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Original Articles: Gastroenterology

Colon Manometry Proves That Perception of the Urge to Defecate Is Present in Children With Functional Constipation Who Deny Sensation

Firestone Baum, Carrie*; John, Anub*; Srinivasan, Kavitha*; Harrison, Prince*; Kolomensky, Andrew*; Monagas, Javier*; Cocjin, Jose; Hyman, Paul E.*

Author Information
Journal of Pediatric Gastroenterology and Nutrition: January 2013 - Volume 56 - Issue 1 - p 19-22
doi: 10.1097/MPG.0b013e31826f2740
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The prevalence of constipation varies, ranging from 0.7% to 29.6% in children (1). Typically, constipation is related to learned behavior aimed at avoiding a painful or frightening defecation experience (2). Children with constipation, who do not respond to medical therapy, including family education and nonstimulant stool softeners, are referred to pediatric gastroenterologists for further evaluation (2,3). When conventional therapy fails, colon manometry is used to distinguish normal colon motility from neuromuscular disease (4).

Colon manometry testing has been standardized and is performed at a few centers specializing in the care of children with intractable constipation (5). As experience with colon manometry accrued, we learned that a majority of children referred for colon manometry had functional disorders that, before study, were obscured by comorbid features or nonadherence (3). A minority with colon nerve or muscle disease benefited from surgical procedures such as appendicostomy (6) and subtotal colectomy (7).

Psychosocial, developmental, and emotional problems that affect acquisition of proper toilet skills may predispose children to the development of functional constipation (3). Our hypothesis was that colon manometry may play a role providing not only objective data on motility but also observations about emotional and family issues affecting functional constipation. Colon manometry testing, like any procedure, may be expected to be a stressful time that may amplify maladaptive behaviors. For example, many children with constipation state that they feel no urge to defecate, suggesting that constipation may be associated with a sensory disorder (8,9). This apparent absence of sensation has been attributed to dilation of the rectum or abnormalities in sensory nerve function (10,11); however, in the course of performing colon manometry, we observed that children appeared to change their behavior in association with high-amplitude propagating contractions (HAPCs), which are a biomarker for colon neuromuscular health. The children's behavior during HAPCs varied from requesting use of the bedside commode to stoic grimacing with retentive posturing, to screaming with fear and pain and covering themselves with a sheet to hide. Based on these preliminary observations, we considered the possibility that children with chronic constipation sensed HAPCs even though they reported the absence of an urge to defecate. We hypothesized that the children who deny sensation do so to avoid dealing with the problem, use denial as a defense mechanism, or lack the self-awareness to recognize natural body signals to achieve proper toilet learning.


Consent to review patient charts was obtained from the Louisiana State University Health Sciences Center and the Children's Hospital of New Orleans. The senior author (P.E.H.) kept records from all of the patients undergoing colon motility studies during the preceding 20 years. We included 173 subjects previously reported (3). We identified 410 patients referred from other pediatric gastroenterologists and surgeons for colon manometry and reviewed the data. We collected details from records including reasons for referral, frequency of defecation, character of the stools, fecal incontinence, abdominal pain, the manometry diagnosis, and the final diagnosis. Although there was no organized questioning regarding sensation, the clinician noted when the subject or caretakers stated that there was an absence of sensation to defecate, or an inability to feel fecal incontinence.

Colon manometry was performed according to published criteria (5). Subjects were prepared for colonoscopy the day before testing with a colon cleanout regimen. On the day of testing, consent was obtained from parents. We used intravenous propofol and midazolam to facilitate endoscopic placement of a water-perfused manometry catheter with recording sites 10- to 15-cm apart. The most proximal recording site was placed in the right colon. Placement was confirmed using brief fluoroscopy. When the subject awoke, we began recording colon pressures in 7 or 8 recording sites, first for 1-hour fasting, then for 1 hour after the subject's choice of meal containing fat and protein, then for at least 40 minutes after 0.2 mg/kg bisacodyl, to a maximum of 10 mg placed through the manometry catheter central lumen into the right colon. Normal motility had 3 features: high-amplitude propagating contractions, an increase in motility following a meal, and the absence of discrete abnormalities such as unremitting contractions in 1 recording site. A senior author (P.E.H. or J.C.) was present for the duration of testing.


The group of 410 subjects was divided into categories by reason for referral as shown in Table 1. A majority of subjects, 217, were referred to determine the cause for persistent constipation. Other subjects were referred for abdominal pain, fecal incontinence, pseudoobstruction, assessment of anorectal malformations, and persistent defecation disorders following surgery for Hirschsprung disease. Subjects with Hirschsprung disease were referred after successful surgery to determine the cause for persistent symptoms of incontinence, diarrhea, constipation, or abdominal pain. Subjects with pseudoobstruction were referred to determine the physiology associated with their symptoms.

