Para Lab 3

• SIGNIFICANCE OF GROSS EXAMINATION

  1. Can be helpful in the presumptive diagnosis of several intestinal disorders. Careful observation of the color of the stool is an important part of preliminary diagnosis.
  2. Provides the opportunity to recover tapeworm proglottids or adult roundworms (Ascaris or Enterobius from the surface of the specimen or in the container).
• Normal Color – light brown to dark brown due to bacterial degradation of bile pigments into stercobilin. * Blood is an abnormal finding in the stool.
• Consistency of Stool Specimen

  1. Hard, small, firm, spherical masses, scyballous - constipation; atony of the colon
  2. Formed - maintains shape, can be punctured.
  3. Semi-formed -bottomside flattens in container
  4. Soft - can be cut with an applicator stick.
  5. Mushy - can be reshaped with an applicator stick. Fluffy pieces w/ pudding-shaped consistency
  6. Loose- stool shapes to the container.
  7. Diarrheic - stool will flow slowly out of the container.
• Consistency of Stool Specimen

  8. Watery - fluid-like stool; pours out of the container.

  9. Narrow-ribbon like - spastic bowel or rectal stricture, narrowing or obstruction of lower colon; tumor.

  10.Sticky,black,tarry - upper GIT hemorrhage

  11. Rice-watery - Cholera

  12. Pea-soup - Typhoid

  13. Large caliber stool - Hirschsprung disease (congenital aganglionic megacolon, enlargement of the colon)
• Odor:

  • Derives from indole and skatole degradation products of proteins.
  • Not included in the gross examination of stool
• Various structures may be mistaken for protozoan cysts or worms by beginners.

  1. Epithelial cells and macrophages can be confused with amoebic trophozoites, especially macrophages that show slight amoeboid movement and may contain red blood cells. The nuclei which can be seen in BMB (Buffered Methylene Blue) stained mounts, appear much larger than nuclei of amoeba and usually contain several granules or particles of chromatin.
• Pus cells can be confused with amoebic cysts. The nuclei appear as 3 or 4 rings and usually stain heavily. The cytoplasm is ragged and the cell membrane is often not seen. Amoebic cysts have a distinct cell wall.
• Hair and fibers may be confused with larvae. However, hairs and fibers do not have the same internal structure as larvae
• Plant cells (e.g. molds or yeast) can be confused with cyst or eggs. Plant cells usually have a thick wall; cyst has a thin wall. Yeast and molds are usually smaller than amoebic cysts and do not have nuclei such as seen in amoebic cysts
• Eggs of arthropods and plant nematodes may be mistaken as parasites
• Patients who have been treated for protozoan infections are typically checked 3 to 4 weeks after therapy. A patient treated for helminth infection may be checked 1-to-2-week post therapy and checks for Taenia may be delayed for 5 to 6 weeks post therapy
• Refrigeration at 4-8 C preserves protozoan trophozoites for several days and cysts for several weeks.
• Formalin is an all-purpose fixative. A 5% concentration is recommended for protozoan cyst while a 10% concentration is recommended for helminth eggs and larvae. However, protozoan trophozoites are destroyed. Preserved stool can be concentrated using Formalin-Ether or Formalin-Ethyl Acetate Concentration Technique (FECT).
• Schaudinn’s Solution is frequently used for fixation of fresh fecal material. It is used for preparing permanent-stained smears to demonstrate intestinal protozoa. Although it is less effective than PVA, it is still very useful when PVAis unavailable. The greatest problem in this fixative is that it contains mercuric chloride which is highly toxic to humans. Problems of mercury disposal may therefore arise.
• Polyvinyl Alcohol (PVA) is an excellent fixative for preservation of morphologic features of intestinal protozoa, in particular trophozoite stages, as well as helminth eggs and larvae. PVA technique utilized a plastic resin mixed with stool in a ratio of 3 parts PVA to 1 part stool. Samples fixed with PVAcan be best stained either immediately or weeks or months later. Well-fixed specimens will remain stable for a year or longer. However, it may distort slightly their cysts.
• Merthiolate-Iodine-Formaldehyde (MIF) is a combination of preservative and stain for fecal specimens. It is especially useful in field surveys. It preserves all stages of helminthes and protozoa as well as stains protozoans for better identification. However, care must be exercised in removing fecal material from the MIF sample to avoid taking up too much liquid. Furthermore, iodine component of the fixative is unstable and not applicable for concentration procedures.
• Sodium-Acetate Formaldehyde (SAF) is an alternative to Schaudinn’s because of the concern surrounding the use of mercuric chloride. SAF contains 10% formalin as a fixative plus sodium acetate, which acts as a buffer.It is easy to prepare and store, eliminates the use of mercuric compounds, can be used for concentration and permanent smears and does not interfere with monoclonal antibody studies. It also aids in the recovery of protozoan cysts and trophozoites, helminth eggs and larvae and intestinal coccidians.
• 10% Formalin (for wet mount) – prepare a mixture containing 1 part of stool to 3 parts of formalin solution. Place in a vial; crush the stool thoroughly. It preserves specimen indefinitely if the bottle is tightly closed.
• MIF (for wet mount) – just before dispatching, mix in a tube or vial 4.7 ml of MIF solution and 0.3 ml of Lugol’s iodine solution. Add a portion of stool, approximately 2 ml. Crush with a glass rod or stick. It preserves specimen indefinitely.
• PVA (for permanent staining) – in a bottle or vial, pour about 30 ml of PVAfixative or 3 quarters full; add enough fresh stool to fill the container. Break the stool with a stick and cover. It preserves all forms of parasites indefinitely.
• Color of Feces

  A) Black

  B) iron

  C) bismuth

  D) charcoal

  E) Bleeding upper Gastrointestinal Tract

  F) Gray

  G) Chocolate

  H) cocoa

  I) Steatorrhea

  J) mushy/frothy

  K) Very light gray

  L) milk products

  M) Barium

  N) Bile duct obstruction

  O) Jaundice

  P) Green or Yellow Green

  Q) spinach

  R) vegetable

  S) unchanged or presence of biliverdin

  T) Red

  U) beets

  V) Bleeding lower Gastrointestinal tract

  W) Yellow

  X) Starchy foods

  Y) Bilirubin

  Z) Clay

  [) None

  \) Absence of diminution of bile

  ]) bile

  ^) salts

  _) BaSulfate