1. First, do general trait inspection
When inspecting the stool, the examiner must first observe the stool specimen with the naked eye, and usually make a preliminary diagnosis based on the stool characteristics.
1. To understand the amount of stool. Normal people usually have a bowel movement once a day, the amount is about 100~300g, which varies with the amount of food consumed, the type of food and the functional state of the digestive organs. Those who eat fine grains and meat-based foods will have fine and small stools. Those who eat coarse grains and eat more vegetables will increase the amount of feces due to more fiber. When the stomach, intestines, and pancreas have inflammation or dysfunction, the amount of stool increases due to inflammation, exudation, increased secretion, hyperintestinal peristalsis, and poor digestion and absorption.
2. Color and character The stool of a normal adult is yellowish-brown cylindrical soft stool when it is discharged, and the stool of a baby is yellow or golden yellow mushy stool. After prolonged placement, the porphobilinogen in the stool can be oxidized, which can cause the color to darken, and the pathological changes can be seen as follows:
2.1 Slurry or watery stool: It is often caused by intestinal hypermotility or excessive secretion of intestinal mucosa. Seen in various infectious and non-infectious diarrhea, especially acute enteritis, catharsis and hyperthyroidism. In children with enteritis, the bowel movement is accelerated, and the stool is green and mushy. Pseudomembranous enteritis is seen when a lot of yellow-green loose juice-like stools and membranous material are included. When AIDS patients are infected with intestinal cryptogown worms, they can excrete a large amount of watery feces. Vibrio parahaemolyticus is food poisoning and discharges watery stools. Hemorrhagic necrotizing enteritis discharges red bean soup-like stool.
2.2 Mucus stool: A small amount of mucus in normal stool is not easy to detect because it mixes evenly with stool. If there is mucus visible to the naked eye, the amount has increased. When the small intestine is inflamed, the increased mucus is evenly mixed in the stool; when the large intestine is diseased, because the stool has gradually formed, the mucus is not easy to mix with the stool; the mucus from the rectum is attached to the surface of the stool. The mucus of simple mucus stool is colorless and transparent, slightly viscous, while purulent mucus stool is yellow-white and opaque. It is found in various enteritis, bacillary dysentery, and amoebic dysentery.
2.3 Purulent and purulent stools: When there are lesions in the lower part of the intestine, such as dysentery, ulcerative colitis, localized enteritis, colon or rectal cancer, it often manifests as purulent and purulent stools. The amount of pus or blood depends on the type of inflammation and its The degree of amoebic dysentery is mainly blood with pus in the blood, which is dark red and dilute jam-like. Bacterial dysentery is mainly mucus and pus, with blood in the pus.
2.4 Frozen stools: Patients with irritable bowel syndrome often discharge sticky, membranous or tie-like objects after abdominal cramps. Some patients with chronic bacillary dysentery can also discharge frozen stools.
2.5 Bloody stools: Bloody stools can be seen in rectal polyps, rectal cancer, anal fissures and hemorrhoids. Hemorrhoids often have blood dripping after defecation, while other diseases have blood attached to the surface of the stool.
2.6 Black stool and tarry stool: The formed black stool is called black stool, thin, thick, dark, shiny stool, and it is called tarry stool. Seen in gastrointestinal bleeding, red blood cells are digested and destroyed by the gastrointestinal juice to become heme, porphyrin and iron sulfide, the latter stimulate the small intestine to secrete excessive mucus. Upper gastrointestinal bleeding 50ml～75ml may cause melena, and the occult blood test shows a strong positive reaction; if it is tarry stool and lasts for 2 to 3 days, it means that the bleeding volume is at least 500ml. Black stool can also be discharged after taking activated charcoal, iron, etc., but it is dull and the occult blood test is negative. If you eat more animal blood, liver or oral iron, the stool can also be black, and the occult blood test can also be positive. Pay attention to distinguish .
2.7 White clay-like stool: It is seen in bile duct obstruction caused by various reasons, which reduces or lacks bilirubin entering the intestinal tract, resulting in a corresponding reduction or lack of fecal bilirubin. After barium meal gastrointestinal radiography, the stool may appear white or yellowish white due to the discharge of barium sulfate.
