Archives of Disease in Childhood 1994; 71: 186-193

ORIGINAL ARTICLES

Is encopresis always the result of constipation?

M A Benninga, H A Buller, H S A Heymans, G N J Tytgat, J A J M Taminiau

AbstractEncopresis is often the result of chronicconstipation in the majority of paediatricpatients. In clinical practice, however,encopresis is also seen without consti-pation and it is unkown whether thesetwo clinical variants are based on similaror different pathophysiological mech-anisms, requiring different therapeuticapproaches. We analysed clinical symp-toms, colonic transit time (CTI), orocae-cal transit time (OCTT), anorectalmanometric profiles, and behaviouralscores. Patients were divided into twogroups, one consisted of 111 children withpaediatric constipation, and anothergroup of 50 children with encopresis and/orsoiling without constipation.

Significant clinical differences inchildren with encopresis/soiling existedcompared with children with paediatricconstipation regarding: bowel movementsper week, the number of daytime soilingepisodes, the presence of night timesoiling, the presence and number ofencopresis episodes, normal stools, painduring defecation, abdominal pain, andgood appetite.

Total and segmental CTT were signifi-candy prolonged in paediatric constipationcompared with encopresis/soiling, 62-4(3.6-384) and 40 2 (10*8-104-4) hours,respectively. No significant differenceswere found in OCTT. Among the twogroups, all manometric parameters werecomparable, except for a significantlyhigher threshold of sensation in childrenwith paediatric constipation. The defeca-tion dynamics were abnormal in 59o/oand 46% in paediatric constipation andencopresis/soiling, respectively, and weresignificantly different from controls.Using the child behaviour checklist nosignifcant differences were found whencomparing children with psediatric consti-pation and encoprsis/soiling, while bothpatient groups differed significanty fromcontrols.

In conclusion, our findings support theconcept of the existence of encopresis as adistinct entity in children with defecationdisorders. Identification ofsuch children isbased on clinical symptoms, that is,normal defecation frequency, absence ofabdominal or rectal palpable mass, incombination with normal marker studies

and normal anal manometric threshold ofsensation. Thus, encopresis is not alwaysthe result of constipation and can be theonly clinical presentation of a defecationdisorder.(Arch Dis Child 1994; 71: 186-193)

Children with faecal incontinence are notcapable of controlling their bowels. Manydoctors regard it as a trivial symptom whichwill eventually disappear. Apart from theshame and fear of discovery, however, it maylead to social withdrawal, low self esteem, anddepression.1-3 Despite these consequences inchildren, encopresis and soiling have receivedless attention than enuresis.The term encopresis was originally intro-

duced by Weissenberg in 1926 to characterisethe faecal equivalent of enuresis.4 Manyhave tried to define and classify encopresis,but no agreement has been reached. Someworkers divide encopresis into either faecalincontinence with evidence of constipation(psychogenic constipation, psychogenic mega-colon, paradox diarrhoea, or overflow inconti-nence),5-8 so called retentive encopresis, ornon-retentive encopresis. The latter is furthersubdivided into a primary (or continuous)form (faecal incontinence with no evidenceof constipation occunring in children whohave not been toilet trained successfully) andsecondary (or discontinuous) non-retentiveencopresis (occurring in children who werecompletely toilet trained and subsequentlyregressed to incontinence).9 11 In contrast,however, Levine stated that virtually allchildren with encopresis retain stools.' Hesuggested that a plain radiograph of theabdomen often exposed substantial faecalretention, despite a normal history andphysical examination. He therefore consideredthe term 'encopresis without constipation' tobe incorrect.The term faecal incontinence encompasses

encopresis and soiling. The important differ-ence is the amount of faeces lost. These twoterms are often used indistinguishably in pub-lished work. In this study we define encopresisas the voluntary or involuntary passage of anormal bowel movement in the underwear(or other unorthodox locations), after theage of 4 years, occurring on a regularbasis without any organic cause.5 12 13 Thusencopresis is defined on the basis of asign, rather than the presence or absence of

