Hirschsprung's disease

(Harald Hirschsprung 1830 - 1916, Danish physician), congenital absence of the intramural ganglia of the rectum, extending proximally for a variable distance which may involve the entire colon and a portion of the terminal ileum. The aganglionic segment is non propulsive and causes functional intestinal obstruction. Between normal and aganglionic bowel is a zone of hypoganglionosis. Histochemistry shows increased acetylcholinesterase activity in the enlarged nerve fibres observed histologically. The incidence of Hirschsprung's disease is 1 : 5000 live births with a male preponderance of 3 : 1 in short segment but equal sex incidence in long segment disease. There is a recognized increased incidence in Downs syndrome. Clinically, the infants present with failure of or delayed passage of meconium, abdominal distension and vomiting.

Imaging

The typical abdominal radiograph features are those of a distended colon with less small bowel distension and an absence of, or an occcasional fluid level, but the radiograph may be normal or be that of obstruction or show generalised distension (Fig.1). A water-soluble contrast enema with the catheter situated just inside the anal margin shows a narrow non distensible rectum with a transition to dilated meconium or faeces packed colon (Fig.2). The appearances may be subtle if the infant is examined early and faecal loading is not significant. An irregular "saw tooth" appearance of the rectum is a valuable sign (Fig.3). In total colonic Hirschsprung's disease the colon may be micro or of normal calibre and it is the clinical presentation that raises suspicion. Delayed presentation of Hirschsprung's disease is with constipation (Fig.4). At enema the narrow aganglionic distal segment is easily demonstrated. Most infants are diagnosed as neonates in Western society. Enterocolitis may be a fatal complication. Surgical management may be a primary curative procedure or a relieving colostomy with subsequent definite surgical repair. See Duhamel procedure

HC