Go Cal | Microscopic examination of feces
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Feces (synonym: feces, feces, feces) - this is the contents of the large intestine secreted during defecation.

The feces of a healthy person consist of about 1/3 of food debris, 1/3 of the discharge of the digestive organs and 1/3 of the microbes, 95% of which are dead. The study of feces is an important part of the examination of a patient with diseases of the digestive organs . It can be general clinical or pursue a specific goal - the detection of hidden blood, worms eggs, etc. The first includes macro, microscopic and chemical research. Microbiological examination of feces produced in case of suspected infectious intestinal disease. The feces are collected in a dry clean dish and examined fresh, no more than 8-12 hours after discharge, while maintaining in the cold. The simplest are looking for a completely fresh, still warm feces.

For microbiological examination, feces must be collected in a sterile tube. In the study of feces for the presence of blood, the patient should receive food in the preceding 3 days without meat and fish products.

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When studying the state of food digestion, the patient receives a common table (No. 15) with the obligatory presence of meat in it. In some cases, for a more accurate study of the assimilation of food and exchange resort to a trial diet. Before collecting feces for 2-3 days, the patient is not given drugs that change the nature or color of feces.

Macroscopic examination of feces means its quantity, consistency, shape, color, smell, the presence of visible food residues, pathological impurities, parasites .

The amount of feces per day (normally 100–200 g) depends on its water content, the nature of the food, and the degree of its absorption. With the defeat of the pancreas, amyloidosis of the intestine, sprue , when the absorption of food is broken, the weight of feces can reach up to 1 kg.

The form of feces largely depends on its consistency. Normally, its shape is sausage, the consistency is soft, with constipation the feces consist of dense lumps, with spastic colitis it has the character of “sheep” feces - small dense balls, with accelerated peristalsis the feces are liquid or mushy and unformed.

The color of normal feces depends on the presence of stercobilin in it (see).

In violation of the secretion of bile feces acquires a light gray or sand color. With heavy bleeding in the stomach or duodenum, the feces are black (see Melena). Some medications and pigments of plant foods also change the color of feces.

The smell of feces is noted if it differs sharply from the usual (for example, a putrid odor with a decaying tumor or putrid dyspepsia).

For better detection of food debris, the feces are triturated with a 10-fold amount of water and examined in a Petri dish on a black background. The fat in this emulsion floats as a hazy bloom on the surface. With an abundance of fat ( steatorrhea ), the feces have an oily consistency and a lighter color. From the pathological components of feces you can see mucus, blood, pus, appearing during inflammatory and ulcerative processes in the large intestine, concrements (biliary, pancreatic and intestinal) and parasites - round worms, ribbon segments.

microscopic examination of feces
Fig. 1. Muscle fibers (native preparation): 7 —fibers with cross-striation; 2 - fibers with longitudinal striation; 3 — fibers that have lost bandwidth.
Fig. 2. Undigested plant fiber (native drug): 1 - fiber cereals; 2 - fiber of vegetables; 3 - plant hairs; 4 - vessels of plants.
fecal microscopy
Fig. 3. Starch and iodophilic flora (stained with Lugol solution): 1 - potato cells with starch grains in the amidulin stage; 2 - potato cells with starch grains in the erythrodextrin stage; 3 - extracellular starch; 4 - iodophilic flora.
Fig. 4. Neutral fat (color Sudan III).
feces
Fig. 5. Soaps (native drug): 1 - crystalline soaps; 2 - clumps of soap.
Fig. 6. Fatty acids (native drug): 1 - fatty acid crystals; 2 - neutral fat.
feces under the microscope
Fig. 7. Mucus (native drug; small increase).
Fig. 8. Potato cells, blood vessels and plant fiber (native drug; low magnification): 1 - potato cells; 2 - vessels of plants; 3 - vegetable fiber.

Microscopic examination (Fig. 1-8) is carried out in four wet preparations: on a glass slide a lump of feces is rubbed the size of a match head with tap water (first preparation), lyugolevsky solution (second preparation), solution of Sudan III (third preparation) and with glycerin (fourth drug). In the first preparation, most of the fecal elements of the feces are differentiated: indigestible plant fiber in the form of cells of different size and shape with a thick shell or their groups, digestible cellulose with a thinner membrane, muscle fibers of yellow color, cylindrical shape with longitudinal or transverse striation (undigested) or without striations (semi-digested); erythrocytes , leukocytes , cells of the intestinal epithelium , mucus in the form of light cords with vague outlines; fatty acids in the form of fine needles, pointed at both ends, and soap in the form of small rhombic crystals and lumps. The drug with lyugolevskim solution is prepared for the detection of starch grains stained with this reagent in blue or purple color, and iodophilic flora. In a preparation with Sudan III, bright, orange-red drops of neutral fat are found. The drug with glycerin is used to detect helminth eggs.

Normally, feces contain indigestible cellulose, single scraps of muscle fibers without transverse banding, single drops of fat, and some soaps. The presence of starch indicates insufficient digestion of carbohydrates , an increase in the number of muscle fibers (creatorea), and the appearance of cross-striated ones — a poor digestion of proteins; with poor digestion of fats, not only a lot of neutral fat appears in the feces, but (with a lack of bile) a lot of fatty acids and soaps. Of the parasites in the feces can be found protozoa - amoeba, balantidii, Giardia, Trichomonas, as well as worms and their eggs (see. Helminthological research methods).

Chemical research in general clinical analysis is reduced to simple high-quality samples. Using litmus paper to determine the reaction environment. Normally, it is neutral or slightly alkaline. When the feces are light-colored, they are tested for stercobilin : a lump of feces the size of a hazelnut is ground with a few milliliters of a 7% solution of mercuric chloride and left for a day. In the presence of stercobilin, pink staining occurs.

Determination of hidden blood is the most important study to identify the ulcer or tumor process in the gastrointestinal tract. For this purpose, a benzidine sample is used (see), a guaiac test (see).