Academic MedicalCentre, Amsterdam,The NetherlandsMA BenIingaH A BillerH S A HeymansJ A J M Taminiau

Department ofGastroenterologyGN J Tytgat

Correspondence to:Dr M A Benninga,Department of Paediatrics,Academical Medical Centre,Meibergdreef 9, 1105 AZAmsterdam, TheNetherlands.Accepted 24 May 1994

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Is encopresus always the result of constipation?

constipation, and reflects defecation in theunderwear. Faecal soiling is defined as theinvoluntary seepage of faeces which is oftenassociated with faecal impaction, and reflectsstaining of the underwear.6 7 12

Encopresis is reported to be responsible for3% of referrals to teaching hospitals and hasbeen noted in 1-3% of those over 4 and in1-2% of 7 year olds.5 13 14-16 The prevalenceamong children of 10-12 years was 1-3% forboys and 0-3% for girls.5

Although faecal incontinence is a commonproblem in paediatric practice, the patho-physiological mechanisms are largelyunknown. Marker studies have shown thatthe total colonic transit time (CTI) in consti-pated children is significantly prolongedcompared with healthy controls.17-'9 Anorectalmanometry in children with constipation andencopresis showed an increased threshold toperceive rectal distention and an inabilityto relax the external anal sphincter duringdefecation.2023To find out whether faecal incontinence

exists in the absence of constipation and tounravel possible different pathophysiologicalmechanisms, we analysed children with consti-pation with or without encopresis/soiling andchildren with encopresis/soiling only.Differences among these patients regardingtheir clinical symptoms, CTT, orocaecaltransit time (OCTT), anorectal manometricprofiles, and scores on the child behaviourchecklist (CBCL) were evaluated.

MethodsSUBJECTSIn this study, 161 otherwise healthy patientswith defecation disorders, aged 5-17 years,were referred between 1991 and 1993 to ourpaediatric intestinal motility unit of a tertiaryacademic teaching hospital. Patients werereferred by general practitioners, school doc-tors, paediatricians, or child psychiatrists.Patients had to fulfil at least two of our fourcriteria of paediatric constipation to participatein the study: (a) stool frequency less than threeeach week; (b) two or more soiling/encopresisepisodes each week; (c) periodic passage oflarge amounts of stool at least once every sevento 30 days; and (d) a palpable abdominal orrectal mass. In addition, all patients wereenrolled with two or more episodes each weekof encopresis or soiling alone without any ofthe other criteria for paediatric constipation.A palpable rectal mass was defined as thepresence of a faecal lump in the rectal ampulla.Known causes of constipation, such asHirschsprung's disease, spina bifida occulta,hypothyroidism or other metabolic orrenal abnormalities, mental retardation, andchildren receiving drugs other than laxativeswere excluded.Each child underwent a complete work up

that encompassed a detailed medical historyand a thorough physical and digital rectalexamination. Specific attention was paid todefecation frequency on the toilet, questionsabout the amount of stools lost in the

underwear (encopresis, soiling), and time ofoccurrence. In addition, transit time studiesand anorectal manometry were performed andthe CBCL was completed. The study wasapproved by the hospital's medical ethicscommittee. Written informed consent wasobtained from patients or their parents, orboth.

Healthy controls for the OCTT test and forthe anorectal manometry were 39 and 15healthy children, respectively. Informedconsent was obtained from the subjects andtheir parents.

ASSESSMENT OF OCT1 AND CTTBecause of poor compliance in childrenregarding the intake of alimentary fibre, nostandardisation was attempted and measure-ment of OCTT and CTT were performed inpatients taking their own customary diet.Treatment with laxatives (pills or enemas) wasalways interrupted at least four days before thestudy. No subject had received antibiotics forat least three months before the test.24

COLONIC TRANSIT TIMETotal and segmental analysis of CCTs werecarried out as reported previously.25 Patientsingested a capsule with 20 radio-opaquemarkers on three consecutive days at 9.00 am.Abdominal radiographs were obtained on thesame time in the morning on day 1 and fourdays after ingestion of the last capsule.Additional abdominal radiographs were takenseven, 10, and 13 days after ingestion of thelast capsule if more than 20% of markers werestill present. Abdominal radiographs wereobtained using a high kilovoltage fast filmtechnique to reduce radiation exposure(estimated surface exposure 0-08 mrad perfilm).

