Download For a stool analysis

Stool Analysis (D/R)
Stool analysis is a series of tests done on a stool (feces) sample to help diagnose certain conditions
affecting the digestive tract . These conditions can include infection (such as from parasites, viruses,
or bacteria), poor nutrient absorption, or cancer.
For a stool analysis,
1.A stool sample (more than 2 gm) is collected in a clean container and then sent to the laboratory.
2. Laboratory analysis includes microscopic examination, chemical tests, and microbiologic tests.
3.The stool will be checked for color, consistency, shape, odor, and the presence of mucus. The stool
may be examined for hidden (occult) blood, fat, meat fibers,white blood cells, and sugars called
reducing substances. The pH of the stool also may be measured.
Why It Is Done: Stool analysis is done to:
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Help identify diseases of the digestive tract, liver, and pancreas.
Help find the cause of symptoms affecting the digestive tract, including prolonged diarrhea, bloody
diarrhea, an increased amount of gas, nausea, vomiting, loss of appetite, bloating, abdominal pain and
cramping, and fever.
Screen for colon cancer by checking for hidden (occult) blood.
Look for parasites, such as Helminths,E.histolytica or Giardia lamblia.
Look for the cause of an infection, such as bacteria, a fungus, or a virus.
Check for poor absorption of nutrients by the digestive tract (malabsorption syndrome).
Requirements: Stool sample,Saline/Iodine,toothpick.slides,coverslip,pH indicator paper
Physical Examination:
a) Consistency and form: Normally faeces when passed tens to be well formed and smooth.
1.Hard: If faces appear hard they might indicate constipation.
2.Flattened and ribbon like : stool indicate some obstruction in the lumen of the bowel.
3.Semi-solid: In mild diarrhoea, digestive upsets, or after taking laxatives.
4.Watery stool: Digestive upsets, bacterial or viral infections, occasionally some poison like
arsenic.
5.Rice water stool:cholera, the stools being thin, watery, colorless and containing numerous
white mucous flakes.
6.Unformed with pus and mucus and blood: Shigellosis,Campylobacter infection.
7.Unformed or watery sometime with blood,mucous and pus: Salmonellosis.
b) Color: Normally faeces are light to dark brown.
1,Black: stools indicate bleeding into the upper gastric-intestinal tract. When stools appear
black as the result of altered blood it is termed melaena. Black stools may also result from iron
administration.
2.Clay colored stool: indicates an obstruction to the flow of bile into the intestinal canal and is
due to the increased fat,or jaundice.
3.White stool: After barium salts intake stool will appear white.
4.Bright red stool: Bleeding piles, bleeding at the lower level of the gastrointestinal tract.
5.Fresh blood with mucous: Amoebic dysentery
6.Pale,frothy,unpleasant smell stool: Giardiasis, Malabsorption.
Chemical Examination
a)pH:
Normal stools are slightly acidic, slightly alkaline or neutral. The pH values range from 6.5 to 7.5.
1. Strongly acidic stool (pH below 6.5) indicates an excess of carbohydrates in the diet.( It is
non–pathologic),and lactose intolerance. (It is pathologic).
2. Strongly alkaline stool (pH above 7.5) indicates an excess of protein in the diet. It is non–
pathologic.
3. Occult blood: Generally it is not present. If there, it indicates either infection or some disorder of
the digestive system.
b)Reducing substances: They are generally found in stools of infants suffering from diarrhea. Faecal
Reducing Substances is a test to diagnose lactose intolerance (and some rare metabolic
abnormalities). Lactose intolerance can be caused by a prolonged or severe episode of viral
gastroenteritis. Other conditions, in which other sugars, such as glucose, sucrose and fructose are
not absorbed properly, can also cause a positive test for reducing sugars in the stool.
Reducing Substances are reported as:
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Negative – this is the normal result and means that the body is digestying and absorbing sugars
properly
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Positive – this means there are substances in the stool that can act as ‘reducing agents’, i.e.
there are forms of sugar in the stool that have not been absorbed by the body.
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Abnormal Value: > 0.5 g/dL
c)Fat: The fecal fat test measures the amount of fat in the stool ,that the body does not absorb. This test
evaluates fat absorption to tell how well the liver, gallbladder, pancreas, and intestines are
working.Fat malabsorption can cause a change in your stools called steatorrhea. To absorb fat
normally, the body needs bile from the gallbladder (or liver if the gallbladder has been removed),
enzymes from the pancreas, and normal intestines. This test evaluates fat absorption to tell how well
the liver, gallbladder, pancreas, and intestines are working.
Normal value:Less than 7 grams of fat per 24 hours.
MICROSCOPIC EXAMINATION :
Requirements: Stool sample,Saline/Iodine,toothpick.slides,coverslip,pH indicator paper
Procedure:
Wet mount:Place a loopful of stool (or a small quantity with the help of toothpick) on a slide and
mix with a drop ofsaline/iodine until smooth. Cover with a cover slip. Examine under 10x and 40x
objectives. Report the presence of pus cells or muscle fibers, red blood cells,food particles,
free living amoebae, Eggs and larvae of parasites, cysts, yeast cells.
