Most children with constipation have functional constipation , a condition related to a maladaptive response to an uncomfortable defecation. A small proportion of children with constipation have symptoms unresponsive to aggressive medical and behavioral therapy which are severe enough to dramatically affect quality of life. In constipated children, especially in the presence of fecal incontinence, the chronicity of the symptoms can be very frustrating and may lead to distrust of the medical team and loss of self-esteem for the child. Colonic manometry is indicated for the evaluation of such children in order to discriminate normal from abnormal colonic motor function [28, 29] which may be associated with an underlying colonic neuromuscular disease (Fig. 9.5). This information can then be used to guide management [30]. Resection of colonic segments found to have abnormal motor function leads to improvement in symptoms [31, 32]. Interestingly, there seems to be little or no correlation between manometric findings and histopathologic abnormalities, suggesting that our current ability to study the morphology and function of the enteric neuromusculature is limited [33].

A study by Villareal et al. used HAPC as a marker for intact neuromuscular colonic function [34]. The colonic manometry pattern, namely, the failure to demonstrate colonic HAPC, directed the providers to the formation of a diverting ostomy (ileostomy or colostomy). In patients who had evidence of a dilated colon with abnormal motility patterns, repeat manometry testing after a period of decompression (5–30 months) led to an improved motor function. Aspirot et al. evaluated the effect of chronic use of antegrade enemas on colonic motility in children and adolescents with severe constipation [35]. All children with abnormal manometry prior to cecostomy placement showed improvement in colonic motility after using antegrade enemas for at least 1 year. Colonic manometry may also be used to predict clinical response to antegrade enemas. Retrospective studies have indicated that patients with HAPC and an intact gastrocolonic response are more likely to have a satisfactory outcome when receiving antegrade enemas [36, 37]. The propagated contractions seem to be essential to propel colonic contents during antegrade irrigation. However, the motor response is still not a guarantee for success, as even some patients with intact HAPC have had a poor outcome, indicating that motility pattern is important, but there are additional factors, such as compliance with the antegrade enema schedule and anorectal and pelvic floor function, possibly playing a role.

Chronic intestinal pseudo-obstruction (CIPO ) is a heterogeneous group of disorders that vary in cause, severity, course, and response to treatment. Di Lorenzo et al. studied patients with CIPO and found a subgroup of patients with chronic constipation as part of their CIPO symptomatology who had abnormal HAPC, absent gastrocolonic response, or complete lack of identifiable colonic motor activity [38]. A thorough manometric evaluation including colonic manometry needs to be performed during the evaluation for possible isolated small bowel or multivisceral transplantation in children with CIPO, in order to assess which organs need to be transplanted and if a permanent diverting ileostomy will be needed [39].

After resection of the abnormally innervated bowel in Hirschsprung’s disease, a large percentage of patients continue to struggle with abnormal defecatory function [40]. Our approach to these patients, in collaboration with the surgical team, is to first evaluate for anatomical abnormalities, presence of a residual aganglionic zone, absence of dentate lines due to iatrogenic damage, and quality of anal sphincter function. A contrast enema is used to assess the anatomy and rule out obstructive Soave cuff, bowel stricture, or colonic twist. That is followed by an anorectal manometry , an examination of the anorectal area under general anesthesia, and a repeat full thickness biopsy to assess anal sphincter basal pressure, integrity of the anal canal, and presence and quality of ganglion cells, respectively. If necessary, colonic manometry is then performed for further evaluation. The findings on colonic manometry testing may be classified into four groups, each associated with different physiology [41]. Each category directs different therapy: (1) The first group of patients has HAPC which progress through the neorectum all the way to the anal verge. The amplitude of the HAPC exceeds that of the voluntary contraction of the external anal sphincter. The result is incontinence or rectal pain as the patient attempts to retain the stool. (2) The second group has normal colonic motility with fear of defecation and stool withholding. The negative experience related to attempted defecation before surgical removal of the aganglionic segment or in the postoperative period may result in fecal retention. Identification of normal colonic manometry pattern in these children provides reassurance in the diagnosis and more confidence in the behavioral and medical treatment plan. (3) Abnormal colonic manometry with lack of HAPC, poorly propagating HAPCs, or simultaneous increases in pressure in the distal colon (Fig. 9.5) may be due to a neuropathic motility disorders proximal to the aganglionic segment, possibly associated with intestinal neuronal dysplasia [42] or with a common cavity phenomenon. (4) Finally, a small number of patients with defecation disorders postsurgery for Hirschsprung’s disease have normal colonic motility and a hypertensive anal sphincter. Successful treatment options for this subset of patients have included myectomy, which leads to irreversible destruction of the internal anal sphincter and potential risk of incontinence, and botulinum toxin injection into the hypertensive anal sphincter without the risk of permanent sphincter damage but with the need for repeated injections [43–45]. Similar findings have been described in children with continence disorders after anorectal malformations repair. Heikenen et al. have reported that propagation of excessive numbers of HAPCs into the neorectum as well as internal anal sphincter dysfunction can contribute to fecal incontinence in these children [46].

A limitation of traditional colonic manometry studies is the duration of the study. There is a well-established circadian variation in colonic motility which is missed during short studies [24, 47–49]. Twenty-four-hour colonic manometry has been proposed as a more informative test which evaluates a time period felt to be more representative of the normal patient’s environment and eating and sleeping patterns. It has been performed in children using water-perfused probes [50], but it is best done using solid-state catheters which do not confine the patient to a restricted environment. Solid-state probes have been placed via colonoscopy with clips adhering to multiple sites of the colonic wall. The patient is allowed to ambulate, eat, and defecate in a hospital setting for 24 h with continuous manometric measurement. It is unclear how much the additional information collected during a 24-h study changes clinical management compared to a shorter study with meal ingestion and pharmacological stimulation.

This tool has been approved by the US Food and Drug Administration (FDA) for measurement of gastric emptying and whole gut transit time. Once swallowed, this fairly sizable capsule (diameter and length similar to a video capsule) is capable of measuring intraluminal pH, pressure, and temperature throughout the entire gastrointestinal tract. Data is transmitted to a data receiver and downloads to a computer for analysis. Gastric emptying is measured by timing the point from ingestion to the point where the pH rises above pH6, indicating that the capsule has left the acid environment of the stomach and has entered the more neutral pH of the duodenum [51]. Because it has a single pressure measurement, propagation of motor activity cannot be defined. Wireless pH motility capsule has been found to be useful in evaluating colonic transit and has been validated in adults as an alternative to radiopaque markers as a tool to assess colonic transit [52]. The exact role of the wireless pressure capsule in the evaluation of children with possible colonic dysmotility is still under investigation.