Hirschsprung’s disease (HD) is caused by congenital ganglion cell deficiency and involves the distal rectum and different lengths of the intestine. In about 75% of patients, the lesion involves the rectum and part of the sigmoid colon, but it can also involve more proximal segments of the intestine, the entire colon, and in rare cases, most of the small intestine. The vast majority of patients with megacolon (HD) are diagnosed in the neonatal period, when they present with symptoms of distal bowel obstruction, including bilious vomiting, abdominal distention, and inability to defecate. HD should be highly suspected in infants with predisposing factors (e.g., Down syndrome), or in infants with a family history of HD. patients with less severe HD may not be diagnosed until later infancy or childhood. These patients usually have a history of chronic constipation and growth retardation. Rarely, affected infants may develop small bowel colitis, a potentially life-threatening condition in which patients present with septic-like features of fever, vomiting, diarrhea, and abdominal distention that can progress to toxic megacolon (megacolon crisis) A definitive but invasive diagnosis of megacolon (HD) can be made by rectal biopsy. Results of abdominal radiography, barium enema, or anorectal manometry (ARM) may support the diagnosis. In the case of megacolonization small bowel colitis (HAEC, requiring urgent management) The treatment of megacolonization (HD): is surgical removal of the segment of bowel without ganglion cells. The segment with normal ganglia is pulled down to anastomosis with the anus, and sphincter function is usually preserved. Most patients with megacolon (HD) have normal or near-normal levels of anorectal function after radical surgery, and most enjoy an excellent quality of life, although certain abnormalities of bowel function are common. The most common complications: fecal incontinence and constipation. Postoperative small bowel colitis may also occur, which is a medical emergency! The causes are complex and the risks are great.