Pediatric Colonic Motility Disorders Workup

Updated: Jul 05, 2016
  • Author: Nelson G Rosen, MD, FACS, FAAP; Chief Editor: Harsh Grewal, MD, FACS, FAAP  more...
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Workup

Laboratory Studies

Currently, no blood tests are specifically useful in the diagnosis and treatment of pediatric colonic motility disorders. If a patient presents with distention and abdominal pain and has gone several days without a bowel movement, a complete blood count should be obtained. The presence of leukocytosis suggests an acute etiology (eg, appendicitis or ovarian cyst rupture) rather than chronic constipation.

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Imaging Studies

All patients should undergo baseline posteroanterior (PA) and lateral sacral radiography to ensure that they do not have sacral malformations, which could suggest spinal dysraphism or a presacral mass as the underlying cause. Children with an abnormal sacrum should undergo spinal ultrasonography if they present before age 6 months or should undergo magnetic resonance imaging (MRI) if they present after age 6 months. Abdominal radiography and contrast enema study are the main diagnostic modalities.

A single-view flat abdominal image is the most useful image in the workup of patients with a colonic motility disorder. Retained stool in the rectum, the sigmoid, and the left side of the colon is a pertinent finding. Stool in the right side of the colon is meant to be passed the next day; therefore, this finding is irrelevant. However, persistent left-side stool is a sign of incomplete emptying.

Radiographic findings should be considered in the context of when the image was obtained. If the image was obtained many hours after the patient's last bowel movement, the appearance of stool almost ready to come out is expected. If the image was obtained not long after a bowel movement, this finding represents incomplete evacuation.

Contrast enema is an extremely important examination and should be performed in all children who have problems with colonic motility to assess the size of the colon, to see if any segments are dilated, and thus to determine if hypomotility is present.

If the patient is a newborn and the diagnosis in question is Hirschsprung disease, a contrast enema study is classically performed with barium. In children with suspected meconium ileus or a meconium plug or in older children with constipation, it should always be performed with water-soluble contrast material. Water-soluble contrast material draws water into the stool and helps clean out the impacted stool. Despite this effect, the contrast agent may not be cleared for days; if the contrast agent persists for days, it is a sure sign of severe constipation.

Many gastroenterologists perform transit studies, in which patients ingest radiopaque markers that are then followed through the intestinal tract by means of radiography. These studies may be useful in determining where the markers accumulate over time and whether any segments of the colon exhibit hypomotility.

Cinedefecography involves a real-time movie taken of the patient during the act of defecating a thick barium paste. The anorectal angle is determined, and the motion of all of the pelvic musculature is examined. This study is rarely performed in children, and its findings do not help in targeting specific therapies.

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Manometry

Anorectal manometry, which in this context requires special equipment and personnel with expertise in children, consists of inserting a catheter with attached pressure sensors into the anus and then assessing anal function by measuring the pressures generated during squeezing and passive stretching. The rectoanal inhibitory reflex is seen when the internal anal sphincter relaxes during passive distention produced by inflating a balloon in the rectum. This reflex is classically absent in Hirschsprung disease.

Clinicians at centers with extensive expertise in anorectal manometry often use this test for first-line screening in infants and children after the neonatal period. Although this test may be helpful in some settings, it is of limited use in evaluating idiopathic constipation. Results of anorectal manometry alone are insufficient as the only indication for surgical treatment of Hirschsprung disease.

Total colonic manometry is similar to anorectal manometry but is used to measure pressures throughout the entire colon by means of a long catheter, which is placed during endoscopy and with the child under sedation. [5, 6] This procedure may be useful when colonic dysmotility is severe and when the diagnosis of pseudo-obstruction is in question. Total colonic manometry is performed in few centers and has yet to become a mainstream study.

There is growing interest in high-resolution colonic and anorectal manometry to assess motility. However, few studies of this approach have been done in children, and it is not yet clear whether it affords any significant advantage over conventional monometry in this setting. [7]

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Histologic Findings

Histologically, Hirschsprung disease is characterized by the absence of ganglion cells, nerve-bundle hypertrophy, and increased acetylcholinesterase staining.

In patients with idiopathic constipation, biopsy sample findings are normal when conventional histologic techniques are used. Experimental advanced techniques (C-Kit staining and electron microscopy) have been able to demonstrate a deficiency of the interstitial cells of Cajal, which seem to play a vital role as pacemakers of intestinal motility.

Intestinal neuronal dysplasia (IND) is a nebulous condition. Histologic criteria vary. Patients may have giant cells, nerve plexus hyperplasia, increased acetylcholinesterase staining, and various other findings. Special staining techniques may be required to demonstrate these abnormalities. Not all patients with these conditions have all of the findings. This disease entity remains highly controversial.

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