Approach
Obtaining a thorough history and physical examination is the crux of diagnosing faecal incontinence. Laboratory and radiological studies may be used on a case-by-case basis to determine the underlying aetiology.[15]
History
History should include the following:
Details of frequency of faecal soiling or diarrhoea
Situation of occurrence - for example, at home or at school, in relation to play activities
Severity of incontinence, as incontinence may be more severe in organic causes
Signs and symptoms of constipation and stool withholding, namely, painful bowel movements, abdominal pain/cramping, and posturing described as tightening of buttocks.[15]
The stooling pattern from birth up to the present, and dietary and medication history, should be noted, along with a history of anorectal, neurological, or spinal abnormalities and surgical interventions.
The physician should also ask about associated bladder dysfunction, enuresis, behavioural concerns, and recent family life events.
Physical examination
A thorough physical examination is crucial to discover any abnormalities, particularly of the neurological, musculoskeletal, and gastrointestinal systems.[15][16][17]
Peri-anal inspection
Inspection of the anus and peri-anal area for evidence of fistulae, displaced/anterior anus, and faecal soiling is important, along with palpation during rectal examination for rectal tone and faecal impaction.
Anorectal examination
Most anorectal and severe spinal deformities are discovered in the newborn period or via foetal ultrasound. Many genetic syndromes can be associated with anorectal malformations, so any potential associated abnormalities should be sought.
Anorectal examination may reveal tears, fissures, anteriorly displaced anus, and distended rectal vault filled with a large amount of firm stool. The presence of a large amount of stool in a dilated rectum is helpful in distinguishing retentive from non-retentive faecal incontinence.
Abdominal examination
Abdominal examination may reveal the presence of a faecal mass and gas in the lower quadrants.
Neurological examination
A thorough neurological examination should be performed in all children with faecal incontinence. Testing of the reflexes, strength, and sensation is necessary, as is inspection of the spine for evidence of dysraphism, such as the presence of a hair tuft or sacral dimple.
Clinical findings
Functional faecal incontinence associated with chronic constipation and severe faecal impaction
The patient has a history of soiling the underwear to various degrees, along with a history of constipation. The soiling often occurs after the child returns home from school.
When the patient experiences a bowel movement in the toilet, it may be described as large and painful. Behaviours to withhold stool may be observed at home, such as tightening of the buttocks to prevent defecation.
The patient may also complain of abdominal pain, decreased appetite, enuresis, and social withdrawal. The child is also unable to feel the urge to defecate, due to the chronically distended rectum.
Functional non-retentive faecal incontinence
The only clinical finding is faecal soiling without evidence of constipation.
The affected patient has normal defecation frequency and stool consistency, and is less likely to complain of abdominal pain or decreased appetite.[10]
Organic faecal incontinence
The patient has an abnormal physical examination finding or history of a physical condition that is associated with the development of faecal incontinence, or may have a history of repair of an anatomical abnormality.
Patients more commonly present with signs and symptoms suggestive of faecal incontinence associated with faecal retention, but may also present with non-retentive faecal incontinence. In general, this category of patients experiences more severe incontinence.
Radiological evaluation
Abdominal x-ray
Abdominal x-ray is indicated to diagnose faecal retention in situations where the patient or parent does not allow the performance of a rectal examination to palpate for stool in the rectum, as well as to show parents that faecal impaction is the actual cause of overflow diarrhoea in their child.[18][19] Although this test is not the most specific study, and may not be recommended by some experts, it is typically easy to obtain in the general paediatric clinic.[20] It can be obtained as baseline evidence of faecal retention, and can be used for subsequent evaluations to note progress or recurrence of faecal retention.[Figure caption and citation for the preceding image starts]: Abdominal x-ray showing severe stool retention in child with faecal soilingFrom the personal collections of Dr Linda S. Nield and Dr Uwe Blecker; used with permission [Citation ends].
Unprepared barium enema
This test can be done as part of a work-up for chronic constipation for evidence of gastrointestinal abnormalities (i.e., Hirschsprung's disease). It is not the definitive test but is more readily available to the primary care doctor and is a good screen for severe and non-responsive constipation. No laxative or enema should be given 72 hours prior to carrying out this study. In Hirschsprung's disease, a transition zone may be noted, which represents the change from the narrowed rectum (aganglionic segment) to the dilated colon proximal to the aganglionic region.[21]
Spinal x-ray or magnetic resonance imaging
These tests can be obtained to diagnose spinal abnormalities associated with faecal incontinence. An abnormal neurological or spinal examination should prompt the ordering of these studies.
Radiopaque marker transit x-ray
This test may be obtained in a tertiary care/motility speciality clinic but is typically unavailable to the primary care clinician. The radiopaque marker transit x-ray is used to look for a slow transit time of the marker passing through and being excreted from the gastrointestinal tract.[22]
Laboratory evaluation
Thyroid studies
Thyroid studies can be done to ensure that faecal retention is not associated with hypothyroidism. Thyroid-stimulating hormone and free thyroxine (T4) should be obtained on a case-by-case basis and are strongly considered if any signs or symptoms of hypothyroidism are present.
Sweat chloride test
This test is done to ensure that faecal impaction is not associated with cystic fibrosis. It should be obtained on a case-by-case basis and strongly considered if any signs or symptoms or family history of cystic fibrosis is present. A sweat chloride test is mandatory in a child who presents with constipation plus rectal prolapse.
Coeliac studies
Coeliac studies (i.e., tissue transglutaminase immunoglobulin A) can be ordered if coeliac disease is suspected, as this disease may present with chronic diarrhoea and constipation. Chronic constipation has been reported as an atypical presentation of coeliac disease.[23]
Further colorectal investigations
Other tests that can be obtained on a case-by-case basis, if indicated by history and physical examination findings, include anorectal manometry, endoscopy, and colonic transit time.[17][24][25][26]
These tests are not ordered or performed by the general paediatrician or primary care provider, but may be ordered and interpreted by a paediatric gastroenterologist. If Hirschsprung's disease has been ruled out, the specialist may consider these tests to look for abnormal rectal sensation or slowed transit time.
Rectal biopsy can be obtained when there is chronic constipation despite compliance with treatment; typically when there is less or no soiling; and when there is a need for recurrent use of enemas to have a bowel movement. It is also done to make a definitive diagnosis of Hirschsprung's disease.[21]
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