Table 1
Table 1:
Referring diagnosis in subjects referred for colon manometry

Of the patients referred for colon manometry, 64% were male (N = 261). The average age was 7.6 years with a range from 0.25 to 26 years. A majority (67%) had normal studies (Fig. 1). Of those patients with normal studies, 150 of them met symptom-based criteria for functional constipation and had a final diagnosis of functional constipation. There were no significant age or sex differences in patients with functional constipation compared with patients with other diagnoses. Of the patients with functional constipation, there were 85 boys and 65 girls, with ages ranging from <1 to 19 years (median 6.2 years). Others who were not diagnosed as having functional constipation but had normal studies met criteria for irritable bowel syndrome or another pain disorder. Symptoms for the patients with functional constipation are listed in Table 2. They must have 2 or more of the following: 2 or fewer stools per week and either hard/very hard stools or painful stools; passage of very large stool; stool retention once per week or more often; history of a large fecal mass in rectum; soiling once per week or more often; and does not meet criteria for irritable bowel syndrome (12).

Final diagnoses of subjects who underwent colon manometry.
Table 2
Table 2:
Symptoms in subjects with functional constipation

Progress notes or letters to the referring physicians documented statements from the child or a parent that suggested sensory abnormalities in 56 subjects: the child was unable to sense an urge to defecate; and/or did not feel incontinence; had abdominal pain but did not connect those sensations with the need to defecate (Fig. 2).

Summary of functional constipation subjects reporting sensations or lack of sensations. In this retrospective study, not all of the subjects reported whether there was sensation or an urge to defecate. Subjects who misreported stated no sensation, no urge to defecate, or abdominal pain at the time of HAPCs.

HAPCs appeared spontaneously or after bisacodyl in all of the patients with a final diagnosis of functional constipation. Thirty of 150 subjects with functional constipation had spontaneous HAPCs, either during fasting (n = 3) or after a meal (n = 27). Only 7 subjects recognized the spontaneous HAPCs and defecated, ending the test session. A total of 23 subjects did not respond to the HAPC, and those subjects were treated with bisacodyl to stimulate a series of HAPCs. There were a range of behaviors associated temporally with the initial HAPC from requests to use the bedside commode or defecation into a diaper, to stoic retentive posturing, to screaming. When queried, subjects with retentive posturing initially denied sensation. Using words that the child and family could understand, the examiner guided each child through the HAPC, explaining how the lines on the computer screen represented the colon pushing stool toward the end of the digestive tract. The clinicians explained that abdominal pain was a signal to defecate and that if the child chose not to relax their bottom, there was pain, but if the child relaxed, there was a bowel movement and a pleasant sensation, a relief. Subjects were instructed to relax their bottoms when they felt the sensation associated with HAPCs on the computer screen. Many subjects first ignored the explanation, but with subsequent HAPCs, each patient who had initially denied an urge to defecate or reported abdominal pain agreed that there was sensation, and asked to defecate on the bedside commode or into the diaper. All of the 56 subjects who initially denied sensation or the urge to defecate recognized the urge to defecate and had successful defecation by the end of the study. Of the 150 patients with functional constipation, 3 failed to acknowledge sensation or defecate despite bisacodyl-stimulated HAPCs. These subjects had bowel movements shortly after the study was completed. At the end of the study, nearly all of the patients acknowledged sensation and the urge to defecate. Nearly all of the parents or caretakers conveyed understanding that the studies were normal.


Colon manometry can be useful not only for pressure measurements but also for psychological observations and biofeedback. Performing colon manometries requires a time commitment on the part of the physician and the patient/family. The time can be used not only to learn about the physiology of the gastrointestinal tract but also to observe interactions between the patient and the caregiver. The time spent with the patient and family during the test sessions facilitated the clinician learning important brain–gut interactions that would be missed by a clinician whose agenda is exclusively a review of colon contractions. Manometry contains the objective answers that are most important when there is enteric neuromuscular disease; however, behavioral observation provides the important answers about coping skills and family dynamics when the manometry is normal but the child is suffering.

This study demonstrated again that the majority of children referred for colon manometry have normal studies (3,4). Children who were diagnosed as having functional constipation met symptom-based Rome criteria (12), and during the study may have demonstrated retentive posturing, grimacing at the time of HAPCs, or denial of sensation of the urge to defecate. These patients often had successful defecation by the end of the study.

Most children with functional constipation responded to education about their condition and stool softeners to achieve painless defecation (13). Patients with functional constipation are referred for colon manometry after failing therapies (4). Children with functional constipation may deny the urge to defecate and/or sensation of incontinence, or their parent may state that the child cannot feel. Parents may misinterpret retentive posturing as straining to push stool out, and not holding stool in (3). During colon manometry, the clinician used HAPCs as an opportunity to teach the caregivers and child that the HAPC was normal, and that what the child was feeling was the normal sensation associated with the need to defecate. By completion of the study, nearly all of these children were convinced that they had normal, healthy colons and could achieve proper toilet hygiene if they relaxed their bottom at the time of the HAPCs. Colon manometry can be a powerful tool for biofeedback and reassurance. It is an opportunity for the clinician to show the patient and family that the child is healthy, that the condition is not dangerous, and that they can get better if they are ready to make an effort to do so.

