Congenital megacolon is a common congenital intestinal malformation in children, also known as Hirschsprung’s disease. According to statistics, there is about 1 case per 5000 newborns, and the ratio of male to female is 4:1. Congenital megacolon has a genetic predisposition, and the basic pathological changes are the lack of ganglion cells in the intermuscular and submucosal plexus of the intestinal wall, and the increase in the number of unmyelinated parasympathetic nerve fibers. Because of the absence and reduction of ganglion cells, the diseased intestinal segment loses propulsive normal peristalsis and is often in spasm, forming functional intestinal obstruction and difficulty in passing feces. The proximal end of the spastic intestinal canal gradually expands and thickens due to the long-term accumulation of feces and forms megacolon. Therefore, in fact, the main lesion of megacolon is in the spastic intestinal segment, and about 90% of cases have ganglion cell-free intestinal segments located in the rectum and distal sigmoid colon, 12% of cases invade the M colon, 10% of cases have no ganglion cells in the whole large intestine, and only very few cases have lesions in both small and large intestine. In the neonatal period, the entire colon and even the small intestine are often extremely dilated due to intestinal spasm of the lesioned segment, and the symptoms of complete intestinal obstruction are repeatedly seen. Congenital megacolon manifests as follows: no fecal excretion or delayed fecal excretion after birth; persistent constipation, vomiting; anemia, emaciation; abdominal distension, highly distended abdomen, and coarse intestinal shape visible in the abdomen; rectal finger examination: a large amount of gas and loose stool is discharged with finger plucking. Small bowel colitis is the most common and serious complication, especially in the neonatal period. Its etiology is unclear and is related to poor circulation in the intestinal wall due to secondary hypertrophy and dilatation of the colon, abnormal immune function of the child, and infection. The colon is the main site of involvement, with mucosal edema, ulceration, and limited necrosis, and inflammation invading the muscular layer may show plasma membrane congestion and edema thickening with exudation in the abdominal cavity, forming exudative peritonitis. The child’s condition suddenly deteriorates with severe abdominal distension, vomiting, diarrhea, dehydration, acidosis, high fever, fine pulse, and decreased blood pressure, which can cause a high mortality rate if left untreated. In addition, malnutrition can also be complicated Clinically, if congenital megacolon is suspected, the following tests should be performed to clarify: 1. The typical spastic and dilated intestinal segments can be seen in the lateral and anterior-posterior pictures of barium enema, and the barium discharge function is poor, and the barium remains after 24 hours, and if the barium is not washed out by enema in time, barium stone can be formed, and the dilated intestinal wall is jagged when combined with enteritis, and the dilated intestinal tube can be seen only half a month after birth in neonates. If the diagnosis is still not confirmed, the following tests will be performed. 2, biopsy: take a small piece of tissue from the submucosa and muscle layer of the rectal wall more than 4 cm from the anus, and check the number of ganglion cells, and lack of ganglion cells in children with megacolon. 3.Anorectal manometry: Measurement of reflex pressure changes in the rectum and anal sphincter can diagnose congenital megacolon and differentiate it from other causes of constipation. false positive results can occur in newborns within 10 days. 4, rectal mucosal histochemical examination method: spastic segment submucosa and muscle layer ganglion cell deficiency at the hyperplasia, hypertrophy of parasympathetic preganglionic fibers constantly release a large amount of acetylcholine and cholinesterase, the number and activity of both can be determined by histochemical method than normal children out of 5 to 6 times, which can help the diagnosis of congenital megacolon and can be used for newborns. It is important to note that congenital megacolon in newborns should be differentiated from other causes of intestinal obstruction such as low small bowel atresia, colonic atresia, fetal constipation, and neonatal peritonitis. In older infants and children, it should be distinguished from secondary megacolon caused by recto-anal stenosis, tumor compression inside and outside the canal, colonic weakness (such as constipation caused by children with hypothyroidism), habitual constipation, and idiopathic megacolon in children (most of them have sudden onset after 2 years of age, due to dysfunction of the internal sphincter, which is mainly treated conservatively with comprehensive waive). In case of small bowel colitis, differentiate from viral or bacterial enteritis or septic bowel paralysis. For short-segment megacolon with mild constipation, comprehensive non-surgical therapy can be used, including regular isotonic saline lavage, anal dilation, glycerin suppositories, and laxatives to avoid fecal accumulation in the colon. If the above methods are ineffective, surgery should be performed even for short segments of megacolon. Where the spastic intestinal segment is long and constipation is severe, radical surgery must be performed. The most used surgeries are: 1, drag-out rectosigmoid resection (Swenson´s surgery); 2, colon resection rectum after colon drag-out (Duhamel´s surgery); 3, rectal mucosa peeling colon in the rectal muscle sheath Xian drag-out resection (Soave´s surgery). If the child has acute small intestinal colitis, nutritional development disorders, can not tolerate a radical surgery, should first improve the general condition, enterostomy, and later radical surgery.