Abdominal pain is one of the most important symptoms of pediatric abdominal surgery and the main manifestation of acute abdominal disease. Because of the many causes and complex mechanisms of abdominal pain, in addition to common abdominal surgical diseases, many pediatric internal diseases of the digestive system, respiratory system, nervous system and urinary system can also be accompanied by abdominal pain. How to objectively and correctly analyze and identify abdominal pain, especially the characteristics of abdominal pain in acute abdominal diseases, is an important issue that pediatricians and many parents should pay attention to. 1, according to the time of occurrence of abdominal pain, abdominal pain can be divided into acute abdominal pain and chronic abdominal pain. In acute abdominal pain, the most important is the abdominal pain caused by acute abdominal disease, which can be divided into the following categories: (1) paroxysmal abdominal pain Paroxysmal abdominal pain is a typical symptom of acute mechanical intestinal obstruction, in order to overcome the resistance of the distal end of the intestine, the proximal intestine undergoes violent peristalsis, and the pain occurs at intervals consistent with the frequency of intestinal peristalsis, such as the paroxysmal abdominal pain that occurs in acute intestinal overlap. In addition to paroxysmal abdominal pain, complete intestinal obstruction is accompanied by cessation of defecation and exhaustion and abdominal distension. Hyperactive bowel sounds or air-over-water sounds can be heard during the onset of pain. In closed-loop intestinal obstruction, limited dilatation of the intestinal canal with significant pressure pain can be seen in the abdomen. When the intestinal lesion tends to be severe and blood flow obstruction occurs leading to strangulated intestinal obstruction, severe persistent abdominal pain with paroxysmal exacerbation may occur, and the condition may deteriorate rapidly, necessitating emergency surgical investigation. Intermittent colic is a symptom caused by strong spasmodic contraction of the smooth muscle of the duct wall after blockage of the abdominal cavity, such as biliary colic caused by biliary ascaris and colic occurring from ureteral calculi, which is unbearable pain, and abdominal examination often reveals fixed pressure points. In addition, the above-mentioned severe abdominal pain can occur in ovarian cysts with torsion and mesenteric vascular embolism. (2) Persistent abdominal pain Persistent abdominal pain indicates organ and peritoneal inflammation, which is mild at the beginning and gradually worsens later. When the lesion involves the plasma membrane and peritoneum, the pain site tends to be fixed. For example, acute appendicitis first manifests as persistent pain around the umbilicus, and as the inflammation of the appendix progresses, the pain is predominantly in the right lower abdomen, which clinically manifests as typical metastatic right lower abdominal pain. When appendiceal suppuration and perforation occur, it is manifested as persistent abdominal pain with peritonitis changes such as rebound pain and muscle tension. Gastrointestinal perforation from various causes can cause severe peritoneal inflammation, such as traumatic intestinal perforation, gastroduodenal ulcer perforation, etc. Characterized by rapid onset, severe abdominal pain, rapid spread of peritonitis to the whole abdomen, severe restriction or loss of abdominal breathing, whole abdominal pressure and muscle tension, “plate-like abdomen” and loss of bowel sounds in older children. There is often free gas and exudate in the abdominal cavity. Traumatic intra-abdominal organ rupture and bleeding are mostly caused by direct or indirect violence, especially the incidence of traffic accidents is increasing year by year, accounting for a large proportion of pediatric abdominal trauma cases, such as hepatic and splenic rupture and mesenteric vascular rupture and bleeding, clinical history of trauma and hemorrhagic shock manifestations, peritoneal irritation symptoms are obvious, puncture can extract non-coagulable fresh blood. (3) Acute abdominal pain caused by other medical diseases Abdominal pain caused by medical system disorders is usually not the first symptom, but often appears after fever and vomiting, and the pain is more moderate and the location is not fixed. For example, in acute gastroenteritis, due to accelerated intestinal peristalsis, it is manifested as vomiting and diarrhea, accompanied by paroxysmal abdominal pain, different from acute intestinal obstruction, with no fixed site of pressure pain, softness to palpation throughout the abdomen, no symptoms of irritation to palpation, active bowel sounds, and thin watery stools. In the case of mesenteric lymph node inflammation, there are signs of infection such as fever, followed by pain throughout the abdomen without fixed pressure points or inflammatory manifestations of the peritoneum, and ultrasound and other imaging examinations suggest enlarged abdominal lymph nodes. In chronic abdominal pain, it is mostly seen in older children and