Nonverbal children cannot discuss their sensory experience; however, constipated infants were referred to discern the presence or absence of colonic neuromuscular disorders. If their studies were normal, we placed them into the functional constipation category. We did not attempt biofeedback in nonverbal children.

Colon manometry is an opportunity to observe the relationships and behaviors between the caregivers and the child in a stressful setting. It can also be an opportunity to witness and document psychopathology in either the caregiver or the patient. Physicians spent 2 to 3 consecutive hours with the subject and caregivers. One of the goals of the encounter was to establish a rapport with child and family. The clinicians hoped that rapport was achieved by listening intently and asking detailed questions. At the conclusion of testing, physicians gave the child and parents explanations of the diagnosis and management. The physician also offered contact information including e-mail addresses for continued availability at the time of discharge. The physician asked each participant if there were any questions at the end of the session and typically there were no questions. Rarely, after the physician left the room, the caregiver voiced a complaint to the nurse that they were not told what was wrong with the child. In such a case, the study was an opportunity for the clinician to see that there is a barrier in the parent to understanding that the child is normal. The same amount of time was spent with each family, so for those families that left feeling unsatisfied, there was another reason for their reaction. For satisfied families, the manometry served as reassurance and an opportunity for biofeedback, which was invaluable.

Children may fail therapy for a variety of reasons including parents unable or unwilling to provide consistent support, a child's communication problems, which interfere with the education necessary to understand the condition, nonadherence to treatment, or intellectual or psychiatric issues preventing proper toilet hygiene. Parents can teach and model the proper skills needed to achieve successful toilet training, but at some point, the child's willingness to exercise control in the behaviors is necessary. One possibility is that self-efficacy is a key to children becoming competent in toilet behaviors.

Self-efficacy is a belief system that determines how people feel regarding their abilities to accomplish certain tasks and acts as a motivator for certain behaviors. Having a sense of self-efficacy enables increased accomplishment, whereas those with poor self-efficacy have lower aspirations and more adverse outcomes. An effective way of achieving a higher sense of self-efficacy is by mastering tasks and experiences. Similarly, self-efficacy is enhanced through witnessed experiences. Watching someone else succeed teaches a child that he/she too can succeed. It is possible that children who fail toilet training develop a poor sense of self-efficacy, which contributes to the development of constipation (14).

There are stages of psychosocial development for every healthy human being (15). In each stage, the individual is faced with challenges that must be confronted and mastered. Each stage builds on the previous one (although it is not necessary to master one before moving on the next). In the toddler years, a child gains control of his or her surroundings and masters a variety of personal skills. These skills include feeding themselves, walking, talking, and fine motor development, as well as toilet training. Erikson described gaining control of bowels as a violent time. At this time children learn what Erikson (15) called “autonomous will” and this stage involves muscular maturation, verbalization, and discrimination of various internal and external sensory cues. While acquiring these skills, children learn self-esteem and autonomy. This developmental stage involves reconciling conflicting ideas; one of holding on and one of letting go. If toilet training is not achieved or the process involves negative experiences including being shamed into the process, shame and doubt will persist. Shame, according to Erikson, is an infantile emotion and leads to secretive behavior, with the child attempting to hide inappropriate activities. Therefore, children who failed toilet learning may deny sensations of the urge to defecate and have persistent problems with constipation and proper toilet hygiene, all the while having shame and embarrassment (15).

If the child denies that there is a problem, it is no longer part of his or her reality. It is possible that the child dissociates the sensations before defecation so that HAPCs are perceived as abdominal pain and not as a call to defecate. It has been surmised by others that there is reduced sensation because of rectal dilation that occurs as a result of longstanding constipation and persistent stool in the rectal vault (9–11); however, van den Berg et al (16) demonstrated that increased rectal compliance and rectal distention were not associated with treatment failure for functional constipation. Additionally, the change in rectal compliance after 1 year was not significant in patients with reported hyposensitivity.

Those children who deny sensation, when we tell them we know they can feel it, often change their minds and agree with the examiner. The colon manometry therefore allows for an opportunity for biofeedback, an opportunity to help the child make a connection between the HAPC and the urge to defecate, regardless of the reasons for misinterpretation of normal HAPCs.

There are a number of flaws with this retrospective study. We relied on the information obtained in charts and had no access to the patients at this time. There was no formal questioning regarding sensation of the urge to defecate, so we may have underestimated the number of children who misreport. We did not test the anal wink to test sensation but relied on child or parent report. Finally, there was no follow-up of these patients. Future studies may prospectively examine the role of development and self-efficacy on the expression of functional constipation.


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biofeedback; gastrointestinal motility; pediatrics

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