Chapter 34 Hirschsprung’s Disease
PATHOPHYSIOLOGY
Hirschsprung’s disease, or congenital aganglionic megacolon, is a congenital anomaly characterized by the absence of ganglion cells in the rectum and extending proximally to the colon and, rarely, the small intestines. The absence of ganglion cells causes a lack of enteric nervous system stimulation, resulting in the inability of the internal sphincter to relax and thus increase intestinal tone, which in turn causes decreased peristalsis. Intestinal contents are propelled to the aganglionic segment; because of the lack of innervation, fecal material accumulates, which results in dilation of the bowel (megacolon) proximal to the aganglionic area. Along with the lack of peristalsis, there is loss of the rectosphincteric reflex; namely, the rectal sphincter fails to relax, which prevents the normal passage of stool and thereby contributes to the obstruction. Exact etiology is not known; however, genetics and environmental factors are suspected to play a role. Hirschsprung’s disease generally manifests during the neonatal period; however, it may appear at any age.
SURGICAL MANAGEMENT
Surgical treatment of Hirschsprung’s disease is a two-stage process. Initially, a temporary colostomy is performed (1) to decompress the bowel and divert the fecal contents, and (2) to allow the dilated and hypertrophied portion of the bowel to regain normal tone and size. When the bowel regains normal tone, after approximately 3 to 4 months (infants should be between 6 and 12 months of age or weigh 8 to 10 kg), a rectal pull-through procedure is performed in which all aganglionic bowel is removed and the normal bowel is reconnected to the anus. The colostomy is also closed during the second surgery.
NURSING ASSESSMENT
See the Gastrointestinal Assessment section in Appendix A.
