Infants and children with acute necrotizing enterocolitis have atypical symptoms, with the onset of the disease in the first 3 to 10 days of life. They are admitted to the intensive care unit due to prematurity or low birth weight. During artificial feeding or during nasal feeding with a gastric tube placed in immature children due to incomplete establishment of the swallowing reflex, they are found to have retention in the stomach, followed by abdominal distention, vomiting, fever with blood in the stool or temperature not rising, tachycardia or slow heart rate, abdominal muscle tension, abdominal distension, erythema of the abdominal wall, and other signs. What are the examination methods of acute necrotizing enterocolitis? 1, routine blood tests Total white blood cells and neutrophils are increased, and there is a left shift of the nucleus, toxic particles and vacuoles; platelets are mostly reduced, more obvious in severe cases. 2, routine stool examination can be seen a large number of red blood cells, a small number of white blood cells, a strong positive occult blood test, gram staining can be seen more gram-positive short and thick bacilli, sometimes can see the necrosis of the intestinal mucosa and pseudomembrane. 3.Fecal culture Most of them can be isolated from the gas-producing bacilli, but also pathogenic Escherichia coli, Bacillus dysenteriae, Salmonella, etc. 4.Coagulation mechanism examination Coagulation time is often prolonged, prolonged prothrombin time, plasma fisetin paraclotting test is mostly positive, coagulation factors have different degrees of reduction. 5.Electrolyte test Low blood sodium, low blood potassium, low chlorine and acidosis, etc. 6.B ultrasound examination The accumulation of experience in imaging examination of gastrointestinal tract, there is a tendency to complement each other with X-ray examination. 7, X-ray examination Acute necrotizing enterocolitis has a variety of X-ray manifestations, different clinical types of different stages of the disease due to different pathological changes in its X-ray manifestations are also different, the abdomen supine orthopantomography and standing X-ray plain film is the main method to confirm the diagnosis of the disease, because of the risk of intestinal perforation, it is prohibited to do barium meal and barium enema examination, the acute phase of the film every 6 hours to observe the changes in the condition, early to small intestine flatulence is dominant, the intestinal wall between the widening is The early stage is mainly small intestinal flatulence, the widening of the intestinal wall is due to intestinal mucosa and submucosa edema, congestion, necrosis, cystic gas accumulation in the intestinal wall, increased fluid in the intestinal lumen, widening of the intestinal gap (if the widening of the intestinal gap is more than 5cm, it has diagnostic significance), thickening or blurring of the intestinal mucosal folds, and even deep serrated changes in the edges, some patients have large span arch or ladder arrangement of the intestinal canal, in severe cases, large pieces or segmental necrosis or perforation of the intestinal canal, X-ray manifestations are power intestinal obstruction, intestinal paralysis, local intestinal stenosis, rigidity, loss of normal soft arc, pneumoperitoneum plane is obvious, increased or progressive increase of intra-abdominal exudate, gathering of intestinal curves to the center of the abdomen, widening and blurring of the distance between the intestinal tube and the abdominal wall, increased density of the whole abdomen, if the whole layer of an intestinal segment is necrotic, intestinal loops are seen to be dilated, power is lost, position and morphology are fixed, suggesting serious lesions, imminent perforation or perforated, pneumoperitoneum The pneumoperitoneum is an X-ray feature of intestinal perforation, with free gas in an inverted triangular translucent shadow between the anterior abdominal wall and the inflatable intestine.