Chronic constipation and faecal incontinence commonly present to general practitioners. They account for 5% of paediatric outpatients referrals, and make up 35% of the workload of a paediatric gastroenterologist. Up to 10% of children have experienced constipation. Constipation with faecal incontinence soiling occurs in 4% of pre-school children and 2% of school children. 

Normal stool pattern varies with age. A newborn may stool four or more times per day, depending on whether he/she is breast or bottle fed. By four months of age, on average, stool frequency reduces to two stools per day, and to one per day by four years. 

Functional constipation (no organic cause) can be considered a ‘learned phenomenon’. If a child experiences a painful bowel movement, they may voluntarily withhold defecation. Stool passage is delayed by voluntary contraction of the levator ani and external anal sphincter muscles. Hardened stool, which is more difficult to pass, accumulates in the rectum; thus the cycle of painful defecation and withholding continues. The lower colon gradually distends with accumulated stool and the urge to defecate becomes irregular due to decreased rectal sensation. When the rectum is sufficiently distended, softer stool leaks around the bulk of hard stool. 

The passage of soft stool is not sensed by the child until soiling has actually occurred. Recognised triggers that allow the constipation cycle to continue include: difficulties with toilet training; school or home stresses; inter-current illnesses; avoidance of public toilets; and/or hectic lifestyles. Once initiated, the constipation cycle is difficult to break. However, with effective diagnosis and proper treatment, the condition can be successfully managed in the primary care setting.

Anal fissures are commonly associated with constipation. Often the passage of a hard stool can cause a linear tear in the distal anal canal. There may be a history of painful defecation associated with bright red blood either on the stool, in the nappy or on toilet paper. On examination, a small skin tag or ‘sentinel pile’ may be observed at the 12 or six o’clock position. Provided the stool is kept soft, anal fissures usually heal spontaneously. 

Some 90-95% of constipation is functional. In approximately 5% of cases an organic cause can be found. The frequency is not well defined, however in the neonatal period an organic cause is more likely. See Table 1.

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Investigations

In what circumstances should a digital rectal examination be performed?

In children with functional constipation, digital rectal examinations are often unnecessary. However in cases where the diagnosis is unclear, a digital rectal examination can help distinguish functional from organic constipation and can alter the course of therapy. As the examination is often poorly tolerated by children, it should be performed only once. It should only be undertaken by physicians who are competent in their ability to interpret the clinical findings. Therefore, in most cases, the examination will be performed by the specialist to which the child has been referred.

Do plain films of the abdomen aid in the diagnosis of constipation?

Plain film of the abdomen may show a rectal faecal mass but there is little correlation between the clinical picture and radiological diagnosis. Routine radiography is therefore not routinely recommended. However, for those patients with a history of infrequent bowel movements but no objective findings of constipation, an evaluation of colonic transit time with radiopaque markers may be useful in selected cases. 

Is urinalysis required?

Urinalysis must be carried out to exclude urinary tract infection. Constipation with a dilated rectum causes the same pattern of voiding dysfunction as that encountered in children with persistence of an unstable bladder. Effective treatment of the constipation results in normalisation of bladder function and cessation of urinary tract infections.

Should stool routinely be tested for occult blood?

It is recommended that a test for occult blood in the stool be performed in all infants with constipation, as well as in any child who also has abdominal pain, failure to thrive, intermittent diarrhoea, or a family history of colon cancer or colonic polyps.

When is a rectal biopsy indicated?

Rectal biopsy is rarely required unless there are symptoms of intractable constipation from birth with associated abdominal distension and a delayed passage of meconium. Rectal biopsy is done to exclude Hirschsprung’s disease – a rare condition occurring in one in 7,000 births. 

