Routine examination of stool

STOOL EXAMINATION

Presented by: Dr. Priyanka Buragohain

Guided by:Dr. Hemen Kalita

Deptt. Of Roga Nidan. Govt. Ayurvedic College

Stool examination by Dr. Priyanka Buragohain

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DEFINITION

• Human feces is called as stool.• faeces / feces is plural of latin term faex

meaning RESIDUE.• It is the waste residue of indigestible materials

of an animal’s digestive tract expelled through the anus during defecation.

• Meconium is newborn’s first feces.• SCATOLGY or CAPROLOGY is the study of feces.


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COMPOSITION

• ¾ water, ¼ solid• Undigested and unabsorbed food• Intestinal secretions, mucous• Bile pigments and salts• Decomposed products• Bacteria and inorganic material• Epithelial cells, leukocytes.


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PRECAUTION BEFORE COLLECTION

• Patient should avoid the following things for at least 48 hours before collection of stool:

• Mineral oils, bismuth, non absorbable anti diarrhoeal drugs, antimalarial drugs, antibiotics, etc

• Pt. Should not have barium swallow examination before stool R/E

• Avoid iron containing drugs, meat, fish etc for atleast 48 hours before stool for occult blood.

• In constipated patients use only non residual purgative


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COLLECTION• Universal precautions• Pt. is asked to pass stool in a clean container.• Stool should be collected in a steralized, wide mouthed container.• Loose/last/portion containing mucus, blood etc is to be collected

in a wide mouthed bottle.• Should be uncontaminated with urine or any other body

secretions.• >2gm is required.• Properly named and always a fresh sample should be tested.• Liquid stool to be examined within ½ hour• Solid stool to be examined within 1 hour.• If delayed store in a refrigerator.


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COLLECTION CONTD...

• 3 samples of stool within 10 days to exclude false negatives.

• 2 samples to be examined on alternate days after normal defaecation and 1 sample after a purgative for certain worms.

• Formalin is the best preservative. It kills the bacteria but ptreserves the protozoa and helminthes.

• For culture no preservatives to be used


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TYPES OF EXAMINATION• PHYSICAL EXAMINATION: colour, volume, consistency,

odour, mucus, pus, concreations, helminths.

• CHEMICAL EXAMINATION: reactions, occult blood, fat, carbohydrate, protein, etc

• MICROSCOPIC EXAMINATION: remnants of food, pus cells, macrophages, RBCs, crystals, bacteria, yeasts, molds, protozoa, helminths.

• STOOL CULTURE:


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Physical examination• AMOUNT• CONSISTENCY• COLOUR• ODOUR• REACTION• MUCUS

• CONCRETION• BLOOD• PUS• FOOD REMNANT• UNDIGESTED TABLETS


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MACROSCOPIC EXAMINATION

AMOUNT• Normal is 150 g to 200 g/day• Increased in steatorrhoea, diarrhoea, indigestion

of carbohydrate.


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CONSISTENCY OR FORM

• Normal is soft but formed• Excessively hard/scybala- habitual constipation• Flattened or ribbon like-intake of excess of mineral

oil, carcinoma of rectum, stricture of rectum• Soft, mushy, liquid and voluminous- diarrhoea,

intake of purgatives• Small numerous, largely mucus and blood with

small amount of stool- dysenteries• Rice watery without fecal matter- Cholera

12Stool examination by Dr. Priyanka Buragohain

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Colour

• Dark Grey- excessive cocoa or chocolate ingestion

• Reddish or blackish brown- large amount of fruits• Green – ingestion of green leafy vegetables,

administration of calomel due to biliverdin• Red – Beat ingestion fresh blood• Yellow – rhubarb or senna ingestion, normal

stool



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• Clay – obstructive jaundice, barium meal x-ray • Tarry black – haemorrhage in stomach/upper

intestine• Dark brown to bright red – bleeding in rectum

or sigmoid colon• Red streaks of blood on the surface of faeces-

haemorrhoids, fissures, carcinoma ,ulcerative colitis


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Odour

• Normal odour is aromatic due to indole and skatole

• Increased- excessive protein ingestion• Sour rancid- fatty acid in milk indigestion (in

children and adults), normal in infants• Putrid- severe diarrhoea of malignancy,

gangrenous dysentry


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Reaction

• Normal is neutral• Ph varies from 6.9 to 7.2• pH is dependent on bacterial fermentation

and putrefaction in the bowel. • Alkaline – excess protein ingestion• Acidic – excess carbohydrate ingestion


