Hirschsprung

Hirschsprung disease, also known as congenital aganglionic megacolon, is a congenital disorder caused by failure of neural crest cell migration to the distal colon. The result is absence of ganglion cells in the submucosal and myenteric plexuses, most commonly in the rectosigmoid region. This lack of autonomic innervation causes a nonrelaxing distal segment and a functional obstruction, with proximal bowel dilation.

In newborns, symptoms include failure to pass meconium within 24 to 48 hours, abdominal distension, vomiting, and sometimes toxic symptoms. Older infants and children may have chronic constipation, episodic fecal incontinence, poor weight gain, and abdominal distension. Episodes of enterocolitis can be life-threatening.

Diagnosis is based on clinical suspicion supported by investigations. A rectal suction biopsy showing absence of ganglion cells and hypertrophic nerve fibers is diagnostic. Contrast enema can show a transition zone between a narrow aganglionic distal segment and a dilated proximal colon. Anorectal manometry may aid in older infants by demonstrating lack of relaxation of the internal anal sphincter.

Treatment involves surgical removal of the aganglionic segment with a pull-through of normally innervated bowel. Several techniques exist (Swenson, Soave, Duhamel) and can be performed as open or minimally invasive procedures. In neonates, a staged approach with temporary diverting ostomy may be used.

Prognosis is generally good after correction, but children require long-term follow-up for bowel function. Complications include enterocolitis, anastomotic stricture, constipation, and incontinence. Hirschsprung disease affects about 1 in 5,000 live births and shows male predominance; about a third may have associated congenital anomalies or syndromes, including Down syndrome. It is named after Harald Hirschsprung, who first described the condition in the late 19th century.