Hirschsprungs Disease (Congenital Megacolon):
This is also known as congenital megacolon. There is absence of ganglion cells, submucus plexus and intramural plexus (parasympathetic ganglion cells) in distal segment usually rectosegmoid junction. Incidence is one in 5000 live birth.
It is more common in males than in females.
In Hirschsprungs Diseasefthere is an arrest in embroylogic development affecting the migratioon of parasympathetic nerves (innervation) of the intestine occuring before 12 weeks of gestation due to genetic cause. This leads to the functional obstruction of the colon due to lack of peristalsis in this area leading to the accumulation of feces and gas proximal to the area of defected part. Due to accumulation of feces the colon becomes distended so the condition is called as megacolon.
Neonate will present with failure to pass meconium and abdominal distention within a day or two after birth and if rectal examination is done by little finger there will be an explosive leakages of accumulated meconium and gas. There may be weight loss and dehydration due to bile-stained vomiting as a result of obstruction and failure to take fluid. Neonate may develop shock. Older childern will present with obstinate constipation with abdominal distention undernutrition and anorexia. There may be diarrhoea alternating with constipation due to bacterial action which liquefies the stool. The fecal mass can be palpated in left lower portion of abdomen and rectal examination shows empty rectum. Diagnosis is supported by barium enema which shows constricted portion of aganglionic bowel distal to the dilated part of colon and diagnosis is confirmed by rectal biopsy which shows absent ganglion cells in submucosa and intermusular plexus with or without increased number of nerve fibres.