Failure of neural crest cells to migrate leads to:
a. Hirschsprung's disease occurs in 1 out of every 5000 live births and is characterized pathologically by absent ganglion cells in the myenteric (Auerbach's) and submucosal (Meissner's) plexus.
b. This neurogenic abnormality is associated with muscular spasm of the distal colon and internal anal sphincter resulting in a functional obstruction.
c. Hence, the abnormal bowel is the contracted, distal segment, whereas the normal bowel is the proximal, dilated portion.
d. The area between the dilated and contracted segments is referred to as the transition zone. In this area, ganglion cells begin to appear, but in reduced numbers.
e. The aganglionosis always involves the distal rectum and extends proximally for variable distances.
f. The rectosigmoid is affected in roughly 75% of cases, splenic flexure or transverse colon in 17%, and the entire colon with variable extension into the small bowel in 8%.
g. The risk for Hirschsprung's disease is greater if there is a positive family history and in patients with Down syndrome.
b. Failure to pass meconium in the first 24 hours is a highly significant and cardinal feature of this condition.
c. In some infants, diarrhea may develop as a result of enterocolitis.
d. The diagnosis of Hirschsprung's disease may also be overlooked for prolonged periods. In these cases, older children may present with a history of poor feeding, chronic abdominal distention, and a history of significant constipation.
e. Because constipation is a common problem among normal children, referral for surgical biopsy to exclude Hirschsprung's disease occurs relatively frequently.
f. Enterocolitis is the most common cause of death in patients with uncorrected Hirschsprung's disease and may manifest as diarrhea alternating with periods of obstipation, abdominal distention, fever, hematochezia, and peritonitis.