(4) Sigmoidoscopic examinations. When amebiasis is suspected and stool
samples are negative, material for examination may be collected by sigmoidoscopy. The
procedure should be performed after a normal bowel movement or two to three hours
after administration of a cathartic. The specimen is collected with a pipette rather than
with a swab by aspirating material from any visible lesion and from the mucosa.
Examination of sigmoidoscopic material should be done immediately, but fixation can be
done with polyvinyl alcohol (PVA) after the wet preparation.
(5) Liver abscesses. Exudates aspirated from the liver may contain cysts and
trophozoites of Entamoeba histolytica. The first portion of the specimen does not usually
yield organisms, but the second (reddish) portion does. Aspirates should be examined
microscopically with wet preparations as well as with permanent stains.
2-16. MACROSCOPIC EXAMINATION
Feces consist of food remnants, various products of digestion, nonpathogenic
organisms, and possibly pathogenic organisms. Consistency, quantity, odor, color, and
contents of a stool specimen depends on the health and diet of the individual. The direct
observation of the fecal specimen may detect a pathogenic process that will not be
detected by any other method.
a. Consistency. Normally, stool is soft and formed, retaining the bowel cast.
Under abnormal conditions, other densities may be detected.
Dry and hard. This is an indication of constipation and/or dehydration.
(2) Ribbon-like. Stool excreted in this manner may be found in spastic colitis,
obstruction, or stricture of the rectum and anus.
(3) Mushy. Mushy stool is unformed (but not to the point where it flows
readily when the container is tilted); however, the feces does not remain in the bowel
cast. Stools of this sort include the "fluffy" stools which may be caused by trapped gas as
in patients with sprue or from excessive carbohydrate fermentation.
(4) Semi-liquid. These stools are characterized as slowly flowing upon tilting
the container. Included in this category are the stools found in diarrhea, dysentery, or
(5) Liquid. These are diarrheic stools that consist mainly of water. They
readily flow upon tilting the box.