2.8-meter swill-like stool: The stool is white rice-washed water, containing mucus pieces, and it is large and watery. It is seen in patients with severe cholera and paracholera.
2.9 Thin strips of stool: discharge of thin strips or flat pieces of stool, suggesting rectal stenosis, more common in rectal cancer.
2.10 Sheep feces: The feces are dry and hard and are spherical or sheep feces. Sometimes the feces balls accumulate into sticky stools. Often due to habitual constipation, feces stay in the colon for a long time; it is caused by excessive absorption of water, which is more common in the elderly and those who have weak bowel movements in postpartum women.
2.11 Milk curd: Yellow-white milk curd is seen in the stool of infants, and egg-flower soup-like stools can also be seen, suggesting insufficiency of fat or casein. It is common in infants with indigestion and infant diarrhea.
3. Smell Normal feces are smelly due to protein decomposition products, such as indole, skatole, mercaptans, hydrogen sulfide, etc. It is heavy for meat eaters and light for vegetarians. There is a foul odor when suffering from chronic enteritis, pancreatic disease, colon or rectal cancer ulceration. Amoebic enteritis stool is bloody and smelly. Stool smells sour when fat and carbohydrates are not digested or absorbed.
4. Parasites Larger organisms such as roundworms, pinworms and tapeworms or their fragments can be distinguished by naked eyes. Hookworms must be seen by washing the feces through a sieve. After taking the insect repellent, check the feces for the presence of worms, and carefully look for the head section after repelling the tapeworm.
5. Calculus Gallstones, pancreatic stones, stomach stones, fecal stones, etc. can be seen in the stool. The most important and common one is gallstones, which are common after the application of stone-eliminating drugs or lithotripsy.
2. Microscopic examination is very important
Normally, normal saline is used to directly smear the film (the iodine solution method can be used when checking the amoeba cyst). After the smear is covered with a cover glass for microscopic examination, carefully search for cells, parasite eggs, bacteria, protozoa, and observe various Food residue to understand the digestion and absorption function.
1.1 White blood cells: neutrophils are common, not seen or occasionally seen in normal stool. Increased in intestinal inflammation, the number of white blood cells is generally less than 15/HP during small intestinal inflammation, and the cells are not easy to identify due to partial digestion. In the case of colon inflammation, such as bacillary dysentery, a large number of white blood cells can be seen, and even the field of vision can be seen. The structure of some white blood cells is destroyed, the nucleus is unclear, and the piles are called pus cells. Some cell bodies swell up and swallow foreign body residues, called small phagocytes. In allergic enteritis, intestinal parasitic diseases (such as hookworm disease), more eosinophils can be seen in the stool.
1.2 Red blood cells: There are no red blood cells in normal stool, and inflammation or bleeding in the lower intestine can occur, such as dysentery, ulcerative colitis, colorectal cancer, and rectal polyps. In bacillary dysentery, red blood cells are less than white blood cells, and they are scattered and normal in shape. In amebic dysentery, there are more red blood cells than white blood cells, which are mostly piled up and fragmented.
1.3 Large phagocyte: a monocyte that swallows larger foreign bodies; the cell body is larger than neutrophils, round, oval or irregular, with irregular nuclei, with 1 to 2 nucleoli. They vary in size and often have pseudopod-like protrusions in the cytoplasm, containing phagocytic particles and cell debris. Seen in bacillary dysentery and rectal inflammation.
1.4 Intestinal mucosal epithelial cells: columnar epithelial cells, oval or short columnar, with rounded ends. A small amount of columnar epithelial cells that fall off under physiological conditions are mostly destroyed; therefore, they cannot be seen in normal stool. During colon inflammation, epithelial cells increase and are often interspersed between white blood cells. Pseudomembranous enteritis is more common in small pieces of fecal mucosa, and a large number of viscous secretions are present.
1.5 Tumor cells: Take bloody stool of patients with sigmoid colon cancer and rectal cancer for staining in time, and piles of cancer cells may be found.
2. Food scraps
Food residues in normal feces are digested amorphous fine particles. Only occasional food residues such as starch granules and fat droplets that are not fully digested can be seen.
