aganglionic megacolon
megacolon
[meg″ah-ko´lon]
Hirschsprung disease
A condition of infant onset characterised by the absence of myenteric nerves in the distal colon, extending proximally from the anus for a variable distance. It affects an estimated 1:5000 live births, and is more common in males (male:female ratio, 4:1); up to 10% have Down syndrome.Clinical findings
Failure to pass meconium or stool in first 24 hours post-partum; abdominal distention; vomiting; constipation at birth. Peristalsis is absent in aganglionic segment, causing proximal pseudo-obstruction and gross dilatation, enterocolitis and perforation. In older children, Hirschsprung disease is characterised by chronic constipation, abdominal distention and stunted growth.
Diagnosis
By rectal suction biopsy; must include submucosa, taken at least 2 cm above pectinate line.
Management
Resection of aganglionic segment, guided by intraoperative frozen sections from myenteric plexus.