When it comes to upper gastrointestinal bleeding, some people are very frightened while others do not think so. Upper gastrointestinal bleeding is one of the common clinical emergencies with a morbidity and mortality rate of about 10%. Only an accurate understanding of what upper gastrointestinal bleeding is and its causes and how to diagnose and treat it can be treated correctly. There are two issues that must be clarified first: one is that vomiting blood is not necessarily upper gastrointestinal bleeding, and the other is that not vomiting blood is not necessarily the absence of upper gastrointestinal bleeding. The medical term for upper gastrointestinal bleeding refers to bleeding from the esophagus, stomach, duodenum, upper jejunum, and pancreatic duct or bile duct. Bleeding from these areas is easily diagnosed as upper gastrointestinal bleeding if it is large or rapid and is vomited through the mouth (but again, if the blood is vomited through the mouth, if it is coughed up through the lungs, it is called hemoptysis rather than upper gastrointestinal bleeding). However, even if the bleeding is from these areas, if the bleeding is slow and small, it usually does not occur as vomiting but as black stool or positive fecal occult blood test. In this case, it is easy to be overlooked because there is no blood vomiting, but it is also upper gastrointestinal bleeding. If the disease lasts long enough, it can still produce serious consequences such as anemia. There are many causes of upper gastrointestinal bleeding, most of which are due to lesions in the upper gastrointestinal tract itself, while a few are local manifestations of systemic diseases. According to domestic data, the four most common causes are ulcer disease (about 50%, especially duodenal bulb ulcer), rupture of esophageal and fundic varices due to liver cirrhosis (about 25%) and acute gastric mucosal damage (in the past, only 5% of upper gastrointestinal bleeding cases were diagnosed with acute gastric mucosal damage. Since the introduction of fiberoptic gastroscopy, the detection of acute gastric mucosal damage accounts for 15% to 30% of cases of upper gastrointestinal bleeding) and gastric cancer (patients are usually over 45 years old and often have loss of appetite and weight loss before bleeding, anemia is not proportional to the degree of bleeding, and epigastric pain does not decrease after bleeding, but sometimes increases. If a mass is palpated in the epigastrium and the lymph nodes around the left supraclavicular fossa and rectum are enlarged, then the gastric cancer is advanced). Other rare causes include esophageal hiatal hernia, esophagitis, pancreatic mucosal laceration, duodenal ballooning, gastric smooth muscle tumor, gastric mucosal prolapse, biliary tract or diverticular hemorrhage. One of the most common causes is bleeding from peptic ulcer disease. The main clinical manifestations of complicated upper gastrointestinal bleeding are vomiting blood and black stool, which may be accompanied by clinical manifestations of related conditions. The extent of the bleeding depends on the nature and location of the bleeding lesion, the amount and rate of blood loss, and also on the patient’s general condition at the time of bleeding. Blood vomiting from the esophagus is bright red, while blood vomiting from the stomach and duodenum is coffee-colored. Vomiting of bright red blood or blood clots indicates heavy bleeding, while if the bleeding is small and slow, it is coffee-colored. The typical black stool is a shiny, tarry paste, while in cases of massive bleeding, it is purplish red. Estimation of the amount of blood loss is extremely important for further management. Generally, if the daily bleeding volume is more than 5 ml, the stool color remains unchanged (but the blood test may be positive), and if the daily bleeding volume is more than 50-100 ml, black stools appear. If the blood loss is below 400 ml, there may be no conscious symptoms. When symptoms such as dizziness, panic, cold sweat, weakness and dry mouth appear, it means that the acute blood loss is above 400 ml; if there is fainting, cold limbs, little urination and irritability, it means that the blood loss is large, and the blood loss is at least 1200 ml; if the bleeding still continues, and there are symptoms such as shortness of breath and no urination in addition to fainting, the acute blood loss has reached If the bleeding continues, in addition to syncope and symptoms such as shortness of breath and anuria, the acute blood loss has reached more than 2000 ml. General diagnosis is mainly based on clinical manifestations and positive fecal occult blood test, changes in red blood cells, hemoglobin and platelets. At the same time, barium meal X-ray, fiberoptic gastroscopy, B-mode ultrasound and other examinations can be selected to further clarify the original cause of bleeding. The treatment of upper gastrointestinal bleeding should take into account both internal and external factors. In addition to general quiet rest and symptomatic medication, the effective circulating blood volume should be replenished in a timely manner. In case of moderate bleeding or above, blood transfusion may be required in appropriate amounts according to the condition, and appropriate hemostatic drugs should be used according to the cause and nature of bleeding. For bleeding caused by inflammatory disorders, H2 receptor antagonists can be used; for bleeding from ruptured esophageal varices, three-lumen tube compression can be used to stop bleeding. In recent years, there are still endoscopic hemostasis, esophageal variceal sclerotherapy injection hemostasis, microwave tissue coagulation hemostasis, thermal coagulation hemostasis and many other internal conservative therapies. However, if the conservative treatment is ineffective and active bleeding is not controlled, it is advisable to consider surgical treatment as early as the patient’s state allows in order to save life. Especially for recurrent upper gastrointestinal bleeding caused by portal hypertension in cirrhosis, surgery should be performed as early as possible due to the serious impact of blood loss on liver function, and one must not wait until the patient is dying before making a desperate attempt.