in chronic or subacute abdominal surgical diseases, such as chronic appendicitis, with frequently recurrent symptoms and deep in pressure pain in the right lower abdomen on examination. Others such as peptic ulcer, chronic incomplete intestinal obstruction, colon polyps, abdominal tumors, etc. can have a longer history of abdominal pain. 2.According to the cause of abdominal pain can be divided into visceral abdominal pain and induction abdominal pain. Visceral abdominal pain is innervated by the afferent fibers of sympathetic nerves, which is characterized by vague pain sensation, and it is not easy to describe the nature and location of pain accurately. According to the relationship between abdominal organs and innervation, upper abdominal pain may come from the stomach, duodenum, bile duct and liver; periumbilical pain comes from the small intestine, appendix, ureter, etc. For example, in acute appendicitis, although the appendix is located in the right lower abdomen, the pain is felt around the umbilicus; lower abdominal pain may be caused by lesions in the colon, rectum and pelvic organs. Induced pain is transmitted to the abdomen by the pain sensation of organ and tissue lesions adjacent to the abdomen. For example, pleurisy and lower lobe pneumonia can cause pain or discomfort in the upper abdomen. Pain from inflammation of the gallbladder and liver lesions can radiate to the scapular region; pain from ureteral stones can radiate to the ipsilateral groin region. 3, the concomitant symptoms of abdominal pain Abdominal pain as an important symptom of abdominal surgery, but not in isolation, often with the original disease appears different concomitant symptoms. The main symptoms associated with abdominal pain are: (1) nausea and vomiting The most common concomitant symptoms of abdominal pain are mechanical obstruction of the digestive tract, such as intestinal obstruction, which leads to reflux of digestive tract contents, and in patients with severe vomiting, gastrointestinal peristaltic waveforms can be seen on the abdominal wall. Ejective vomiting as occurs in hypertrophic pyloric stenosis. Some acute abdominal conditions, although not causing GI obstruction, can cause reflex vomiting due to stimulation of the gastrointestinal tract, such as vomiting in the early stages of acute appendicitis. The nature of the vomit contents can help determine the site and degree of GI obstruction. Non-bilious vomiting is mostly seen in obstruction above the duodenal jugular; turquoise bilious vomiting indicates that the obstruction is in the distal duodenum or proximal jejunum, such as poor intestinal rotation, which is typical of high intestinal obstruction; when the vomit contents are yellowish brown or fecal-like material, it indicates that the obstruction is low. (2) Defecation When abdominal pain occurs, pay attention to the defecation that accompanies abdominal pain. Paroxysmal abdominal pain with cessation of defecation and exhaustion suggests the presence of intestinal obstruction; if the paroxysmal abdominal pain is accompanied by jam-like bloody stools, it is a sign of acute intestinal loop; repeated abdominal pain with intermittent old bloody stools requires attention to the possibility of intestinal repetitive malformation and gastrointestinal polyps; abdominal pain and bloating with washboard watery stools are characteristics of acute necrotizing small bowel colitis. Anal finger diagnosis is an important examination tool. In summary, pediatric abdominal pain is both a very important symptom of abdominal surgical disease and a common manifestation of many organ lesions. Generally speaking, abdominal pain is the earliest or main symptom of acute abdominal disease, with rapid onset and gradual aggravation, and fever and vomiting appear after abdominal pain. There is obvious pressure pain on abdominal examination, and the location of the pain is often fixed; as the disease progresses, the pain increases and expands to the whole abdomen, with muscle tension and rebound pain. In children, because of the imperfect development of the omentum, the inflammation is weakly limited and the inflammation spreads rapidly, the course of the disease progresses more rapidly after the occurrence of acute abdomen, manifesting as persistent abdominal pain, pressure pain, rebound pain and myalgias throughout the abdomen, diminished or absent bowel sounds, and systemic symptoms of infection and toxicity. On the contrary, if the child first develops symptoms such as fever and vomiting, and then develops abdominal pain, the possibility of internal disease is greater. The abdominal pain caused by the latter is often mild or the abdominal pain site is not fixed, the abdomen is soft during examination, does not refuse to press, and there are no signs of peritonitis. Therefore, the time, nature, location and accompanying symptoms of abdominal pain should be carefully analyzed clinically, especially the accompanying gastrointestinal symptoms, such as vomiting, defecation and exhaustion, etc., in order to remove the falsehoods from the complicated clinical manifestations and clarify the cause.