2.1 Starch granules: round or oval granules of different sizes with a special wheel-like structure, dyed blue after dripping with iodine solution, reddish brown if partially hydrolyzed. Diarrhea is easy to see in the stool of people with chronic pancreatitis and pancreatic insufficiency, due to carbohydrate indigestion, it can appear in large amounts in the stool.
2.2 Fat droplets: Neutral fat taken by normal people is mostly absorbed after digestion and decomposition by pancreatic lipase, and it is rarely seen in feces. In acute and chronic pancreatitis and pancreatic cancer, due to lack of lipase, or due to intestinal hypermotility, diarrhea, dyspeptic syndrome, etc., fat droplets increase, stool volume increases, foamy, off-white, shiny, and foul-smelling.
2.3 Muscle fiber: The meat that is eaten daily is mainly animal striated muscle, which mostly disappears after digestion and decomposition by protease. A small amount of muscle fibers can be seen after a large amount of meat, and there should be no more than four in a cover glass. They are light yellow strips, flakes, and thin horizontal stripes. When eosin is added, they can be dyed red. Increase in bowel hypermotility, diarrhea, and decreased pancreatic exocrine function. Sometimes the vertical and horizontal stripes and even the nucleus of muscle cells are visible.
2.4 Connective tissue: it is colorless or yellowish bunches with unclear edges. After increasing 3% acetic acid, the collagen fibers are gelatinous and the elastic fibers are more clear. It is rarely seen in the feces of normal people, but more often in the feces of pepsin deficiency.
2.5 Plant cells and plant fibers: Plant cells have a variety of shapes, including round, oblong, and double-layered cell walls. There are many chlorophyll bodies in the cells. The plant fibers are spiral tube or grid-like structures, and the plant hairs are thin. A long, highly refractive tube with a pointed end. Such residues can be seen in normal feces, and increase in bowel movements and diarrhea. In severe cases, several plant fiber components can be observed with the naked eye.
3. Parasites and parasite eggs
The diagnosis of intestinal parasitic diseases mainly depends on microscopic examination to find eggs, protozoan trophozoites and their cysts. Common parasite eggs in the feces include roundworm eggs, hookworm eggs, whipworm eggs, pinworm eggs, Clonorchis sinensis eggs, Schistosoma sinensis eggs, gingerworm eggs, and tapeworm eggs. In order to improve the detection rate of eggs, various egg collection methods such as washing feces precipitation method or centrifugal precipitation method, and saturated brine flotation method are required. In addition, check the schistosome hair hoe can also use the miracidium hatching method. The significant protozoa in feces are mainly amoebic trophozoites and their cysts. Histolytic amoeba is the pathogenic amoeba; it can cause amoebic dysentery and other amoebic diseases, and colon amoeba It is a symbiotic amoeba without pathogenicity, so the distinction between two types of amoeba is very important in stool examination.
Giardia lamblia mainly parasitizes the duodenum and upper jejunum of humans, and can cause chronic diarrhea. If parasitic in the gallbladder can cause cholecystitis, its trophozoites can be found in the stool (only packages can be found in normal stools). bag). Giardia lamblia looks like a cut half of a pear shape. Two eye-like nuclei, a central axis and four flagella can be seen on its plane. The body rotates and is easy to identify. Cryptosporidium is a completely parasitic protozoa in the intestines. Since AIDS was reported in 1982, it has been confirmed as an important pathogen of AIDS patients and children with diarrhea. It has been listed as one of the important testing items for AIDS. The diagnosis of cryptosporidiosis mainly depends on stool The oocysts were found in.
Three, chemical inspections are required
1. Occult blood test (OB)
[Principle] Occult blood refers to a small amount of bleeding in the gastrointestinal tract, the appearance of the stool does not change, and the bleeding cannot be confirmed by the naked eye or microscope. Because hemoglobin has a similar peroxidase effect, it can catalyze the release of new ecological oxygen from hydrogen peroxide and oxidize chromogen substances to develop color.
[Methods and Results] Commonly used chemical methods include o-tolidine method, benzidine method, piramid hole method, colorless malachite green method, guaiac method, etc. The o-tolidine method has high sensitivity and can detect bleeding of 1～5ml in the digestive tract; the benzidine method, piramidon method, and the colorless malachite green method are moderately sensitive and can detect bleeding of 5～10ml; Guaiac The sensitivity of the method is poor, and it is positive when the bleeding reaches 20ml. The fecal occult blood test of normal people was negative.