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Mucus

• Small quantity of mucin is normal• Small quantity – faeces from small gut • Excessive quantity – infection of intestine• Entirely mucus with little or no faeces and

streaks of blood- dysentery, ileo colitis, intussusception


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Concretion

• In infants whitish curds may be found • Gall bladder stones may be rarely found


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Blood

• Absent in normal faeces • Formed stool with streaks of blood – lesion in

sigmoid colon, rectum or anal canal• Liquid stool with bright red blood, pus and

mucus- bacillary dysentery, ulcerative colitis • Semi formed stool with deep tarry black blood-

melena • Loose stool with deep cherry red blood- melena


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Pus

• Normally absent• Pus with blooded mucus- ulcerative colitis,

bacillary dysentery, ulcerative carcinoma


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• GROSS FOOD REMNANTS MAY IN NORMAL STOOL

• UNDIGESTED TABLETS MAY BE FOUND


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CHEMICAL EXAMINATION


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Chemical Examination Of Stool

• Acidity/basicity• Fats• Nitrogen• Stercobilinogen• Coproporphyrin• Occult blood• Reducing substances• N. B : most commonly used chemical examination

of stool is pH, occult blood and reducing substances


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FATS• Normally upto 20% of total solids• Lipids are measured as fatty acids:2-5 gm/24 hrs• Known dietary intake and timed stool collection.• Take diet containing 100 gm of fat daily, 3 day stool collection.• >6 gm/day is abnormal

• Quantitative or semiquantitative methods: Gravimetric method Isotopic techniques(radio-isotopes) Electrical capacitance method Titrimetric method of Van de Kamer


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Titrimetric method • Boil with alcoholic potassium hydroxide to

convert fats and fatty acid into soap• cool• HCl is added to convert soap to fatty acid• Fatty acid extracted with petroleum ether• Aliquot is evaporated, taken up in neutral alcohol• Ttitrate with sodium hydroxide • Fatts are calculated as fatty acids


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Electrical capacitance methods• Fecal suspension is extracted with solvent

specially with chlorinated benzene• Extract is filtered • Electrical capacitance is measured and

compared with standard of triolein simillarly treated


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Interpretation• Fecal fat increase in• enteritis and pancreatic disease (lack of lipase)• Surgical removal of a section of intestine • Mal absorption syndrome • Chronic pancreatic disease(> 10 gm / 24 hr)• Neutral fat increase in • Use of rectal suppositories • Ingestion of castor oil or mineral oil• Ingestion of dietetic low calories mayonnaise• Tropical sprue


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Nitrogen

• Varies with the amount and nature of diet• Normal is 1 to 1.5 gm /day• Increase in azotorrhoea, pancreatic achylia,

pancreatogenous fatty diarrhoea, idiopathic steatorrhoea


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Stercobilinogen

• Normal is 40 to 280 mg/day• Average is 150 mg/day• Dependent on amount of bilirubin passing to

intestine(jaundice)


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Coproporphyrin

• Normal is 300 to 1100 mg/ day• Type 1 – 70%• Type 3 – 10 to 30%• Abnormally increased in congenetial

porphyria• Abnormallly decreased i9n liver disease like

cirrochis, hepattitis, passive4 venous congestion, metastatic carcinoma in liver


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Occult blood

• Detect blood which is present in amount or form not visible macroscopically

• Normally nil• Abnormal presence in condition of occult

haemorrhage in the GI tract • BENZIDINE TEST• GUAIAC TEST• ORTHOTOLIDINE TEST• Most commonly used test is benzidine test


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BENZIDINE TEST

• 4 gm benzidine in 100 ml of glacial acetic acid• Emulsify pea sized bit of faeces in 5 ml of

water.• Mix 1 ml emulsion and 1 ml of reagent in test

tube• Add several drops of 35 H2O2• Blue colour indicates positive reaction


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• Trace- faint blue colour after 1 min

• 1+ - definite blue green slowly• 2+ - green blue rapidly• 3+ - blue almost immediately• 4+ - dark blue immediately


