Vomiting is a common symptom in newborns. The center of the vomiting reflex is in the fourth ventricle, adjacent to the vagus nerve and respiratory center, and is controlled and innervated by the cerebral cortex. When the abdominal organs and pharyngeal wall are stimulated, sensory impulses are transmitted to the center via the vagus nerve and visceral nerves and then reflected to the stomach, diaphragm, respiratory muscles, abdominal muscles, pharynx, palate, epiglottis and other related organs, causing a series of ataxic movements. Some infectious diseases can also cause vomiting due to central stimulation by toxins or increased intracranial pressure, where the center is stimulated by pressure and sends impulses through the vagus nerve, phrenic nerve, spinal cord and cranial nerves. Neonatal vomiting is divided into two main categories: organic vomiting (or surgical vomiting) and functional vomiting. Organic vomiting is mostly due to congenital malformations of the gastrointestinal tract and should be mostly acute and fatal and require immediate surgical treatment. 85% are medical and 18% are surgical. Clinical classification The clinical hallmark of organic vomiting is persistent and recurrent vomiting that interferes with milk intake and nutrition, and even dehydration. Depending on the vomit, it can be divided into the following five categories: 1. Continuous vomiting of large amounts of bile is the basic symptom of intestinal obstruction, indicating that bile cannot travel down. Obstruction below the second segment of duodenum, including cricothyroid pancreas, intestinal atresia or stenosis, and poor intestinal rotation. 2. Abdominal distension and vomiting bile is a typical symptom of low intestinal obstruction, indicating that bile is mixed with a large amount of intestinal fluid. Intestinal atresia, fetal stool intestinal obstruction, fetal fecal peritonitis. 3.Sudden vomiting of bile After birth and normal milk consumption, sudden and continuous vomiting of yellow water or bile indicates sudden intestinal obstruction. Commonly peritonitis caused by gastrointestinal perforation, intestinal obstruction caused by poor intestinal rotation and intestinal torsion, adhesional intestinal obstruction. 4, vomit is not yellow but a large number of milk flaps is obstruction above the duodenum. The most common is congenital hypertrophic pyloric stenosis. 5, choking saliva refers to the continuous choking after birth whether eating milk or not, indicating that swallowing immediately spit out. It is most often a pharyngeal malformation, more commonly esophageal atresia, and is the most urgent condition to treat. The first step is to distinguish functional vomiting from organic vomiting. In the former case, the vomit is fresh milk, which does not affect nutrition and daily weight gain; in the latter case, it is denatured milk or a large amount of digestive fluid. In the second step, organic vomiting is distinguished from direct or reflex vomiting in gastrointestinal lesions. The general rule is that simple obstructive vomiting does not affect the appetite, while reflex vomiting caused by disease always has other combined symptoms. In the third step, the height and nature of the obstruction are estimated by the color of the vomit and the form of vomiting to identify congenital complete intestinal obstruction or sudden intestinal obstruction. Finally, the various types of intestinal obstruction by embryologic pathology were then analyzed to the specific lesion. Additional emphasis is placed on brain birth injuries such as neonatal intracranial hemorrhage, subdural hematoma, neonatal asphyxia and cerebral edema causing vomiting, which occurs shortly after birth and is jet-like; often accompanied by symptoms such as shrill crying, cyanosis, convulsions, coma and pupil size asymmetry, which can be diagnosed when combined with a history of obstructed labor or asphyxia during labor. Diagnostic techniques of neonatal vomiting 1. Check medical history Understand vomiting, appetite, fetal stool, pregnancy and delivery history. 2. Physical examination Estimate the degree of dehydration, examine the abdomen, and check the rectum. 3.Insert gastric tube If vomiting is immediate after birth, insert gastric tube immediately. If the esophagus is atretic, pay attention to the gastric tube reflexion back to the mouth. If the tube is inserted smoothly into the stomach, the tube can be kept for observation. If there is difficulty in swallowing, gastric tube can be used for feeding, and if it is intestinal obstruction, gastric tube can be used for decompression. 4, blood and urine routine Too high for dehydration, too low to consider hemoperitoneum. More cells in urine is often due to dehydration. 5.Low-pressure quantitative barium enema. 6.Upper gastrointestinal tract angiography. 7.Transillumination test. 8.Other ultrasound, CT, MRI, etc.