Hirschsprung disease (HD) is a motor disorder of the colon caused by the failure of neural crest cells (precursors of enteric ganglion cells) to migrate completely during intestinal development. The resulting aganglionic segment of the colon fails to relax, causing a functional obstruction. In the majority of patients, the disorder affects a short segment of the distal colon, with a transition zone in the rectosigmoid. In other patients, the aganglionosis involves longer segments of the colon; in rare cases, the small bowel may also be involved.
HD occurs in approximately 1 in 5000 live births, with an overall male:female ratio of 4:1. When the entire colon is involved, the gender ratio more nearly approaches 1:1 .
This topic review focuses on emergency complications of HD, the most important of which are intestinal obstruction and Hirschsprung-associated enterocolitis (HAEC). Colonic volvulus, a rare complication, also is discussed. The pathogenesis, diagnosis, and clinical management of HD are presented separately. (See "Congenital aganglionic megacolon (Hirschsprung disease)".)
ACUTE OBSTRUCTION IN THE NEONATE
HD accounts for a substantial proportion of cases of neonatal bowel obstruction . Infants who become symptomatic during the first few days of life typically present with failure to pass meconium (present in about 95 percent of neonates with HD), abdominal distension, vomiting (which may be bilious or feculent), and other signs of intestinal obstruction [1,3]. Their clinical condition may deteriorate rapidly unless they are treated promptly. Most newborns with HD can be resuscitated and stabilized by nonoperative means, allowing for a full diagnostic work-up and definitive elective surgery. Emergency surgery is seldom needed, and exploratory laparotomy in undiagnosed cases of HD is to be avoided. Those who present later in infancy have similar symptoms, but are less likely to develop acute obstruction. (See "Congenital aganglionic megacolon (Hirschsprung disease)", section on 'Clinical features'.)
Occasionally, infants with undiagnosed HD may present with Hirschsprung-associated enterocolitis (HAEC), which is discussed below. The clinical presentation includes fever, lethargy, anorexia, vomiting, abdominal distension, and diarrhea; an explosion of gas and liquid stool may occur following digital rectal examination. Because HD is increasingly diagnosed in the first few months of life, fewer children present with HAEC than in the past. Most cases of HAEC occur after a pull-through procedure, as discussed below. (See 'Enterocolitis' below.)