Localisation of markers on abdominal filmsrelied on the identification of bony landmarksas described by Arhan et al.26 Markers werecounted in the right, left, and rectosigmoidregions, and mean segmental transit timeswere calculated as described.25 26 The normalrange for segmental transit times were takenfrom the limits (mean (2 SD)) from a study ofArhan et al in healthy children.26

OROCAECAL TRANSIT TIMEThe method used to study OCTT was asdescribed by van der Kley-van Moorsel et al.27Studies were performed after an overnight fast.End expiratory breath samples were takenbefore the ingestion of 10 g lactulose (20 ml of50% solution) and at 15 minute intervalsthereafter up to a maximum of 240 minutes.28At all time points, measurements consisted oftwo samples taken one minute apart. Thebreath was collected in a 60 ml plastic syringewith a side hole and a mouthpiece at the tipopening.27 The hydrogen content of theexpelled air was measured by the HoekloosLactoscreen27 and expressed in parts permillion (ppm). The OCTT7 was defined as the

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Benninga, Baller, Heymans, Tytgat, Taminiau188

Table 1 Clinicalfeatures ofgroups defined by symptoms. The enties are number (%/o) ormedian (range)

Paediatric constipation Encopresis/soiling(n= I11) (n=50) p Value

Boys 75 (68) 43 (86) 0-02Age 8-0 (5-14) 9-0 (5-17) 0-01Age of onset of symptoms (months)

Is encopresis always the result of constipation?

Table 2 C1T in hours (mean and range)

Paediatnc constipation Encopresis/soiling Arhan*(n= 111) (n=50) (n=23)

Right colon 13-8 (0-60) (p

Benninga, Biier, Heymans, Tytgat, Taminiau

higher in the paediatric constipation groupcompared with the encopresis/soiling group.

In 56 of 111 paediatric constipation patientsthe total CTT' was within the normal limits.26 In22 patients with paediatric constipation withtotal CTT >62 hours a significant delay intransit occurred in the rectosigmoid only,whereas significantly increased transit times inall segments were observed in 14 paediatric con-stipation patients. In the encopresis/soilinggroup 44 patients had a total CTT within thenormal range. In five encopresis/soiling patientswith a total CTT >62 hours, the accumulationof markers occurred in the rectosigmoid.

OROCAECAL TRANSIT TIMEThe OCTT (median and range) in paediatricconstipation, encopresis/soiling, and controlswas 60 (30-180), 60 (30-105), and 60(30-120) minutes respectively. In thepaediatric constipation group eight children(7%) were classified as non-hydrogenproducers, whereas in the encopresis/soilinggroup only two children (40/o) had breathhydrogen peaks 10 ppm abovebaseline values.

ANORECTAL MANOMETRYIn 31 paediatric constipation children withextreme faecal retention, disimpaction withenemas was performed daily during the weekbefore manometry to guarantee an emptyrectal ampulla and to standardise the anorectalmeasurements for all patients. No enemaswere given on the day of manometric measure-ments. The remaining patients required noenemas before manometry. Table 3 shows thatall manometric parameters were comparablebetween the two patient groups, apart froma significantly higher threshold of sensation(p=0008) in children with paediatric con-stipation. Maximum anal resting tone wassignificantly higher in the encopresis/soilinggroup (p=0 04) than controls. Only the paedi-atric constipation group required significantlylarger balloon volumes to provoke a rectal sen-sation (p=0 02) compared with healthy con-trols. In encopresis/soiling patients thisthreshold was even lower than in controls.Significant higher balloon volumes wereneeded in the two patient groups comparedwith control children (p=0-02 and p=0-02respectively) in eliciting the rectoanalinhibitory response. The defecation dynamicswere abnormal in 59% and 46% in the paedi-atric constipation and encopresis/soilinggroups respectively and were significantly dif-ferent from controls (p