[Clinical significance] Fecal occult blood test has important diagnostic value for gastrointestinal bleeding.
(1) Positive reaction: ①Peptic ulcer, the positive rate is 40% to 70%, which is intermittently positive; ②Malignant tumors of the digestive tract, such as gastric cancer and colon cancer, the positive rate can reach 95%, showing persistent positive, therefore, OB is often used as a diagnostic screening indicator for malignant tumors of the digestive tract; ③Others, such as acute gastric mucosal disease, intestinal tuberculosis, Crohn's disease, ulcerative colitis, hookworm disease, and epidemic hemorrhagic fever, are often positive for OB.
(2) False positive reactions: False positive reactions can occur when eating animal blood, meat, and eating a lot of vegetables, so a vegetarian diet is required for 3 days before OB. In recent years, some immunological examination methods have been established to solve the specific problem of OB and identify gastrointestinal bleeding. There are two kinds of antibodies used, one is anti-human hemoglobin antibody, the other is anti-human erythrocyte matrix antibody, the latter can be detected Bleeding from the lower gastrointestinal tract, the red blood cells or hemoglobin in the upper gastrointestinal bleeding has been degraded and denatured by digestive enzymes and has lost the original immunogen. The immunoassay occult blood test has high specificity and is not interfered by animal hemoglobin, so diet control is not required.
2. Bile pigment examination
2.1 Fecal bilirubin examination: there is no bilirubin in normal feces. After the normal intestinal flora has not been established in infants or adults, after a large amount of antibiotics are used in adults, or due to accelerated bowel movements such as diarrhea, bilirubin in the feces will not be bilirubin When the intestinal bacteria were restored, the stool was dark yellow and the bilirubin qualitative test was positive. If the bilirubin is partially oxidized to biliverdin, the stool will be yellow-green.
2.2 Examination of fecal bilogen and fecal biliary: Bilirubin is decomposed into urobilinogen (fecal bilogen) by bacteria in the terminal ileum and colon, and most of the bilirubin is in the colon except part of it is reabsorbed into the colon and hepatic circulation It is oxidized to urobilin (fecalbilin) when it stays and is excreted with feces. Due to the presence of fecalbilin, the stool is brown. When the biliary tract obstruction occurs, the fecal bilidin is reduced or absent, and the stool is light yellow or white clay-colored, and the high mercury chloride fecal bilidin test is negative. In hemolytic diseases, the fecal color darkens due to the increase in the content of fecal bilinin. Hepatocellular jaundice fecal bilidin can be reduced or increased, depending on the situation of intrahepatic obstruction. It is more helpful to diagnose if feces are kept for quantitative examination of feces; the content of feces in normal people is 75-350g per 100g of feces.
2.3 Bacteriological examination There are many bacteria in feces, accounting for 1/3 of the dry weight, and most of them belong to the normal flora. Escherichia coli, anaerobic bacteria and enterococci are the main bacterial groups in adult feces. Aerogenes, Proteus, and Pseudomonas aeruginosa are mostly passing bacteria, in addition to a small amount of Bacillus and yeast. None of the above-mentioned bacteria has clinical significance. Intestinal pathogenic bacteria inspection is mainly through direct fecal smear microscopy and bacterial culture. When pseudomembranous enteritis is suspected, Gram staining of stool smears shows that Gram-bacteria are reduced or disappeared, while Staphylococcus, Candida, or anaerobic Clostridium difficile is increased. Suspected of cholera or paracholera, take the fecal physiological saline drop to check, it can be seen that the fish shuttle-like active Vibrio. In some patients with diarrhea, a thin juice-like stool smear shows human yeasts, which resemble white blood cells or protozoan cysts. Distilled water can be used as a stool smear instead of normal saline. At this time, human yeasts are rapidly destroyed and disappeared, while white blood cells or protozoan cysts are not covered. damage. Suspected intestinal tuberculosis or pediatric pulmonary tuberculosis who cannot cough up sputum on their own can use stool acid-resistant staining smears to find mycobacteria. If stool culture (normal culture, anaerobic culture or tuberculosis culture) can be carried out, it will be more helpful for diagnosis and bacterial identification.