1, digestive tract diseases: The most common causes of hematochezia include esophageal varices, esophageal foreign bodies, ulcers, acute gastritis, gastric mucosal prolapse, intussusception, hemorrhagic necrotizing enteritis, strangulated intestinal obstruction, Meckel's diverticulum, intestinal polyps, anal fissure, etc.
2, blood diseases: neonatal bleeding, hemophilia, leukemia, aplastic anemia, thrombocytopenia and allergic purpura.
3. Other systemic infectious diseases: septicemia and typhoid fever. Neonates swallow blood from the mother's birth canal or nipple rupture, and swallow bleeding from the nose, pharynx and gums.
4, the influence of food or drugs: Some foods and drugs can also cause changes in stool color, sometimes easily confused with blood in the stool. For example, eating watermelon and tomatoes in large quantities in summer can turn the stool color red, anemia children can turn black after iron supplementation, and the stool color can also turn black after eating animal blood, liver and meat or iron and carbon supplementation.
Note: Black stool cannot be absolutely linked to bleeding!
Readers who insist on whether there is black stool to decide whether there is bleeding are too absolute. Black stool generally refers to the appearance of black paste in stool, with less fecal odor, bloody smell and oily surface. Because it is similar to asphalt (asphalt), it is also called asphalt stool. Black stool is generally caused by upper gastrointestinal bleeding. When the red blood cells in the blood decompose in the intestine, hemoglobin iron combines with sulfide in the feces under the action of bacteria such as gastric acid and intestinal Escherichia coli to form black iron sulfide, which makes the feces black; Moreover, iron sulfide stimulates the intestinal wall, so that the mucosa secretes a lot of mucus, so the stool presents an oily luster like tar.
However, black stool and bleeding cannot be absolutely linked. As mentioned above, when the bleeding volume of ulcer is small and slow, the appearance of stool of patients may not necessarily change. Only through the examination of fecal occult blood can we find the potential bleeding that can't be observed by the naked eye. Therefore, in the absence of black stool, we must not deny the possibility of bleeding.
On the contrary, when you see black stool, you can't assume that there must be bleeding in the digestive tract. Because some foods or drugs can also make the stool black, this is because some foods or drugs themselves, or their metabolites are black and have nothing to do with gastrointestinal bleeding.
For example, taking some Chinese herbal medicines, activated carbon, ferrous carbonate, and some drugs for treating ulcers, such as Weibizhi, bismuth carbonate, bismuth citrate, etc. The stool may be black, but the fecal occult blood test is negative, so bleeding can be ruled out; In addition, after eating too much pig liver and animal blood (such as pig blood, sheep blood, rabbit blood, etc.). ), stool can also be dark red, or even tarry stool, stool occult blood test positive or strong positive. If you eat pig liver or animal blood before discharging black stool, you can distinguish it from upper gastrointestinal bleeding by limiting your diet (usually vegetarian for three days), then the occult blood test turns negative and the stool color returns to normal.
Upper gastrointestinal bleeding is not a patent of ulcer disease.
In the cases of upper gastrointestinal bleeding and melena, although ulcer disease accounts for the majority, it cannot be thought as some readers do that "upper gastrointestinal bleeding will not occur without ulcer disease".
For example, liver cirrhosis complicated with bleeding of lower esophageal vein, and improper use of aspirin leads to upper gastrointestinal bleeding, which may be quite serious. Therefore, don't limit the cause of upper gastrointestinal bleeding to ulcer disease. Of course, in patients with peptic ulcer such as gastric ulcer and duodenal ulcer, aspirin is more likely to cause bleeding and should be avoided as much as possible. If you must use it, you must take it with antacid and gastric mucosal protective agent at the same time.
For example, under stress conditions such as extensive burns, major surgery, high work pressure, craniocerebral injury, serious infection, severe shock, respiratory failure, etc. The gastric mucosal blood vessels may contract spasmodically, thus causing ischemia and necrosis; When the body is in a state of stress, the release of adrenocortical hormone increases, the secretion of gastric acid also increases obviously, and the gastric mucosa is prone to erosion, forming a stress ulcer different from the ulcer disease that usually has symptoms such as upper abdominal pain, bloating, acid regurgitation and belching. Patients with stress ulcer may have no history of ulcer and no symptoms before bleeding, but the disease may cause massive bleeding and even shock.
To prevent stress ulcer, it is necessary to maintain personal emotional stability, pay attention to the combination of work and rest, and live a regular life. Although there is no history of ulcer, if you have continuous intense work, as a preventive measure, you can also take drugs such as metoclopramide and sucralfate to inhibit gastric acid secretion and protect gastric mucosa. If you have a history of ulcer, you should take cimetidine, ranitidine, losec and other drugs orally while doing stressful work to avoid bleeding due to emotional tension.
Lower gastrointestinal bleeding can also lead to melena.
Under normal circumstances, when the lower digestive tract is bleeding from jejunum, ileum, colon, rectum and lower anus, the stool is dark red or bloody. Because the lower digestive tract is close to the anus, the blood stays in the intestine for a short time, and it has been discharged from the body before a chemical reaction takes place. If the amount of bleeding in the lower digestive tract is small, it will not stimulate the intestine, and the intestine will move slowly, so the blood will stay in the intestine for a long time. In this case, there is enough opportunity to complete the formation process of tar-like stool mentioned above and discharge black stool.
Gastrointestinal bleeding causes the color change of stool, which is obviously related to the amount of bleeding. Someone has done experiments to introduce 5 ml of blood into the gastrointestinal tract of healthy people, and the stool occult blood test is positive, but the stool color has not changed; Draw 50 ~ 70 ml of blood at a time, and the stool is black; When 500 ~ 1000 ml of blood is infused at a time, the color of stool can change from black to red. It can be seen that the color of blood in stool is not only related to the bleeding site, but also closely related to the amount and speed of bleeding.
[Edit this paragraph] Prevention and treatment
Ulcer is characterized by a long course of disease, periodic remission, repeated exacerbation of symptoms in recurrent attacks, and obvious seasonality. At the turn of autumn, winter and spring, common symptoms, emotional fluctuation or work stress, improper diet, excessive alcohol and tobacco, drug stimulation, etc. can aggravate the symptoms and induce bleeding. Knowing these characteristics of ulcers, how to prevent them?
First of all, we should have a regular daily life and pay attention to the combination of work and rest, especially in winter to keep warm and avoid catching a cold. In terms of diet, it is not advisable to eat more or less. Generally, it is not good for patients with peptic ulcer to eat less and eat more meals. Do not eat hard, sour, sweet and spicy food for three meals a day. Strong tea, coffee and cold, overheated and gassy food are not suitable for drinking. Smoking will affect the curative effect of ulcer, reduce the healing rate of ulcer, and drinking will weaken the protective factors of gastric mucosa and stimulate the increase of gastric acid secretion. The above factors should be avoided as far as possible.
In addition, Helicobacter pylori is an important pathogenic factor and recurrence factor of ulcer disease, which should be eradicated.
When there is black stool or hematemesis, patients and their families should keep calm. If it is only black stool, you should go to the hospital as soon as possible accompanied by your family, do gastroscopy as soon as possible, make clear the cause of bleeding, and treat it in time. If you have vomiting blood, dizziness, palpitation, cold sweat and general weakness, you should temporarily fast, stay in bed immediately, and keep your head low and your feet high to ensure blood supply to your brain. The patient's head should also be tilted to one side, so as to avoid choking when vomit is inhaled into the trachea. At the same time, call "120" as soon as possible and ask the medical staff to come for treatment.