megacolon
| Noun | 1. | megacolon - an abnormal enlargement of the colon; can be congenital (as in Hirschsprung's disease) or acquired (as when children refuse to defecate) |
Megacolon
megacolon
[′meg·ə‚kō·lən]Megacolon
in man, enlargement of part or all of the colon.
Megacolon usually originates with congenital immaturity of the colon’s innervation apparatus. The clinical course of the condition is characterized by persistent constipation beginning in the first years (sometimes in the first months) of life. This, the most common form of megacolon, is called Hirschsprung’s disease. In adults, megacolon may be caused by the presence of mechanical obstructions (tumor, cicatricial stenosis). Treatment is surgical.
megacolon
megacolon
[meg″ah-ko´lon]
meg·a·co·lon
(meg'ă-kō'lon),megacolon
(mĕg′ə-kō′lən)megacolon
A massively distended colon with decreased peristaltic activity, due to defective innervation (congenital), intraluminal overgrowth of microorganisms or of psychogenic origin.Clinical findings
Intestinal obstruction, constipation, vomiting, abdominal distension, poor weight gain, retarded growth.
Management
Temporary colostomy for bowel rest, followed by resection of affected bowel segment.
Prognosis
Symptoms eliminated in ± 90% of patients with surgery; outcomes better with early intervention.
Megacolon—Congenital and Acquired
Congenital (Congenital aganglionosis, Hirschsprung’s disease)
A disease affecting 1:5000 live births, with a sibling risk of 1% for girls and 5% for boys; Hirschsprung’s disease (HD) is ten-fold more common in Down syndrome; other anomalies in HD include hydrocephalus, VSD, cryptorchism, diverticulosis of the urinary bladder, renal cysts and agenesis, polyposis coli and Laurence-Moon-Biedl syndrome.
Pathology
In affected regions the colon is narrowed and the intramural ganglion cells are absent in both the submucosal (Meissner’s) and myenteric (Auerbach’s plexi).
Molecular genetics
Megacolon is associated with mutations in the RET gene.
Management
Resection of aganglionic colon.
Acquired
A condition related to narcotics or disruption of ganglionic innervation (e.g., idiopathic hypomotility, neuropathies (parkinsonism), multiple sclerosis, myotonic dystrophy, diabetic neuropathy, Chagas’ disease, smooth muscle disorders (amyloidosis and progressive systemic sclerosis) and metabolic disease (hypokalemia)), lead poisoning, porphyria, pheochromocytoma, hypothyroidism. It may be due to intraluminal overgrowth of microorganisms in Crohn’s disease and ulcerative colitis (toxic megacolon), characterised by mucosal necrosis, transmural inflammation and systemic toxicity with high fever, tachycardia, leukocytosis and diarrhoea.
In psychogenic megacolon, no radiologic or pathologic defects are present; it may be related to a “fixation” in Freud’s anal retentive stage of psychosexual development, with constipation of later onset than in HD, possibly 2º to abuse of anthracine laxatives.
megacolon
A massively distended colon with ↓ activity, due to defective innervation–congenital, intraluminal overgrowth of microorganisms or of psychogenic origin Clinical Intestinal obstruction, constipation, vomiting, abdominal distension, poor weight gain, retarded growth Management Temporary colostomy for bowel rest, followed by resection of affected bowel segment Prognosis Sx eliminated in ± 90% of Pts with surgery; outcomes better with early interventionmeg·a·co·lon
(meg'ă-kō-lŏn)megacolon
Enlargement (hypertrophy) and widening (dilation) of part or all of the COLON associated with severe and intractable CONSTIPATION. Megacolon may be CONGENITAL or acquired. Congenital megacolon is an AUTOSOMAL RECESSIVE condition caused by the local absence of the nerves responsible for PERISTALSIS.Megacolon
meg·a·co·lon
(meg'ă-kō-lŏn)megacolon
- noun
Words related to megacolon
noun an abnormal enlargement of the colon
Related Words
- colon
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