Diagnosis with differential

For the diagnosis of Hirschsprung's disease, the subject's history is very important. The crucial elements to obtain are: the age of the appearance of symptoms; whether the passage of meconium has been normal or delayed; and whether the child presented with episodes of functional intestinal obstruction. In addition, a functional (idiopathic) megacolon must be ruled out. A clinical comparison between functional and congenital megacolon is shown in Table 17.1. When the history (early onset of constipation, absence of fecal soiling) and/or the physical examination (empty rectal ampulla) suggests an organic cause, anorectal manometry should be performed.

Anorectal manometry evaluates the response of the internal anal sphincter to inflation of a balloon in the rectal ampulla.17 When the rectal balloon is inflated, there is normally a reflex relaxation of the sphincter. The rectoanal inhibitory reflex is absent in patients with Hirschsprung's disease; there is no relaxation, or there may even be paradoxical contraction of the internal anal sphincter (Figure 17.2). Anorectal manometry is particularly useful when the aganglionic segment is short and the results of radiological or pathological studies are equivocal.

Barium enema is helpful in the assessment of a transition zone between aganglionic and ganglionic bowel, and in giving an estimation of the length of an aganglionic segment. Demonstration of the transition zone is easier if no effort is made to cleanse the bowel (Figure 17.3). In the newborn, dilatation of the proximal ganglionic bowel may not have developed and radiological diagnosis may be more difficult. The sensitivity and specificity for recognition of a transition zone have been reported to be 80% and 76%, respectively.18 The barium enema may not show a transition zone in cases of total colonic Hirschsprung's disease, or may be indistinguishable from cases of functional constipation when ultrashort-segment Hirschsprung's disease is present.

Nevertheless, the diagnosis is based on histological evidence. Since the mid-1970s,

Table 17.1 Differentiating types of megacolon in children

Functional

Colonic

fecal

neuromuscular

Signs and symptoms

retention

disorders

Soiling

common

rare

Obstructive symptoms

rare

common

Large-caliber stools

common

rare

Stool-withholding behavior

common

rare

Enterocolitis

never

possible

Associated upper-gastrointestinal symptoms

never

common

Symptoms from birth

rare

common

Localization of stools

rectum

rectal and

Hirschsprung Disease Rectal Manometry

[ xlernal sphincter

Figure 17.2 Anorectal manometry in a 2-month-old boy with functional constipation (a). Note that the distension of a rectal balloon with air for 1 s produces a decrease of anal pressure (rectosphincter reflex). (b) Anorectal manometry in a 3-month-old boy with Hirschsprung's disease. Distension of a rectal balloon with air for 1 s produces no decrease of anal pressure.

[ xlernal sphincter

Figure 17.2 Anorectal manometry in a 2-month-old boy with functional constipation (a). Note that the distension of a rectal balloon with air for 1 s produces a decrease of anal pressure (rectosphincter reflex). (b) Anorectal manometry in a 3-month-old boy with Hirschsprung's disease. Distension of a rectal balloon with air for 1 s produces no decrease of anal pressure.

Hirschsprung
Figure 17.3 Barium enema showing a long, narrowed segment in a child with Hirschsprung's disease.

demonstration of acetylcholinesterase activity in mucosal biopsies has allowed the non-invasive suction rectal biopsy technique to become the most reliable diagnostic method for aganglionosis.7,8 The histological diagnosis is based on the demonstration of the total absence of ganglionic cells in the affected segment of the intestine, with an overgrowth of large nerve trunks in the intermuscular and submucosal zones (Figures 17.4 and 17.5).19 Two small samples of rectal mucosa and submucosa, taken using the suction rectal biopsy technique, are sufficient for diagnosis. The two pieces must be taken not less than 2 cm above the dentate line, to avoid the physiological hypoganglionic zone, and not more than 5 cm above the dentate line, to avoid missing the diagnosis of a short-segment disease. Acetyl-cholinesterase activity in the normal colon shows only a few fibers in the lamina propria and muscu-laris mucosae; in Hirschsprung's disease there is an increase in thick, knotted acetylcholinesterase-positive nerve fibers in the muscularis mucosae and lamina propria, and hypertrophied nerve trunks in the submucosa.

The hyperplastic nerve trunks in the lamina propria, submucosa and muscularis propria are both adrenergic and cholinergic. Thus, these are extrinsic nerve fibers that are hyperplastic, owing

Dentate Line Rectum

Figure 17.4 Rectal suction biopsy in a child with functional constipation. Note the presence of clusters of neurons in the submucosa and acetylcholinesterase activity showing only a few wispy fibers.

Hirschsprung Acetyl
Figure 17.5 Intense acetylcholinesterase activity in a patient with Hirschsprung's disease. Note the absence of neurons and the increase in thick knotted nerve fibers in the muscularis mucosae and lamina propria. In addition, hypertrophied nerve trunks are visible in the submucosa.

to the lack of intrinsic nerve cell bodies with which they can synapse. There is evidence that the obstruction can be explained on the ground of loss of NANC nerves, especially vasoactive intestinal polypeptide (VIP)-storing nerves, and an increase in sympathetic nerves containing neuropeptide Y.20 Neuropeptide Y exerts strong contractile effects on the rectum.21 These effects, together with the loss of VIP, are a more convincing expla-

nation for the loss of peristaltic activity and the contracted segment in Hirschsprung's disease.

Constipation Prescription

Constipation Prescription

Did you ever think feeling angry and irritable could be a symptom of constipation? A horrible fullness and pressing sharp pains against the bladders can’t help but affect your mood. Sometimes you just want everyone to leave you alone and sleep to escape the pain. It is virtually impossible to be constipated and keep a sunny disposition. Follow the steps in this guide to alleviate constipation and lead a happier healthy life.

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