PARA LAB M2

• brown: normal or stercobilinogen
• black and tarry: bleeding upper GI tract (proximal to cecum) and drugs (iron salts, bismuth salts, charcoal)
• red: lower GIT bleeding/tumors, inflammatory process, anal fissure, hemmorhoids, tumors, undigested tomatoes or beetroot
• yellow or yellow-green: diarrhea
• clay colored (gray-white): bilary obstruction
• silvery: carcinoma of ampulla of Vater
• watery: certain strains, escherichia coli, rotavirus enteritis, cryptosporidiosis
• rice water: cholera
• unformed with blood, mucus, and pus: bacillary dysentery, ulcerative colitis, intestinal tuberculosis, amoebiasis, enteritis
• unformed, frothy, foul smelling, which float on water: steatorrhea
• pale color stool with greasy appearance: pancreatic deficiency due to malabsorption
• stool odor: indole and skatole which are formation by bacterial fermentation and putrefaction
• foul odor: undigested protein and by excessive intake of carbohydrate
• sickly odor: undigested lactose and fatty acids
• hard = resists puncture

  formed = can be punctured

  soft = can be cut with applicator stick

  mushy = can be reshaped

  loose = shapes to container

  diarrheic = flows

  water, liquid = pours

  dysenteric = contains gross blood and mucus, with or without pus, not coded for consistency
• mucus with blood clinging to stool is seen in: lower GIT malignancy and inflammatory lesions in anal canal
• benzidine and orthotolidine are carcinogenic and are no longer used
• Principle for occult blood

  • hemoglobin has peroxidase-like activity and releases oxygen from hyderogen peroxide
  • oxygen molecule then oxidized the chemical reagent to produce a colored reaction
• benzidine test is also highly sensitive and false-positive reactions are common
• trace = very faint blue

  + = faint blue

  ++ = distinct blue

  +++ = dark blue

  ++++ = prussian blue
• preparation of slides

  • drop of normal saline is placed near one end of a glass slide and a drop of Lugol iodine solution is placed near the other end
• saline wet mount is used for demonstration of eggs and larvae of helminths, and tropozoites and cysts of protozoa and can also detect red cells and white cells
• iodine wet mount is useful for identification of protozoal cysts as iodine stains glycogen and nuclei of cysts
• increased number of WBCs in stool is associated with:

  • bacillary dysentery
  • chronic ulcerative colitis
  • shigellosis
  • salmonella infections
  • invasis e-coli infections
  • anal or rectal fistula
  • localized abscess
  • amoebiasis and typhoid
• bright red stool is seen in cases of lower GIT bleeding
• what can be seen in bacillary dysentery and ulcerative colitis?

  macrophages
• what can be seen in inflammatory conditions of the bowel?

  epithelial cells
• how many stool cultures should be collected if the patient's clinical picture suggests bacteril involvement, despite previous negative cultures?

  at least 3
• meat or muscle fibers: these presence of artefacts show impaired intraluminal digestion
• pollen grains in stools are mistaken for larvae eggs?

  false
• what artefact is shown?

  pollen grain

  
• what artefact is shown?

  charcot-leyden crystals

  
• what artefact is shown?

  air bubbles

  
• what artefact is shown?

  plant fiber

  
• what artefact is shown?

  plant cell

  
• what is this?

  macrophages

  
• Chemical examinations

  • Fecal occult blood - inflammatory bowel disease and neoplasms
  • Fecal pH, test for reducing sugar - carbohydrate malabsorption
  • Sudan stain and estimation of fecal fat - fat malabsorption
  • Fecal urobilinogen - liver disease
  • Fecal osmotic gap - distinctio between secretory and osmotic diarrhea
• Microscopic examinations

  • Direct wet mount - eggs/larvae of helminths and cysts/trophozoites of protozoa
  • Special stains

  = Trichome stain - trophozoites and cysts

  = AFB stain - oocysts of cryptosporidiu, cyclospora, and isospora

  = Wright’s stain - WBCs

  • Cellophane technique - eggs of Enterobius vermicularis
• Reference ranges

  • Bulk - 100-200 g/day
  • Color - brown
  • Water - up to 75%
  • pH - 7-7.5
  • RBCs - absent
  • WBCs - few
  • Epthelial cells - present
  • Crystals - calcium oxalate and triple phosphate
• Causes of false positive tests?

  • ingestion of peroxidase containing foods like red meat, fish, poultry, turnips, horseradish, cauliflower, spinach, or cucumber. Diet should be free from peroxidase containing foods for at least 3 days prior to testing
  • drugs like aspirin and anti-inflammatory drugs, which increase blood loss from gastrointestinal tract in normal persons