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GUAIAC TEST• Less sensitive• With loss of 20 to 30 ml of blood

all test will be positive• Guaiac reagent consist of 1 gm

Guaiac in 5 ml of 95% ethanol.• Make a small smear of feces on a

filter paper• Add 2 to 3 drops of gum guaiac

solution + 2 to 3 drops of glacial acetic acid + 2

to 3 drops of 3% H2O2


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• Trace- faint blue green in 1 min• 1+ light blue slowly• 2+ clear blue rapidly• 3 + deep blue almost immediately• 4+ deep blue immediately


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ORTHOTOLIDINE TEST• Intermediate sinsitivity• Smear the stool on a filter paper with an

applicator• Pipette a few drops of the reagent on to the

filter paper(orthotolidine barium peroxide 200 mg+ glacial acetic acid 5 ml)

• After 30 sec examine for a blue colour• Blue green colour within 30 sec means

positive test


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Interpretation

• Gastric disease eg chronic ulcer and malignancy

• Intestinal diseases eg dysentery, typhoid fever, carcinoma

• Haemorrhoids• During instrumentation


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Faecal reducing substance test

• To diagnose lactose intolerance• Sample of 5 gm stool is needed• Sample needs to be delivered to the

laboratory as soon as possible, preferably within 1 hr , cause lactose in the stool will normally be broken down by chemical processes within 2-4 hrs after the specimen is produced.


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Interpretation

• Negative/ trace- < 0.25 g/dl• Suspicious(grade 1) – 0.25-0.5 g/dl• Abnormal(grade 2-4)->0.5 g/dl• Found in Carbohydrate malabsorption• Tropical sprue


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MICROSCOPIC EXAMINATION


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NEED FOR MICROSCOPIC EXAMINATION

• For the diagnosis of microscopic elements.• Trophozoites and its movements are better seen

in unstained preparation of a fresh material.• Cystic forms &Nuclear character are better seen

in stained preparation(iodine)• Gycogen mass- stained with iodine• Chromatoid bars- unstained preparation• N.B – Both stained and unstained materials are

to be prepared


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Need of concentration technique

• To see whether treatment of parasite is successful

• To find ova of S. Mansoni or Taenia if few or other ova and cyst are not seen in routine examination

• To examine stool specimens from patients who do not come from an area where a particular parasite is found


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FLOATATION TECHNIQUE• Use solutions which have highier specific

gravity(zinc sulphate or Sheather’s sugar) than the organisms to be floated so that the organisms rise to the top and the debries sink to the bottom.

• Advantage – produce a cleaner material than the sedimentation technique

• Disadvantage – walls of eggs and cyst will often collapse, hindering identification.

• Some parasite eggs do not float.


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SEDIMETATION TECHNIQUE

• Use solutions of lower specific gravity than the parasitic organisms(formalin ethyl acetate technique)

• Recommended for general diagnostic laboratories due to easy to perform and less prone to technical error.


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Sedimentation techniques• Mix a small piece of stool with 10 ml of water or saline in a tube/ bottle• Sieve the suspension into a beaker through a strainer with small holes.• Pour the contents into a centrifuge tube• Centrifuge at 2000-3000/rpm for 1 min• Pour off the supernatant part• Resuspend the deposit in clean water and add enough water to fill the tube.• Mix well and recentrifuge• Pour off the supernatant part• Resuspend in zinc sulphate solution, fill the tube with the solution• Centrifuge at high speed for 1 min• Transfer the contents from the surface of the tube to a slide, using a bacteriological

wire loop• Add small drops of saline and mix• Cover with a cover slip• Examine under 10x and 40x objectives


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Stainning methods

Wet mountnormal saline Iodine solutionBuffered methylene blue solutionEosin solutionStainning for permanent preparationSchaudinn’s fluidHeidenhain’s Haematoxilin methodTrichome stain


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Microscopic examination of wet mount


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Saline wet mount


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Iodine wet mount

• Iodine kills the organisms, therefore motility is lost.

• Used mainly to stain nuclei and glycogen mass if present.

• Flagella becomes recognisable.• Cyst can usually be specifically

identified in this method.• Lugol’s iodine solution is used.


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Lugol’s iodine• Its very strong• Must be diluted about 5 times with distilled water• Stain deteriorates quickly hence to be prepared every 2

weeks• Contains: Iodine crystals(powdered): 5 gPotassium iodide :10 gDistilled water : 10• Potassium iodide is dissolved in distilled water and iodine

crystals are slowly added. Solution is filtered and kept in a stoppered bottle of amber colour


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Buffered methylene blue wet mount

• Stains only trophozoites of amoeba

• It does not stain amoebic cyst or trophozoites and cyst of flagellates.

