Acquired megacolon in children most commonly due to
|B||Bad bowel habit|
|C||Chagas 's disease|
a. Chronically dilated, elongated, hypertrophied large bowel.
b. Megacolon may be congenital or acquired and is usually related to chronic mechanical or functional obstruction.
c. In general, the degree of megacolon is related to the duration of obstruction. Evaluation must always include examination of the colon and rectum (either endoscopically or radiographically) to exclude a surgically correctable mechanical obstruction.
a. Caused by Hirschsprung's disease results from the failure of migration of neural crest cells to the distal large intestine.
b. The resulting absence of ganglion cells in the distal colon results in a failure of relaxation and causes a functional obstruction.
c. The proximal, healthy bowel becomes progressively dilated. Surgical resection of the aganglionic segment is curative.
d. Although Hirschsprung's disease is primarily a disease of infants and children, it occasionally presents later in adulthood, especially if an extremely short segment of the bowel is affected (ultrashort-segment Hirschsprung's disease).
a. Result from infection or chronic constipation. Infection with the protozoan Trypanosoma cruzi(Chagas' disease) destroys ganglion cells and produces both megacolon and megaesophagus.
b. Chronic constipation from slow transit or secondary to medications (especially anticholinergic medications) or neurologic disorders (paraplegia, poliomyelitis, amyotrophic lateral sclerosis, multiple sclerosis) may produce progressive colonic dilatation.
c. Diverting ileostomy or subtotal colectomy with an ileorectal anastomosis is occasionally necessary in these patients