I. What is congenital megacolon? Congenital megacolon (Hirschsprung′s discase) is also known as agangliono-sis (absence of ganglion cells in the intestinal canal). Since hirschsprung describes it in detail, it is usually called Hirschsprung’s- Disease, which is a common congenital intestinal malformation in children due to persistent spasm of the intestinal canal in the distal rectum or colon and stagnation of feces in the proximal colon, making this intestine hypertrophic and dilated.
Do you know about congenital megacolon?
The disease is characterized by the absence of intermuscular nerve cells in the distal part of the affected intestinal segment, which causes spasmodic contraction and narrowing of the intestinal tube and loss of peristaltic capacity. The proximal intestinal segment is dilated, with secondary compensatory dilated hypertrophy. The incidence is 1 case in 2000-5000 newborns, which is second only to rectoanal malformation and ranks the second in gastrointestinal malformation in newborns. According to the data from Shanghai (1966-1975), the incidence of GI malformations accounted for 24.67% of congenital malformations. And this disease occupies the 4th place of GI malformations. According to Passarge et al. 414 cases were reported, with a male to female ratio of 5-10:1. There is a clear tendency of family morbidity, and the data suggest that the disease may be polygenic. In the past 20 years, due to the progress of histology, histochemistry, electron microscopy, immunohistochemistry and other research methods. In the past 20 years, due to the progress of histology, histochemistry, electron microscopy, immunohistochemistry and other research methods, people have made great progress in congenital megacolon pathology, physiological histology, embryonic development, genetic diagnosis and treatment.
Clinical manifestations of congenital megacolon
1.Constipation
Most of the cases have delayed fetal stool excretion after birth and persistent constipation and abdominal distension. Children have different clinical manifestations depending on the length of the lesioned intestinal canal. There is no fetal stool discharge or only a small amount of fetal stool discharge within 24 to 48 hours after birth, and symptoms of low-level partial or even complete intestinal obstruction may appear within 2 to 3 days, with vomiting and abdominal distention without defecation. The longer the spastic segment, the earlier and more severe the symptoms of constipation appear. If the spastic segment is not too long, a large amount of meconium and gas can be excreted after rectal examination or warm saline enema and the symptoms are relieved. If the spastic segment is not too long, the obstructive symptoms are not easily relieved, and sometimes emergency surgery is needed. After the symptoms of intestinal obstruction are relieved, there is still constipation and abdominal distension, and it is necessary to frequently dilate the anus and enema to defecate, and in serious cases, it develops into no enema and no defecation, and the abdominal distension gradually increases.
2.Vomiting
Vomiting is a common symptom of neonatal megacolon, generally less often, but there are also frequent vomiting, vomit can have bile in the vomit, and occasionally vomit stool-like material.
3.Abdominal distension
Most children have abdominal distension, due to the high degree of abdominal distension, the umbilicus protrudes outward, the skin of the abdominal wall is shiny, the veins are angry, and even compression of the diaphragm causes breathing difficulties. The accumulation of feces makes the colon hypertrophic and dilated, and huge intestinal patterns and peristaltic waves are sometimes seen in the abdomen. In children, feces-filled intestinal collaterals and fecal stones can be palpated in the left lower abdomen.
4.Malnutrition and growth retardation
Due to long-term constipation, poor appetite and impaired absorption of nutrients, the growth and development of the affected children are significantly behind normal children of the same age, and the older they are, the more significant they are.
Diagnosis of congenital megacolon
1. Medical history and physical signs
More than 90% of children do not have fetal stool within 36-48 hours after birth, and later have a history of obstinate constipation and abdominal distention, and must pass through enemas, take laxatives or plug anal plugs to defecate. There is often malnutrition, anemia and loss of appetite. The abdomen is highly distended and visible in a wide intestinal pattern, and rectal palpation feels that the rectal jug abdomen is empty and cannot palpate feces, beyond the spastic segment to the dilated segment where stool is palpated. (Clinically encountered is a newborn baby with discomfort inflammation caused by abdominal distension, vomiting, stool does not resolve. In older children, the stool must be unblocked or stimulated, or once every 4-7 days).
2.X-ray view
The standing abdominal plain film mostly shows low level colonic obstruction. In the lateral and anterior-posterior pictures of barium enema, the typical spastic intestinal segment and dilated intestinal segment can be seen, and the barium discharge function is poor, and the barium remains after 24 hours. If the diagnosis is still not confirmed, the following tests will be performed.
3.Biopsy
Take a small piece of tissue from the submucosa and muscle layer of the rectal wall more than 4cm from the anus to check the number of ganglion cells, and lack of ganglion cells in children with megacolon. (It is clear that it is really necessary, but children who are too young usually do not do it)
4.Anal rectal manometry
Measurement of reflex pressure changes in the rectum and anal sphincter allows diagnosis of congenital megacolon and identification of other causes of constipation. In normal children and functional constipation, when the rectum is stimulated by distension, the internal sphincter immediately undergoes reflexive relaxation and the pressure decreases, while in children with congenital megacolon the internal sphincter does not relax, but also undergoes significant contraction, which increases the pressure. This method can sometimes show false positive results in newborns within 10 days.
5, rectal mucosal histochemical examination method
According to the spastic segment submucosa and muscle 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 chemical methods are 5 to 6 times higher than normal children, which helps in the diagnosis of congenital megacolon and can be used in neonates.
V. How to treat congenital megacolon?
The treatment of congenital megacolon includes conservative treatment and surgical treatment. Once diagnosed, radical megacolon surgery is required sooner or later to relieve symptoms. Conservative treatment is suitable for children with mild clinical manifestations, young age, incomplete diagnosis and preparation for surgery, etc. The main methods are: stimulating the anorectum with soap paste, corkage, etc., and using warm saline enema to cause defecation if necessary. Surgical treatment includes transitional surgery (enterostomy) and definitive surgery. Enterostomy is generally used for patients with complicated small bowel colitis, intestinal perforation or poor general nutritional status that cannot tolerate major surgery, and radical surgery will be performed after the general condition has improved. Radical surgery involves complete removal of the stenotic intestinal segment at the lesion and restoration of intestinal continuity. Due to improved surgical techniques and monitoring, children with congenital megacolon at 6 months of age or even earlier can safely undergo radical surgery, thus avoiding complications such as small bowel colitis and malnutrition. In addition, children should be trained to defecate after surgery and have their anus dilated regularly under the guidance of doctors to consolidate the long-term results.
Prognosis
The prognosis of natural regression of this disease is poor, and most of them die due to malnutrition or colonic crisis. According to many sources, the mortality rate within 6 months is 50% to 70%. Most neonatal deaths are due to complications of enterocolitis. Untreated survival to adulthood is rare; even if they survive to adulthood, there is still a risk of death from colonic crisis at any time. The survival rate of patients with megacolon has improved significantly in recent years, and deaths are rare in patients with delayed diagnosis of complicated small bowel colitis and sepsis and in patients with total colonic anaplasia with apparently widespread proximal small bowel, and many deaths are due to associated Down syndrome. Children who develop small bowel colitis prior to surgery are likely to continue to have this complication after colostomy and tow-out, with an overall patient survival rate of over 90%. Long-term follow-up is important, as most patients (>96%) have controlled stools after surgery, with fecal soiling in 2-3% and fecal incontinence rare (<1%). Constipation may occur in some patients (10%-20%), but can often be improved with a high-fiber diet and stool softeners, and the symptoms associated with most patients after surgery can gradually improve with age.