Is encopresis always the result of constipation?

in which the rectum is increasingly distendedby abnormally firm faecal contents.' Theinfrequent passage of these hard andlarge amounts of stools induces pain duringdefecation, inhibition of voluntary efforts,and results in abnormal sphincter contractionduring defecation. Finally, chronic rectaldistension causes soiling, sometimes enco-presis, loss of rectal sensitivity, and hencea normal urge to defecate.20 35 36 Levine statedthat in most children with faecal incontinencea plain radiograph of the abdomen wouldunmask extensive faecal retention.' This studyshows that a third of the children referred forfaecal incontinence show*ed no signs of consti-pation. Almost all encop*sis/soiling childrendefecated daily, resulting in significantly fewerconstipation associated complaints - forexample, abdominal pain and poor appetite.Importantly, and in contrast with children withpaediatric constipation, encopresis/soilingpatients exhibited no abnormalities onabdominal and rectal examination. Further-more, no aberrations were found on radio-graphic examination in most encopresis/soiling patients using Barr scores, suggestingthat children with encopresis/soiling form adistinct group of patients.37The existence of night time soiling, the loss

of loose stools in pyjamas, was significantlyhigher in the paediatric constipation groupthan in children with encopresis/soiling. Innearly all instances this was correlated withsevere faecal impaction and extreme prolongedtotal CT (>100 hours).38 In encopresis/soiling children this correlation was notobserved.

Preliminary treatment analysis showed thatchildren with paediatric constipation wereoften helped by laxative treatment, whereas,in contrast, children with encopresis/soilingwere seldom helped, and even becameworse. Review of published work showed thatvarious approaches have been recommendedfor the management of children with enco-presis. Among these have been individual andfamily psychotherapy, behaviour modificationprograms and bowel retaining regimens.39-42Most published studies were either singlecase reports or consist of small groups ofchildren with encopresis/soiling.43 Nolan et alshowed in children with encopresis andevidence of accumulated stool on plainabdominal radiograph, an obvious additionaladvantage of laxative drugs and behaviourmodification to behavioural modificationalone.44 Previously, we showed in a non-randomised study that children with enco-presis and soiling alone were significantlyimproved after biofeedback training.29The use of radio-opaque markers is

important to objectify reports of constipationand or faecal incontinence, which does notdepend on possible inaccurate recall.4547 Usingthe Metcalfmethod an important difference wasfound between the two groups.25 Total as wellas segmental CTT was significantly prolongedin children with paediatric constipation com-pared with those with encopresis/soiling. Thisconfirms that children with encopresis/soiling

have normal bowel movements daily. It isunclear whether children with rapid colonictransit and solitary encopresis without othersymptoms of constipation may be helpedby suppression of intestinal motility ratherthan laxative treatment. Interestingly, colonicinertia, slowing of markers through allcolonic segments, was only found in paediatricconstipation children.48 49No significant differences were found in

OCT in all children studied, suggesting noaetiological role of the small bowel in constipa-tion or encopresis, or both, as describedpreviously.50

Studies of anal sphincter pressures inconstipated children with or without faecalincontinence have been contradictory; maxi-mum anal resting tone has found to beincreased, decreased, or not different fromcontrols.2' 22 51-53 The hypertonicity of theanal canal, as found in the encopresis/soilinggroup only, is uxiexplained. Arhan et alsuggested that hypertonicity of the anal canalcould lead to outlet obstruction.'7 In theencopresis/soiling group, however, no suchcorrelation could be found when rectosigmoidtransit time and maximum anal resting tonewere analysed. Similarly, no such correlationcould be found in patients with paediatricconstipation, despite a significant slowing ofmarkers in the rectosigmoid in this group.Therefore it seems unlikely that anal restingtone is an important factor in the pathophysio-logy of outlet obstruction in children withconstipation or faecal incontinence, or both.The threshold of sensation in children with

