Congenital megacolon is a common disease in pediatric surgery and ranks second among congenital gastrointestinal anomalies. The basic pathological change is the lack of ganglion cells in the intermuscular and submucosal plexus of the intestinal wall, so congenital megacolon is also called “ganglion cell-free disease”. The proximal end of the spastic intestinal canal gradually expands and thickens due to long-term fecal accumulation, forming a megacolon. In fact, the main lesion of megacolon is in the spastic intestinal segment, and in about 90% of cases, the ganglion cell-free intestinal segment is located in the rectum and distal sigmoid colon, and in some cases, the whole colon, terminal ileum or only the end of the rectum is affected. 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 appear repeatedly. The absence of ganglion cells in the intestinal wall of congenital megacolon is a kind of intramural nerve development arrest, which prevents the ectodermal nerve fibers from participating in the normal intramural nerve plexus development. Neuroblasts begin to migrate cephalad to caudal along the vagal trunk at embryonic week 5 and reach the distal part of the GI tract at week 12. Neuroblasts are found in the wall of the esophagus at week 5, the stomach at week 6, the distal midgut at week 7, the middle transverse colon at week 8, and finally the entire wall of the GI tract to the rectum at week 12. However, the end of the rectum, the internal sphincter neuroblastoma, has not yet entered. During late embryonic development, the neuroblasts in the intestinal wall develop as neurons and gradually become ganglion cells. The absence of ganglion cells in the intestinal wall is caused when the neuroblastoma cell migration is stopped for various reasons. The earlier the pause, the longer the ganglion cell-free intestinal canal in the distal part of the colon. Since the rectum and sigmoid colon are at the most distal part of the GI tract, they are the most likely to be involved. Genetic factors for congenital megacolon were found to be familial, and since then reports of familial onset of congenital megacolon have gradually increased. With the in-depth study of genetics, it was recognized that congenital megacolon is a combined pathogenic effect of genetic and environmental factors and is a polygenic or multifactorial genetic disease, which is also called sex-modified multifactorial genetic disease. After molecular genetics was used to study the etiology of congenital megacolon, five mutated genes have been identified: RET gene, GDNF gene, EDN3 gene, EDNRB gene, and SOX10 gene. In addition to genetics and microenvironmental changes in the intestinal wall, there are definitely other factors involved in the etiology of congenital megacolon, and the genetics of congenital megacolon still needs to be studied in depth. Clinical manifestations 1. delayed fetal stool excretion, recurrent and persistent constipation and bloating: children have different clinical manifestations depending on the length of the diseased intestinal tube. The longer the spastic segment, the earlier and more serious the constipation symptoms appear. Most of them have no fetal stool or only a small amount of fetal stool within 48 hours after birth, and may develop symptoms of low-level partial or even complete intestinal obstruction, vomiting, abdominal distension, and no defecation within 2-3 days. If the spastic segment is not too long, a large amount of feces and gas can be excreted after rectal examination or warm saline enema and the symptoms are relieved, but the above symptoms will still appear intermittently afterwards, that is, constipation and abdominal distension will still occur after the symptoms of intestinal obstruction are relieved, and the enema must be dilated frequently in order to defecate, and in severe cases, it will develop into no enema and no defecation, and the abdominal distension will gradually increase. The spastic segment is long, the obstruction symptoms are not easy to relieve, and sometimes require emergency surgery. 2, malnutrition stunted development: long-term abdominal distension and constipation, can make the child’s appetite decreased, affecting the absorption of nutrients. Causes malnutrition, anemia, hypoproteinemia, etc. 3, megacolon with small bowel colitis: It is the most common and serious complication, especially in the neonatal period. Proximal colon secondary hypertrophy and dilatation, poor circulation of the intestinal wall is the basic cause, on the basis of this combined bacterial and viral infections, some children with abnormal immune function or allergic allergic reactions to the body and produced small intestinal colitis. The colon is the main site of involvement, with mucosal edema, ulceration, and limited necrosis, and inflammation invading the muscular layer may manifest plasma membrane congestion edema thickening intra-abdominal exudate, forming exudative peritonitis. The child’s generalized fever suddenly deteriorates, abdominal distension is serious, vomiting and sometimes diarrhea, due to diarrhea and a large amount of intestinal fluid accumulation in the enlarged intestinal canal, resulting in dehydration acidosis high fever, abdominal distension, blood pressure drop, if not treated in a timely manner, can cause a high mortality rate. Third, treatment 1, conservative treatment is adapted to the short segment type or ultra-short segment type, the lesion is relatively mild. The purpose is to achieve one bowel movement per day or every other day by various methods to relieve the symptoms of low bowel obstruction. However, because the symptoms in children with congenital megacolon are persistent, the use of a single method fails soon afterwards, and multiple methods are often needed alternately or in combination. Even then, it is sometimes difficult to maintain normal bowel movements. These include: (1) oral lubricants or laxatives: such as paraffin oil, phenolphthalein (fruit guide tablets), senna, rhubarb, etc.; (2) anal plugs: anal plugs with cork or glycerin suppositories, once a day or every other day; (3) enemas: 0.9% saline enemas are an effective treatment. Enema must pay attention to the amount of saline and discharge, such as saline infusion can not be discharged, need to inject glycerin, 50% magnesium sulfate solution, to be softened stool after re-enema, should pay attention to the occurrence of small intestinal inflammation, such as abdominal distension, fever, watery diarrhea and other symptoms should be promptly hospitalized. (4) Expansion of the rectoanal canal: the rectoanal canal is expanded once a day, metal expansion or stent expansion of the narrow section, half an hour each time. 2, surgical treatment (1) colostomy: foreign scholars mostly advocate fistula immediately after diagnosis, most hospitals in China in critical condition and high intestinal obstruction, the general condition of the child is poor, in order to save lives, do enterostomy. After the general condition improves, radical surgery will be performed. (2) Radical surgery for megacolon: Radical surgery is the fundamental method to treat congenital megacolon. Radical surgery requires adequate preoperative preparation, including good general nutritional status of the child and preparation of the colon (adequate bowel cleansing). There are many surgical methods, and the most common method used at home and abroad is transanal megacolon radical surgery (modified Soave procedure).