• Nucleus and the inclusions such as RBC or yeast cells stain dark blue

• Cytoplasm stains light blue


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Eosin wet mount

• Detection of trophozoites and cyst

• They can be much more easily detected against the pink- red background of eosin preparation


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Cover with a cover slip


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microscopic examination findings

• REMNANTS OF FOOD• vegetable cells• Muscle fibres• Starch granules• Fat globules• Connective tissue/

elastic fibres• Mineral oil or castor oil

globules

• CELLS• Epithelial cells• Pus cells• Macrophages• Ghost cells • Pyknotic bodies• Eosinophills• RBC• Crystals• Yeasts and molds• Protozoa• Helminthic parasites


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Vegetable cell

• Sometimes causes confusion with ova, eggs, cyst or cell bodies

• IRREGULAR OUTER MARGIN

Excess quantity is seen in excess intake of vegetables or indigestion


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Muscle fibres

• May confuse with Tinea segments• Excess protein intake or indigestion• Its excess excretion is called

Creatorrhoea(flesh-flow)


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Starch granules

• Variable in size, round to polygonal in shape, colourless, circular or Y shaped dot in the centre

• Confused with ova of helminths

• Found in carbohydrate dyspepsia

• Better seen in iodine preparation


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Fat globules

• Appear similar to parasitic cyst or cell bodies

• Emulsifying agents are used to eliminate confusion

• Confused with ova of helminths

• Found in fat dyspepsia


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Connective tissue/elastic fibres

• Confused with tinea segments

• Signify indigestion


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Mineral oil/ castor oil globules

• When taken as purgative• May be confused with ova of helminthes


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Epithelial cells

• Excess presence due to inflammatory conditions of colon, rectum, anal canal


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Pus cells

• Commonly found in normal stool, help to ease the passage of stool

• Normally not visible to human eye.

• If visible indicates disease• Bacillary dysentery, UC,

acute Amoebic dysentery, malignancy of rectum, drug induced enterocilitis


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Macrophages

• Large mononuclear cells with vesicular nucleus and ingested materials including RBC

• Confused with E. Histolytica cyst or E. Coli cyst

• Excess in Amoebic or bacillary dysentery


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Ghost cells

• Degerative form of macrophages, epithelial cells

• Its an enlarged/swollen eosinophilic epithelial cell with only eosinophilic cytoplasmic outline but without a nucleus

• Characteristic of bacillary dysentery


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Pyknotic bodies

• Nuclear remains of tissue cells and leucocytes

• Characteristic of acute amoebic dysentery


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Eosinophils

• In intestinal allergy• Diluting fluid used- Randolph’s diluting fluid,Pilot’s

stain• Carbol chromotrope technique• A measured quantity of the deposit is taken and

diluted with the diluting fluid 1:10 or 1: 20 according to the concentration of the residue and counted in haemocytometer.

• Increased in allergic conditions, parasitic infestation and drug allergy, ulcerative colitis


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RBCs

• seen in cases of ulcrative lesions of gut• in bacillary dysentery – yellowish discrete• Amoebic dysentery – greenish and in clumps


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Crystals • Fatty acid crystals• Calcium oxalate crystals• Triple phosphate crystals• Charcot Leyden crystals• Haemotoidin crystals• Crystals of drugs


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• Charcot Leyden crystal: • Slender and pointed at both ends,

Hexagonal bipyramidal structures localised in the primary granues of cytoplasm of eosinophils and basophils

• Evidence of parasitic infiltrate eg amoeba, ascaris, hookworm, fasciola

• diamond shaped or whetstone shaped crystals

• Normally colourless, stained purplish-red by trichome

• Vary in size and may be as large as 50 µm in length

• Found in UC, dysentery, malignant ulcers, schistosomiasis etc


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• Haematoidin crystals:• Ironless pigment derived from

haemoglobin and formed within tissues(reticuloendothelial cells) but found extracellularly after 5-7 days in foci of previous haemorrhage.

• Occurs as refractile, yellow- brown and orange-red granules

• Characteristically as rhomboid plates arranged in a radial pattern, so called hematoidin burrs.


