Acute abdomen is a group of diseases characterized by acute onset of severe abdominal pain, which are generally critical and change rapidly, and timely and correct diagnosis can reduce complications and mortality. Physical examination, clinical manifestations and laboratory tests in acute abdominal disease are not specific. For a long time in the past, radiographs played an important role in the diagnosis of acute abdominal disease, so much so that clinicians relied on them to a large extent. However, X-ray plain films are somewhat limited in clarifying the etiology of acute abdominal disease because of the lack of natural contrast. And the prerequisite for further management in emergency medicine and surgery is a clear diagnosis. In recent years, with the advancement of the application of multi-layer spiral CT scanning technology, the imaging diagnosis of acute abdominal disease has been greatly improved. It has been proven that except for a few diseases causing acute abdomen, spiral CT has developed into the examination method of choice to determine the cause of patients with acute abdomen. The following is a brief description of multilayer spiral CT examinations for several common acute abdominal conditions. Appendicitis: X-ray plain films have limited diagnostic value for appendicitis, and about 50% of acute cases have no obvious X-ray findings, but abdominal plain films without positive findings do not exclude appendicitis. The special examination method of spiral CT is used to diagnose appendicitis, and its sensitivity and accuracy can reach 98% to 99%, especially for cases of appendicitis with atypical clinical symptoms and signs, and when the differential diagnosis is difficult, multilayer spiral CT can provide a valuable basis for differential diagnosis. Intestinal obstruction: Small and large bowel obstruction accounts for 20% of acute abdominal surgery. In the past, the diagnosis of intestinal obstruction was mainly based on clinical manifestations and X-ray plain film results, but there are still 20% to 30% of patients with unclear diagnosis, and further gastrointestinal imaging is required. The imaging examination is not only time-consuming, but also cannot fully reveal the site of obstruction and the cause of obstruction. In the diagnosis of intestinal obstruction, CT can reliably clarify the presence or absence of obstruction, the location, cause and degree of obstruction, whether it is simple or closed-collaterals obstruction, and whether there is strangulation or ischemia. The advantages of CT examination of intestinal obstruction cannot be overstated. Gastrointestinal perforation: Gastrointestinal perforation is a serious complication of peptic ulcer, diverticulitis, severe small bowel inflammation or infarction, trauma, tumor, or closed-collar intestinal obstruction. ct is ideal for evaluating peritonitis and can detect free gas in the abdominal cavity that is missed on chest or abdominal plain films. The most serious complications of small bowel ischemia are penetrating necrosis and perforation. ct is far superior to x-ray plain film in detecting dilated collaterals of small bowel ischemia with fluid accumulation, mucosal and intestinal wall thickening, and pneumatization of the intestinal wall and portal vein. Pancreatitis: CT plays an important role in the clinical management and evaluation of prognosis of acute pancreatitis.CT can detect intra-pancreatic hemorrhage or necrosis, as well as infiltration of inflammation into adjacent organs. It can indicate the prognosis of patients according to the degree of pancreatic necrosis. It has been shown that when the area of necrosis is greater than 50%, there is a 70% to 100% complication and 11% lethality. Magnetic resonance imaging can be helpful in the early diagnosis of acute pancreatitis when the CT sign is unclear. Ruptured aneurysm: Clinical manifestations of ruptured aneurysm include abdominal pain, pulsating mass and hypotension, but nearly 1/3 of patients do not have these typical clinical manifestations and are misdiagnosed with urinary stones or diverticulitis. Spiral CT may reveal periaortic hematomas, renal nudges, true and false lumens of aortic aneurysms, and appendicular thrombi that are difficult to visualize on radiographs. The abdominal hemorrhage: acute hemorrhage in the intestinal canal, mesentery, omentum, peritoneum or abdominal wall musculature can cause acute abdominal disease. x-ray plain film can only detect signs of peritoneal fluid and cannot identify simple ascites or hemorrhage. ct examination can detect high density hematoma and peritoneal blood accumulation according to the CT value of the lesion. In addition, CT is significantly better than X-ray plain film for patients with diverticulitis, intra-abdominal purulent infection, cholecystitis, and bile duct stones. Problems in the selection of imaging methods for acute abdominal examinations: At present, in the application list for acute abdominal examinations, X-ray plain films are significantly more than CT examinations, and the reasons for this are mainly the following: (1) unfamiliarity with new technologies in imaging: many clinicians have limited knowledge of imaging, or aging knowledge and old-fashioned concepts, or are limited to previous experience, and do not understand the application of new technologies such as CT in the clinical value. (2) Inability to effectively communicate with imaging departments and stereotypical thinking: some patients do not have a clear diagnosis despite multiple abdominal X-ray plain films, and they do not take the initiative to communicate with imaging departments and discuss the examination plan, resulting in delaying the disease and leading to adverse consequences. (3) Thinking that CT examination is expensive: In fact, this is a misunderstanding. At present, the cost difference between plain abdominal X-ray examination and spiral CT examination is not significant, and spiral CT examination provides more and more valuable information, improves the diagnostic certainty and differential diagnosis of acute abdominal disease, the accuracy degree and reliability of surgery provides a guarantee, and to a large extent, can avoid misdiagnosis and misdiagnosis and blind surgical exploration.