paediatric constipation was significantly higherthan in controls and, as stated before, mostlikely the result of faecal impaction.'9-2' 54Surprisingly, the balloon volume needed toprovoke rectal sensation in children withencopresis/soiling was even lower than incontrols, suggesting that patients with enco-presis/soiling are able to perceive normalrectoanal stimuli. Furthermore, none ofthese children had faecal impaction on rectalexamination and most showed normal totalCTT on marker studies. In most of those withencopresis/soiling 'accidents' happened after3.00 pm, whereas in paediatric constipationchildren lost faeces any time during the day.Children with encopresis/soiling commonlytrace the failure to 'no time to go to the toilet'or, 'I could not leave my computer game', or 'Idid sense the urge, but I was just too late', sug-gesting that these children deny or neglecttheir normal and appropriate physiologicalstimuli. Interestingly, many children withencopresis/soiling initially stated an absence ofany sense or urge to defecate.

In the two groups a high percentage ofchildren showed a paradoxal anal response tostraining - that is, contraction rather thanrelaxation of the anal sphincters on defecationattempts. This phenomenon was earlierreported to occur in up to 55% of children andadults with defecation disorders.22 23 55 Thecause of this pelvic floor dyssynergia isunknown. In children with paediatric consti-pation it is suggested that the pain related to

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the defecation of large, firm stools may resultin unconscious contraction of sphincters toavert or stop pain during defecation.22 56Encopresis/soiling patients had, however,except for two children, no history of constipa-tion and none reported the periodic passage oflarge amounts of stools. They had significantlyless pain during defecation and significantlymore normal stools than children withpaediatric constipation, suggesting that analpain is not the only reason for abnormalexpulsion patterns. In addition, within theencopresis/soiling group, rectosigmoid transittime did not differ among the children withnormal or abnormal defecation dynamics,whereas in children with paediatric constipa-tion, abnormal defecation dynamics weresignificantly associated with slowing of markersin the rectosigmoid (p=0 03) compared withthose children with paediatric constipationwho had normal dynamics (data not shown).Loening Baucke showed a decrease inrectosigmoid motility in chronically consti-pated children.57 Thus, in patients withpaediatric constipation abnormal defecationdynamics are related to the slowing of rectosig-moid transit time and decreased rectosigmoidmotility. In contrast, abnormal defecationdynamics in children with encopresis/soilingdid not result in prolonged rectosigmoid ortotal CTT, nor did it lead to abnormal defeca-tion frequencies. This suggests that thesechildren, despite a pathological defecationtechnique, are able to produce complete ornearly complete bowels. As mentioned above,children with encopresis/soiling often be-grudge the time necessary to visit the toilet andconsequently lose some of their bowel contentsduring play. We suggest that after they sensethe urge to defecate they let gotheir first stools and subsequently contracttheir voluntary sphincter muscles firmly. Bydoing this daily, they unconsciously developabnormal defecation dynamics.On the CBCL we observed that children

with paediatric constipation and enco-presis/soiling had a significantly higher inci-dence of behaviour problems than a normativesample of non-referred Dutch children.Loening Baucke et al 58 and Wald et al 22showed similar high percentages for behaviourproblems in children with constipation andencopresis in 500 o and 450 respectively.Currently a prospective study is beingconducted, using the CBCL before and aftertreatment, to analyse whether constipation orencopresis, or both, leads to behaviouralproblems or vice versa.

This study illustrates the importance of theinterpretation of clinical symptoms, the use ofmarker studies, and the value of anorectalmanometry in children with defecation dis-orders. Not all children will present withinfrequent painful defecation associated withabdominal pain and poor appetite. This studyindicates that children reporting encopresiswith normal defecation frequencies, withoutassociated symptoms of constipation, withnormal CTTs and normal threshold of analsensation probably form a distinct entity

among children with defecation disorders. Inour, as yet, limited experience these childrenrespond favourably to behavioural treatmentssuch as biofeedback training.

We are grateful to G W Akkerhuis of the department of childpsychiatry for analysis of the child behaviour checklist.

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