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Yeast and molds

• Yeast are normally present

• Excess in cases of AIDS

• Molds are rare but may be seen in immunodeficiency conditions

Parasites

Stool examination by Dr. Priyanka Buragohain 80


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protozoa


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Entamoeba histolytica TROPHOZOITE STAGE • Identified by motility and

presence of ingested RBC• Shape : constantly changing

position• Size :ranges from 18 to 40 µm

,average being 20 to 20 µm• Cytoplasm :divisible in two

portion• Nucleus :spherical in shape


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RBC appear yellowish green inside the endoplasmNucleus is not visible but a faint outline may be detectedEndoplasm shows bluish or ground glass appearanceEccentric nucleus with karyosome (a small dot at the centre surrounded by a clear halo), nuclear membrane, Linen network having a spoke like radial arrangement


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PRE CYSTIC STAGE• Size :small in size,10 to 20

µm• Shape :round or slightly

ovoid with blunt pseudopodium

• Free from ingested RBC and other materials

• Nucleus : large nucleus• Retains the characteristics

of trophozoite.


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CYSTIC STAGE• Size : 6 to 9 µm / 12 to 15 µm• Shape : round, surrounded by

a highly refractile membrane called cyst wall

• Nucleus :quadrinucleate • Clear and hyaline cytoplasm• Nuclear structure retainning

the character of trophozoite


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•Iodine mounting•Body of the parasite stains yellow to light brown•Nucleus is clearly seen with a karyosome•Cytoplasm is smooth and hyaline appearance•Glycogen mass stains brown

Saline mounting•Chromatid bodies are seen as round refracile bars•Cyst wall smooth and thin•Glycogen bar not visible•Outlines of nuclei may be visible

Iron haematoxillin stain•Chromatid body and nucleus stain jet black•Cytoplasm stains bluish or greyish•Glycogen mass gets dissolved in the process of stainning and remains as a vacuole


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Entamoeba coliTROPHOZOITE STAGE• Largest amoeba 20-40 µm in diameter• Sluggishly motile• Cytoplasm not clearly defined• Opaque endoplasm packed with food

vacuoles with bacteria and others but no RBC

• Nucleus visible in unstainned preparation• In stainned prep nucleus shows large

eccentric karyosome surrounded by broader halo and coarse chromatin ranules linning nuclear membrane


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• CYST• 15- 20 µm in diameter• Rounded body• Octanucleate• Largen glycogen mass in

binucleate stage• Chromatoid body if present are in

slender filaments or pointed threads

• Glycogen mass and chromatoid bodies are absent in mature cyst


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Endolimax nana• Commensal in large intestine of

man• Trophozoites are smaller in size(8-

9 µm in diameter)• Sluggish in motility• Cytoplasmic inclusions contain

bacteria and food particles but no RBC

• Nucleus has irregular karyosome, eccentric and in contact with nuclear membrane


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CYST• Cyst are oval• Same size as the

trophozoites• Number nuclei are 1-4• Mature cyst are

quadrinucleate• Chromatoid bodies and

glycpgen mass are not seen


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Difference between different trophozoites


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Difference between different cyst


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OTHER NON PATHOGENIC AMOEBIDA SPECIES

Trophozoite of E. hartmaniTrophozoite of Iodamoeba butschlii

Cyst of blastocystis hominis


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Balantidium coli•Largest protozoal parasite•Pig is the common reservoir•Two stages•Trophozoite and encysted stage

TROPHOZOITE•Oval body•60-70 µm in length and 40-50 µm breadth •Body is covered with a delicate pellicle showing longitudinal striations•Cilia are short and delicate, of uniform length, on mouth are longer called adoral cilia•Thin layer of ectoplasm and granular endoplasm•Groove at the anterior end(peristome) leading to a mouth(cytostome) terminating in a short funnel shaped gullet(cytopharynx) extending upto 1/3rd of the body•At the posterior part permanent anus called cytophage is situated•2 nuclei: kidney shaped macronucleus, round micronucleus in the concavity of micronucleus•2 contractile vacuole, many food vacuole


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CYST• Smaller than trophic, 50-60

