Black stool

Introduction Blood in the stool or black can be called black stool, blood after the stool or blood, blood can be mixed with or not mixed with feces, mainly depending on the level of bleeding, the amount of bleeding. Black stools indicate a higher bleeding site (far from the anus). No matter which kind of bleeding, it means that the blood vessels in the lesion have rupture. The light one is the nucleus, anal fissure or mucosal damage. The severe one may be polyps, inflammation, ulcer or tumor.

Cause

Some patients with ulcers have bleeding, and they are not aware of it. The reason is that when the bleeding is slow and the amount of bleeding is small, the naked eye can not see any change in the color of the stool, and the compensatory effect of the body makes the symptoms of blood loss not manifest. Only when the bleeding rate is faster and the amount of bleeding is more, the patient may find that his stool characteristics have changed, such as discharging tar-like black stools. When the amount of bleeding is larger and faster, dark red blood can be discharged, and even coffee and hematemesis can be vomited. It may also be accompanied by symptoms such as palpitations, dizziness, thirst, cold sweat, syncope, and shock.

About 10% of patients with ulcer disease and bleeding, usually do not have the symptoms common to ulcer disease, there is no obvious sign before bleeding, but the sudden major bleeding as the first symptom, hospitalization examination was diagnosed as ulcer disease combined with bleeding. Most other patients with symptomatic ulcers often induce bleeding due to excessive fatigue, improper diet, nervousness, climate change, and taking certain drugs (such as cold medicines and painkillers). The signs of bleeding are aggravation of upper abdominal pain, nausea, etc. The symptoms of pain after bleeding will be significantly reduced or even completely disappeared. The illusion of such symptoms is often misleading patients, neglecting timely medical treatment, resulting in delays in processing.

an examination

Related inspection

Fecal red blood cell feces volume fecal trait stool color regular

Black stools generally refer to stools that have a blackish-black appearance, a low fecal odor, a bloody smell, and an oily luster on the surface. Because they are similar in shape to asphalt (asphalt), they are also called tar-like stools. Black stools are usually caused by upper gastrointestinal bleeding. When red blood cells in the blood are decomposed in the intestine, hemoglobin iron combines with sulfides in the feces to form black iron sulfide under the action of bacteria such as gastric acid and intestinal E. coli, which makes the feces black; and iron sulfide stimulates the intestinal wall. The mucous membrane secretes a large amount of mucus, and the stool thus exhibits an oily luster like tar.

Differential diagnosis

Both black stools and bleeding can't be hooked. As mentioned above, when the amount of bleeding of the ulcer is small and the speed is slow, the appearance of the patient's stool does not necessarily change. Only by the fecal occult blood test can the potential bleeding not visible to the naked eye be detected. Therefore, it must not be said that the possibility of bleeding is denied if no black is seen.

On the contrary, when you see black stools, you can't think that there must be bleeding in the digestive tract. Because some foods or drugs can also make stool color black, because some foods or drugs themselves, or their metabolites, are black in color and have nothing to do with gastrointestinal bleeding.

For example, taking certain Chinese herbal medicines, activated carbon, ferrous carbonate, and some drugs for treating ulcer disease such as stomach must cure, bismuth subcarbonate, bismuth citrate, etc., the stool may be black, but the fecal occult blood test is negative, so it can Exclude bleeding; in addition, after eating too much pig liver, animal blood (such as pig blood, sheep blood, rabbit blood, etc.), the stool can also be dark red, even tar-like stool, and fecal occult blood test is also positive or strong Positive. If you have eaten pig liver and animal blood before the blackout, you can use the restricted diet (usually three days after the vegetarian diet) to change the occult blood test to negative, and the color of the stool is also normal to distinguish from upper gastrointestinal bleeding.

In the case of upper gastrointestinal bleeding and melena, although ulcer disease accounts for the majority, it cannot be considered as "there is no upper gastrointestinal bleeding without ulcer disease".

For example, cirrhosis with hemorrhage of the lower esophageal venous rupture, as well as the use of aspirin improper upper gastrointestinal bleeding can be quite serious. Therefore, do not limit the cause of upper gastrointestinal bleeding to ulcer disease. Of course, in patients with peptic ulcers such as gastric ulcers and duodenal ulcers, the use of aspirin has a greater possibility of causing bleeding, so it should be avoided as much as possible. If it must be used, it must be accompanied by an antacid and a gastric mucosal protective agent. .

For example, in the case of extensive burns, major surgery, high work stress, craniocerebral injury, severe infection, severe shock, respiratory failure, etc., the gastric mucosal blood vessels may undergo spasmodic contraction, causing ischemia. Necrosis; when the body is under stress, the release of hormones from the adrenal cortex increases, the secretion of gastric acid also increases significantly, and the gastric mucosa is prone to erosion, which is different from the ulcer disease that usually has symptoms such as upper abdominal pain, abdominal distension, acid reflux and belching. Stress ulcers. Patients with stress ulcers may have no history of ulcers, and may have no symptoms before bleeding, but the disease may have major bleeding or even shock.

To prevent stress ulcers, it is necessary to maintain personal emotional stability, pay attention to work and rest, and have a regular life. Although there is no history of ulcers, if there is continuous stressful work, as a preventive measure, you can also take stomach Shuping, sucralfate and other drugs that inhibit gastric acid secretion and protect the gastric mucosa; if you have a history of ulcers, you should be nervous. At the same time of work, oral cimetidine, ranitidine, Losec and other drugs to avoid emotional stress and induce bleeding.

Under normal circumstances, when the lower digestive tract is the lower part of the jejunum, ileum, colon, rectum and anus, the stool is dark red or fresh blood. Because the lower digestive tract is closer to the anus, the blood stays in the intestine for a shorter period of time, and it is too late for chemical reaction to be excreted. If the amount of lower gastrointestinal bleeding is small, the intestinal tract is not stimulated, the intestinal peristalsis is slow, and the blood stays in the intestine for a longer period of time. In this case, there is ample opportunity to complete the formation of the asphalt-like stool described above, discharging black stools.

Gastrointestinal hemorrhage causes changes in stool color, which is significantly related to the amount of bleeding. Some people have done experiments to introduce 5 ml of blood into the gastrointestinal tract of healthy people. The fecal occult blood test is positive, and the color of stool is not changed. One time, 50 to 70 ml of blood is introduced, the stool is black; one time, 500 to 1000 ml of blood is introduced. The color of the stool can be changed from black to red. It can be seen that the color of bloody stools is not only related to the location of bleeding, but also closely related to the amount of bleeding and the speed of bleeding.

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