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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)
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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
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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
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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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Benninga, Buller, Hevmans, Tytgat, Tamniniau
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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