µm in diameter• Cytoplasm is granular

contains the macronucleus, micronucleus, refractile body

• Contractile vacuole• Thick transparent double

layered wall


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Giardia lambia• TROPHOZOITE• Flat view: a tennis or badminton racket• Side view: longitudinally split pear• Dorsal surface is convex and the ventral surface

in concave with a sucking disc• Size is 14 × 7 µm• Anterior end is broad and rounded, posterior

end tapers to a sharp point• Bilaterally symmetrical and all organs are

paired.• 2 axostyles, 2 nuclei, 4 pairs of flagella

Exist in 2 phase: trophozoite and cyst


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CYST• Oval in shape• Size is 12 × 7 µm• Axostyle lie diagonally like dividing wall

within the cyst wall• 4 nuclei lie clustered at one end, lie in pairs

at opposite poles• Remains of flagella and sucking disc may be

seen in cytoplasm• Acid causes the parasite to encyst


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What we can see in microscopic

examination of stool ?ADULT WORM

LARVA

OVA

CYST


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HELMINTHES

PLATYHELMINTHES NEMATHELMINTHES

CESTODETREMATODE

NEMATODE

TAPEWORMTaenia soliumTaenia saginataECHINOCOCCUS

G. HominisF. BuskiF. HepaticaC. SinensisP. westermani • A. Lumbricoids

• T. Trichiura• A. Duodenale• E. Vermicularis•S. Stercoralis


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ADULT WORM• TAENIA SAGINATA/SOLIUM• DIPHYLLOBOTHRIUM• HYMENOLEPIS• DYPILIDIUM

LARVAL STAGE• ECHINOCOCCUS: Hydatid

cyst• SPIROMETRA• HYMENOLEPIS• TAENIA SOLIUM• MULTICEPS:


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Taenia solium• Segments of Tape worm or single

segment may be found• White in colour, semi transparent.• May be 3 – 10 m long/ 1-3 cm

segments maybe upto 24 m• Variable length(1000-2000

proglottids)• When stool is allowed to dry up the

pieces of segments will roll upand appear as round worm, moistening the segments will restore the shape

• Head is quadrate in outline, has 4 circular suckers

• Head is absent of rostellum/hooklets


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Eggs of T. saginata• Spherical and brown in colour• 31-43µm in diameter• Thin outer transparent

shell(remnants of yolk mass), causes egg to clump together

• Inner embryophore is brown, thick walled, radially striated

• Contains an oncosphere(14-20µm), with 3 pairs of hooklets

• Doesnot float in saturated solution of common salt


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Taenia solium

• 2-3 metres long(800-900 proglottides)

• Scolex is 1mm in diameter, globular in outline, 4 circular suckers,

• Head with rostellum armed with a double row of alternating large and small hooklets, shaped like daggers or Arabian poniards

• Segments are shed in chains of 5-6 at a time, not single.


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• EGGS• Same as T. Solium• 30x40 µm sized egg• Pale yellow• Thick radially striated

embryophore with 6 hooklets inside


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Echinococcus granulosus• Commonly called dog

tapeworm/ hydatid worm• Man harbours the larval form,

not the adult• Larva found wiyhin the hydatid

cyst, scolex of the future adult worm remains invaginated within a vesicular body.


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Hymenolepis diminuta


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Gastrodiscoides hominis• Prevalent in Assam and Bengal• Pyriform in shape• Measures 5-10 mm × 4-6 mm• Body has 2 parts: anterior conical and

posterior hemispherical portion which is hollowed out ventrally to form a concave disc

• Acetabulum is postero terminal, situated ventrally

• Notch at posterior end• Eggs are ovoid, operculated, 130×60

µm, immature when oviposited


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Fasciola hepatica• Eggs • Large, operculated, ovoid , brownish

yellow(bile stained)• Size is 140× 80 µm• Contains a large unsegmentad ovum in a

mass of yolk cells• Excreted with bile into duodenum and

then passed out along with the faeces• Does not float in saturated common salt

sol.• Can develop only in water


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Fasciola buski• Reported in Assam, bengal, china,

thailand and other oriental regions

• Largest trematode(2-7.5 length, 8-20 mm bredth, 0.5-3 mm thickness)

• Elongated and oval in shape• Resembles F. Hepatica but does

not possess any cephalic cone• Each worm lay 25,000 eggs per

day• Eggs are indistinguishable from F.

