black and tarry ( related with consistency) stools are due to
bleeding of upper GI tract from tumors.
4.Maroon or pink color is from lower GI tract due to tumors,
hemorrhoids, fissure, or inflammatory process.
Color…

41. 5.Clay-colored stools are due to biliary obstruction.
6.Mucous in the stool indicate constipation, colitis or malignancy.
7.Pale color with greasy appearance is due to pancreatic deficiency
leading to malabsorption.
Color…

42. The color of the stool Causes
1. Brown, dark brown or
yellow-brown
Normal color is due to oxidation of bile pigments.
2. Gray color Ingestion of chocolate or Cocoa. steatorrhea
3. Black Iron or bismuth ingestion, bleeding from the upper
GI tract.
4. Very dark brown Diet high in meat.
5. Red color Diet high in beats, laxatives of vegetable origin,
Bleeding from lower G I tract.
6. Green or yellow-green Diet high in spinach, green vegetables.

43. pH of the stool depends upon the diet and bacterial
fermentation in the small intestine
Carbohydrate changes the pH to acidic
while the protein breakdown changes to alkaline.
pH stool test helps to evaluate carbohydrate and fat
malabsorption.
pH stool also helps to know disaccharidase deficiency.
pH

44. Stool pH
Normally
Alkaline ( Increased
pH )
Acidic ( Decreased
pH )
Normally stool is slightly
acidic or alkaline.
pH is 7.0 to 7.5
depending upon the diet.
Colitis.
Villous adenoma.
Diarrhoea.
Antibiotic therapy.
Fat malabsorption.
Disaccharidase deficiency.
Carbohydrate
malabsorption.

45. Stool findings Causes
1. Diarrhoea mixed with blood and
mucous
Typhoid, Amoebiasis and large colon carcinoma
2. Diarrhoea mixed with Pus and mucous Ulcerative colitis, Salmonellosis, Intestinal
tuberculosis, Shigellosis, Regional enteritis and
acute diverticulitis
3. Patty stool with high-fat contents Cystic fibrosis and CBD - obstruction
4. Formed stool with attached mucous Constipation, Mucous colitis, and excessive
straining
5. Small, hard dark balls like Constipation
6. Clay-colored, pasty and little odor Bile duct obstruction, and barium ingestion.
7. Black, tarry, sticky, watery, voluminous Upper GI tract bleeding, Noninvasive infections
like Cholera, Staphylococcal food poisoning and
Toxigenic E. Coli and Disaccharidase deficiency.

46. muscle fibers..
 muscle fibers are seen in the stool. Their presence show defect in the digestion.
The increased amount of muscle fibers are found in :
 Malabsorption syndrome.
 A pancreatic functional defect like cystic fibrosis.

47. ”
“Home message:
Do not rule out a diagnosis using a single test
Do not forget false positive and false negative tests
Use clinical hx. and examination to guide the
interpretation of lab results.

48. Have a good day
References :
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