b. Quantity. A normal fecal daily output varies considerably, but usually is within
the range of 100 to 200 grams for an average adult. The amount of feces depends on
the type of food consumed and the water content of the stool. Vegetable diets
considerably increase the quantity passed per day. Since the quantity of fecal specimens
varies considerably and usually only random samples are sent to the parasitology section
for examination, the quantity becomes an unimportant factor and is of no consequence.
c. Odor. Diet and degree of digestion are factors affecting the odor of a given
sample. The normal offensive odor is due to indole, skatole, and butyric acid production.
Stools from an individual who is on a meat diet have more of an odor than specimens
collected from a person on a vegetable diet. An extremely foul odor is usually caused by
the action of bacteria on undigested protein--such stools are normally alkaline in pH. A
putrid odor is associated with lower bowel disorders. A rancid or sour smell is often
associated with incomplete digestion, absorption of carbohydrates, gas fermentation, and
the presence of fatty acids.
d. Color. All the components of the stool specimen contribute to its color. The
normal light or dark brown color is due to the reduction of bilirubin and other bile
constituents. Chocolate brown is usually due to excessive color contributed by the
consumption of cocoa, chocolate, coffee, blackberries, and cherries. A black or tarry
stool may be caused by medications that include iron, bismuth, and charcoal. A dark
color may also be due to digested blood as part of the diet or from bleeding in the upper
part of the tract. Red color may be due to excess amounts of tomatoes or beets in the
diet; however, a bright red color may indicate bleeding in the lower intestinal tract. A gray
color is usually due to the abundant presence of fats or to deficiency of bile components.
A yellow color may be present due to unchanged bilirubin or to the consumption of milk,
cornmeal, rhubarb, or certain medications. The specimen may be green due to
unchanged biliverdin, the consumption of spinach, or the use of calomel.
e. Mucus. Mucus may normally be present in stool in small amounts. Mucus in
an abnormal amount, readily visible as small white areas, is usually indicative of intestinal
irritation. If the site of the intestinal irritation is located in the small intestine, the mucus is
usually found on the outside surface of the specimen. This should be reported even if not
f. Leukocytes (Pus Cells). Few leukocytes are normally present in feces. In
dysentery and in inflammatory or ulcerative conditions, the number of pus cells is
increased considerably. The observation of these cells is aided by adding one or two
drops of 10 percent acetic acid to a drop of the fecal emulsion. This makes the nuclei of
the leukocytes more prominent. Reporting leukocytes is usually done by giving the
average range of leukocytes per high power field.