hepatica


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Clonorchis sinensis

EGGS• Yellowish brown• Flask shaped• Operculated• Possess a terminal hook like

spine(resembling an electric bulb)• Small in size(35×20µm)• Ciliated embryo (oviposited stage)• Do not float in saturated solution

of common salt


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Paragonimus westermani

• Golden brown in colour• Oval in shape with flattened

opercula• 80- 55 µm• Each egg contains an

unsegmented ovum surrounded by yolk cells

• Prevalent in Assam• Found in sputum and faeces


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Ascaris lumbricoids

• Large round worms may be males and females or both

• Pinkish in colour• 0.3-0.4 cm in thickness• 15-25 cm long• Males are shorter than

females• Have curved tapering tail


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• UNFERTILISED EGGS• Do not float on floatation method• Size- 40×70 µm• Yellow in colour• Elongated• Mammilated thin shell, ovum

containing refractile yolk globules occupying the whole inside space

• May be confused with veg cell

• FERTILISED EGGS• Float on floatation method• Size- 40×70 µm • Yellow in colour• Oval or round• Thick mammillated coat and

single celled ovum inside


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Enterobius vermicularis• Small round worm or thread

like worm or pin worm(spindle shaped)

• White coloured• 0.5-1 cm long• Tail pointed• Males smaller than females

and posterior body is curved and sharply truncated(found only after purgation)


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• EGGS• Colourless(not bile

stained)• 20×50 µm• Assymetrical, Oval

planoconvex, • thin transparent

shelled, • contain coiled tadpole

likelarva inside• Floats in saturated salt

solution

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Ancylostoma duodenale

• Hook worm• Small greyish white or pink coloured

cylindrical• 1-1.5 cm long• One end is curved like a hook• 6 teeth, 4 hook like on ventral surface

and 2 knob like on the dorsal surface



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EGGS• Oval or elliptical in shape• 40x60 µm sized egg• Colourless(not bile stained)• Surrounded by a

transparent hyaline shelled membrane

• Contains 4 segmented ovum inside.

• Floats on saturated solution of salt


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Trichuris trichiura

• Whip worm• Looks like a tiny whip

with a handle and a lash• 3-5 cm in length• White coloured


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• 25x50 µm sized egg• Brown coloured• Double shelled, outer

one is bile stained• Thick shelled, barrel

shaped with mucus plug at both pole

• Single ovum• floats in saturated

solution of common salt


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Strongyloids stercoralis

• Adult worm:• Females are readily

discovered than males• 2.5mm ×40-50 µm (females)• Posterior extrimity is pointed • Males are shorter and

broader than females


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• Eggs• Eggs are conspicuous within the body in a

single line• 55-30µm• Thin shelled• Transparent, oval• Contain larva ready to hatch. It is the larva not

the eggs are found in stool.


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• Rhabditiform larvae• Develop directly from

gravid females• Short mouth, double-

bulb oesophagus

• Filariform larvae• Longer and slender• Short mouth and

cylindrical oesophagus


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Helminthes that float/do not float on saturated solution of saline

Eggs that float• A. Duodenale• N. Americanas• E. Vermicularis• H. Nana• A. Lumbricoids• T. Trichuria• H. Diminuta

Eggs that do not float• A. Lumbricoids• T. solium• T. Saginata• Trematodes• F. Buski• F. Hepatica• C. Sinensis


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Plant hairs can be confused for larvae oh hookworm or Strongyloides stercoralisPlant hair resembling S. strongiloids


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Parasite of earth worm

Pollen grain resemblening to fertile egg of A. lumbricoids

Bee pollen resembling t. Trichuria egg


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STOOL CULTURE

• Used to detect the presence of disease causing(pathogenic )bacteria

• Help to diagnose an infection of digestive system

• Used in conjunction with stool test• Reference range for stool culture is negative


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Most common bacteria for culture of stool

• Campylobacter species• Salmonella species• Shigella species• Yersinia species• Vibrio species(travel history)• Some bacteria cause illness by producing toxins(PCR,

Antigen test are to be done with stool test)• Escherichia coli• Clostridium difficile


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Collection

• Specimen collected via rectal swab(in infants)• Sterile collection container not required• No detergent or preservative should be present in the

container• Specimen should be immediately transported to the

laboratory• If transport is delayed by longer than 2 hours, transport

media(eg Cary- Blair) is recommended• Samples must be sent in a sealed, leak-proof container

marked with a biohazard sticker


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Medias used commonly

• MacConkey agar- Salmonella species, shigella species

• Eosin methylene blue agar• Triple sugar iron(TSI)- differentiate salmonella

and shigella• Sabouraud agar• Hekteon enteric agar• Selenite broth


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Summary • Definition of stool• Composition of stool• Precaution and collection of

sample• Physical examination• Chemical examination• Microscopic examination• Artifacts • Stool culture

THANK YOU !!!Stool examination by Dr. Priyanka

Buragohain 139

Health & Medicine

Routine examination of stool