Full microscopic examination includes the following:
a)Cells:
1.Pus Cells:
Normally, a few are present. More than a few indicates bacillary dysentery or ulcerative colitis. Pus
cells or fecal white blood cells or leukocytes indicate inflammatory process in the bowel. Broadly there are two
main causes; infectious and noninfectious. Infectious causes are primarily bacteria such as E. coli,
Shigella,salmonella, campylobacter. Noninfectious most common causs is ulcerative colitis.
2.Epithelial Cells
Normally a few are present. If many are present, however, it indicates inflammation of the bowels.
3.Macrophages: Large mononuclear phagocytes with nucleus and ingested WBCs.
Normally, present only occasionally.If many are present, it indicates bacillary dysentery or ulcerative
colitis.
4.Eosinophil: may be present in allergies.
5.Erythrocytes (Red Blood Cells)
Normally absent. If present, it indicates lesions in the colon, rectum or the anus. If clumped, it means
amoebiasis (a kind of infective dysentery).
Note:Cells are usually reported as the number seen per high power field.
b) Crystals: Phosphates, oxalate, Calcium carbonate, Calcium sulphate, Charcot Leyden crystals.
~Triple phosphate crystals are normal constituents of faeces and occur as “coffin lid” shaped
crystals
~.Calcium oxalate crystals, occur most frequently when fruits and vegetables rich in
oxalates are eaten.
~Crystals of calcium carbonate and calcium sulphate occur only occasionally.
~Charcot Leyden crystals are seen as almost needle shaped octahedral. They are sometimes
found in large number in the faeces of patients with worms or amoebiasis.
c)Food residues:Undigested and unabsorbed foods. These include fats, muscle fiber, starch
granules, indigestible constituents, such as vegetable cells residue, Cellulose fibers and connective
tissue.
d) Fats:Neutral fats are seen as oily globules, usually colorless. Fatty acids appear as colorless
needle-shaped crystals usually in groups, but they may occasionally form flakes.
Other Findings
1. Yeast cells: Normally present.
2. Bacteria: Normally gram negative are present.If a high percentage of gram positive bacteria are
present, it indicates intestinal ulceration.
e) Intestinal Protozoa/Parasite: Iodine colors the egg and larvae and help in easy visulazation
of trophozoites also.
Note:Parasitic amoebae, eggs, larvae and cysts are usually reported as the number seen in the entire
preparation as follows.
Scanty (rare) 1-3, 3-10 (+), 10 to 20 (++), 20 to 40 (+++), and more than 40 (++++).
There are pathogenic and non–pathogenic protozoa found in stool.
Non–pathogenic:
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Entamoeba coli–cysts or vegetative form.
Entamoeba coli cyst
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Iodamoeba butschili – cysts.
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Endolimax nana – cysts.
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Pathogenic:
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Entamoeba histolytica – cysts or vegetative form.
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Entamoeba histolytica – cysts or vegetative form.
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Giardia lamblia–cysts.
Giardia lamblia–cysts and trophozoites.
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Balantidium coli:
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:Left fig:Cyst
Right.fig:Trophozoite.
Nematohelminths
They are pathogenic in nature.e.g
Ascaris lumbricoides (roundworm).
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Stool C/S (Culture snd Sensitivity)
A stool culture is done to:
1,Find the cause of symptoms, such as severe or bloody diarrhea, an increased amount of gas, nausea,
vomiting, loss of appetite, bloating, abdominal pain and cramping, and fever.
2.Find out and to identify bacteria associated with enteric diseases e.g Salmonella, Shigella,
Campylobacter, Aeromonas, and predominating numbers of Staphylococcus organisms, yeast, and
Vibrio.that are causing infections or diseases, such as food poisoning, inflammation of the large intestine
(colitis), cholera, and typhoid. Of all specimens collected, feces are likely to contain the greatest
number and greatest variety or organisms
3.Identify a person who may not have any symptoms of disease but who carries bacteria that can spread
infection to others. This person is called a carrier. A person who is a carrier and who handles food is likely
to infect others.
4.Find out if treatment for an infection has been effective.
Requirements: Stool sample,wireloop.slides,Gram stains kit,antibiotic discs.
Media: EMB,SS agar, Mackonkey agar.TCBS (Thiosulfate-Citrate-Biosalts-Sucrose agar),
TSI,SIMS,Mueller Hinton agar.
Procedure:
1.Sterile the wireloop to red hot.Stab loop in areas where there is mucus,pus or blood.
2.Streak on EMB and SS agar.
3.If Cholera is suspected,.inoculate a TCBS plate.
4.Incubate the plates for 24 hr at 37C.
5.Next day observre the colonies.If there are colorless colonies,inoculate them on TSI for further
investigation.
6.Next day observe TSI also.
7.Set up sensitivity in Mueller hinton plates by making lawn from EMB and SS agar plates.
8.Incubate at 37C for 24 hr.
9.Next day not zones of inhibitions.