According to the following conditions can be excluded: 1, the presence of constipation: normal infants have stool every day, and the color, shape and volume of stool are normal, from the clinical manifestations to exclude megacolon; 2, distinguish habitual constipation and megacolon constipation: megacolon is a congenital disease, through prenatal screening can be found in the fetal intestinal tube dilatation, after birth fetal stool delay, 1-3 months after birth have constipation Constipation is often accompanied by abdominal distension. Children with habitual constipation have normal bowel movements before the age of three, but after the age of three, constipation occurs for some reason, and the symptoms become more and more severe, resulting in abnormal bowel habits; 3. Barium enema examination of the anus and rectum is used to identify whether congenital megacolon.