Pathophysiology
1) congenital absence of enteric neurons (ganglions) in rectum and distal colon 2) result of failure of migration of neural crest cells
Signs and Symptoms
1) usually presents shortly after birth but occasionally does not become apparent until later in childhood or adolescence if aganglionic segment is very short 2) massive abdominal distention 3) absent or infrequent bowel movements 4) failure to thrive 5) piebaldism (white spotting of skin)
Characteristic Test Findings
Biopsy – best diagnostic test is a series of full-thickness rectal biopsies
Associated Conditions
1) mutations in RET gene on 9q31 (autosomal dominant form) 2) mutations in endothelin-beta-receptor gene (autosomal recessive form) 3) MEN-2A
Histology/Gross Pathology
aganglionic segment remains permanently contracted with dilated proximal colon that is normal
Inheritance/Epidemiology
1) more common in males 2) exists in both autosomal dominant and recessive forms
Treatment
surgical procedure using a “pull-through” technique to bring normally innervated bowel to anastomose to rectum
Tips for USMLE
if question mentions a 6 day-old boy who has not had a stool since birth, who has a distended abdomen, and who has a dilated distal colon on abdominal radiograph, think Hirschsprung’s
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