There are many diseases causing abdominal pain, and the most common and representative ones are listed below: 1, acute gastroenteritis: abdominal pain is mainly in the upper abdomen and the umbilical region, often with continuous acute pain with paroxysmal intensification. It is often accompanied by nausea, vomiting, diarrhea, and also fever. Physical examination may find pressure pain in the upper abdomen or periumbilical area, mostly without muscle tension, more without rebound pain, and slightly hyperactive bowel sounds. It is not difficult to make a diagnosis when combined with the presence of unclean food and drink officials before the onset of the disease. 2, gastric and duodenal ulcers: it occurs in young and middle-aged people, abdominal pain is mainly in the middle and upper abdomen, mostly persistent trapped pain, mostly in the fasting episodes, eating or taking acidulants can be relieved as its characteristics. Physical examination may have middle and upper abdominal pressure pain, but there is no muscle tension and no rebound pain. Frequent attacks may be accompanied by a positive fecal blood test. Gastrointestinal barium meal examination or endoscopy can establish the diagnosis if there is a history of gastric or duodenal ulcer or similar symptoms, and then there is a sudden onset of severe pain in the middle and upper abdomen, like a knife cut, which rapidly extends to the whole abdomen. If the turbid zone shrinks or disappears, it suggests gastric or duodenal perforation. The diagnosis can be confirmed by abdominal X-ray confirming the presence of free gas under the diaphragm and inflammatory exudate from abdominal puncture. 3.Acute appendicitis: Most patients start with persistent vague pain in the middle abdomen, which shifts to the right lower abdomen after a few hours, with persistent vague pain with paroxysmal intensification. There are also a few patients who feel right lower abdominal pain at the beginning of the disease. The pain in the right lower abdomen is characterized by vague pain in the upper and middle abdomen after several hours. It may be accompanied by fever and malignancy. On examination, there may be pressure pain at the McDonald’s point and muscle tension, which are typical signs of appendicitis. The diagnosis of acute appendicitis can be clarified in combination with an increased total white blood cell count and neutrophils. If acute appendicitis is not diagnosed and treated in time, and the pain in the right lower abdomen is persistent after 1 to 2 days, with significant pressure pain, myalgias and rebound pain around the McDonald’s point, and significant increase in total leukocyte count and neutrophils, then gangrenous appendicitis may have become. If a mass with fuzzy edges is found in the right lower abdomen, an appendiceal mass has been formed. 4, cholecystitis, gallstones: this disease is more likely to occur in middle-aged and elderly women. In chronic cholecystitis, there is often vague pain in the right upper abdomen, which increases after eating fatty meals and radiates to the right shoulder. Acute cholecystitis often occurs after a fatty meal and presents with severe and persistent pain in the right upper abdomen, radiating to the right shoulder, mostly accompanied by fever and vomiting. Most people with cholelithiasis have chronic cholecystitis. Gallstones entering the cystic duct or moving in the bile duct can cause paroxysmal colic in the right upper abdomen, which also radiates to the back of the right shoulder. It is also often associated with malignancy. On physical examination, there is significant pressure and muscle tension in the right upper abdomen, and a positive Murphy’s sign is characteristic of cystitis. If jaundice is present, the bile duct is obstructed, and if the gallbladder is palpable, the obstruction is more complete. The total white blood cell count and neutrophils are significantly higher in acute cholecystitis. Ultrasonography and X-ray can confirm the diagnosis. 5. Acute pancreatitis: sudden onset after a full meal, persistent severe pain in the upper and middle abdomen, often accompanied by malignant vomiting and fever. Epigastric deep pressure pain, muscle renal tension and rebound pain is not very obvious. A significant increase in serum amylase may confirm the diagnosis of the disease. However, the increase in serum amylase often occurs 6 to 8 hours after the onset of the disease, so if the serum amylase is not high at the early stage of the disease, the possibility of the disease cannot be ruled out. If abdominal pain extends to the whole abdomen, and shock symptoms appear rapidly, and examination reveals full abdominal pressure pain with muscle tension and rebound pain, or even ascites and periumbilical and ventral skin spots, it suggests hemorrhagic necrotizing pancreatitis. In this case, the blood amylase may or may not be significantly increased. x-ray plain film shows that the stomach and small intestine are fully dilated while the colon is collapsed without gas. ct examination shows that the pancreas is enlarged and the surrounding fat layer disappears. 6, intestinal obstruction: intestinal obstruction can be seen in patients of all ages, children are more often caused by ascariasis, intestinal overlap, etc.. Adults are more often caused by hernia or intestinal adhesions, and the elderly can be caused by colon cancer and so on. The pain of intestinal obstruction is mostly around the umbilicus, with paroxysmal colic, accompanied by vomiting and cessation of defecation and exhaustion. During physical examination, intestinal pattern, abdominal pressure pain is obvious, intestinal sound is hyperactive, and even the sound of “gas over water” can be heard. If the abdominal pain is persistent with paroxysmal intensification, abdominal pressure pain is obvious with muscle tension and rebound pain, or more ascites, and rapidly present shock is suggested as strangulated intestinal obstruction. x-ray plain examination, if the intestinal cavity is found to be inflated, and there is most fluid usually the diagnosis of intestinal obstruction can be established. 7, abdominal organ rupture: the common ones are spleen rupture due to external force, liver cancer nodules due to external force or spontaneous rupture, spontaneous rupture of ectopic pregnancy, etc. The onset is sudden, with persistent severe pain involving the whole abdomen, often accompanied by shock. On examination, it is mostly found to be full abdominal pressure pain, which may have muscle tension and mostly rebound pain. Signs of accumulation of blood in the abdominal cavity can often be found. The rupture of abdominal organs can be confirmed by the presence of blood on abdominal puncture. Bleeding from ruptured ectopic pregnancy is often positive if the abdominal cavity is not punctured to the site of the posterior vault that can be punctured. Real-time ultrasonography, A-Tai protein assay, CT examination, and gynecological examination can help in the differential diagnosis of common organ rupture. 8, ureteral stones: abdominal pain often occurs suddenly, mostly in the left or right side of the abdomen with paroxysmal colic and radiating to the perineum. Abdominal pressure pain is not obvious. Painful episodes of hematuria can be seen as the characteristics of the disease, and the diagnosis can be made clearly by abdominal X-ray, intravenous pyelogram, etc. 9, acute myocardial infarction: seen in middle-aged and elderly people, the site of infarction such as in the diaphragm surface, especially the larger area has more epigastric pain. The pain mostly comes on suddenly after exertion, stress or a full meal, with persistent colic, and radiates to the left shoulder or the medial part of both arms. It is often accompanied by nausea and may be associated with shock. On physical examination, there may be mild pressure pain, no muscle tension and rebound pain in the upper abdomen, but the heart rhythm is often disturbed on auscultation. Electrocardiography can confirm the diagnosis of the disease. 10.Lead poisoning: It is seen in people who have been exposed to lead dust or fume for a long time, and occasionally it is also seen in people who have taken a lot of lead compounds by mistake. There are acute and chronic lead poisoning. But no matter acute or chronic, paroxysmal abdominal colic is its characteristic. The attacks are sudden and mostly around the umbilicus. It is often accompanied by abdominal distension, constipation and loss of appetite. On examination, abdominal signs are not obvious, there are no fixed pressure points, and bowel sounds are mostly diminished. In addition, lead lines can be seen on the edge of the gums, which is a characteristic sign of lead poisoning. Basophilic dot-colored red blood cells are seen in the peripheral blood, and the increase of blood lead and urine lead can establish the diagnosis.