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Management

Four-step approach to management of functional chronic constipation

• Clarifying and pitfall avoidance strategies
• Education (including dietary modification and bowel training)
• Disimpaction
• Maintenance

Step 1 – Clarifying and pitfall avoidance strategy

Parent

a) Symptom recall of constipation 

PITFALL: If the parent asks the child, during the consultation, how often they pass a bowel movement, the information is likely to be unreliable. Children usually do not keep track of this type of information. Get the parents to log the bowel movement frequency  instead. The Bristol stool chart is a useful aid to clarify the stool type. 

b) Diarrhoea in the child with constipation

RATIONALE: Parent will assume that diarrhoea occurring in a child with constipation is related to an episode of gastroenteritis. It often reflects over flow of the constipated stool.

c) This child who soils his underwear 

RATIONALE: This is an indicator of constipation with overflow.

d) The parental response to soiling 

RATIONALE: Parents are often very surprised that their child passes some stool in their underwear and does not recognise that the event has occurred especially when the parent has noticed the smell of faeces. Often their first response, prior to seeking a medical opinion, is disbelief, then they may become annoyed or believe that the child is soiling to get attention. 

e) Stool avoidance practices 

RATIONALE: In all children with constipation, parents should be questioned regarding withholding manoeuvres. Parents sometimes see these as attempts at defecating but they rarely take place in the bathroom, more commonly the child hides.

f) Constipation and the presence of psychological problems

PITFALL: Effective treatment of constipation should be the first recommendation to parents of a child with constipation. If effectively treated, it is uncommon to find underlying psychological problems.

g) Dependency on laxatives 

RATIONALE: Parents are often concerned that their child will become dependent on laxatives. There is no evidence to support this view.

Doctor

h) If parents have used suppositories define the treatment response

PITFALL: The passage of thin, ribbon-like stools in response to a suppository should prompt consideration of short segment Hirschsprung’s disease.

i) The non-responding child

RATIONALE: If the child does not respond to therapy once adherence has been assured, rethink the diagnosis of constipation and seek secondary causes such as coeliac disease, hypothyroidism or polyuric states.

j) Medication usage by the parent

PITFALL: Transit studies are useful in the child who is not responding to medication where there are concerns of medication non-administration.

k) Weight gain and poorly controlled constipation 

RATIONALE: Check the diet for ‘junk foods’ and strongly encourage a reduction in consumption.

Step 2 – Education including dietary modification and bowel  training

Dietary modification 

In order to encourage the production of soft bulky stool, children need to have adequate amounts of fibre in their diet. It has been shown that the Irish paediatric population does not take adequate fibre. High-fibre intake with regular meals should be encouraged along with six to eight cups of water-based fluid per day. For children older than two years of age, the amount of fibre that they should be eating daily can be calculated by taking the child’s age in years and adding five. This equates to the amount of fibre in grams the child should consume in grams. 

Foods high in fibre that should be recommended include: 

• Breakfast : All Bran, Bran Flakes, Sultana Bran, Weetabix, Shreddies, muesli and porridge oats
• Lunch: Brown, wholemeal and granary bread
• Dinner: Wholegrain pasta and rice
• Vegetables: Sweet corn and peas
• Legumes: Baked beans, kidney beans and lentils
• Snacks: Dried apricots, prunes, raisins and figs
• Fruit: Blackberries, raspberries, strawberries, passion and kiwi fruit.

Bowel fitness training

Bowel fitness training is essential to re-establish normal bowel habits. However, regular ‘sits’ on the toilet can pose compliance issues. Star charts can provide a useful means of improving compliance. Bowel fitness training works by exploiting the gastro-colic reflex, therefore the best time for children to sit on the toilet is after meals, particularly breakfast. A regular programme of three five- to 10-minute sits per day on the toilet after each home meal is recommended. It is equally important to ensure that children are in a comfortable position when sitting on the toilet. Therefore, children should have a foot stool to ensure the hips can be fully flexed during sits.

The success or failure of the whole treatment programme rests with the child’s adherence to this sitting regime. Bowel fitness training needs to continue for at least six months until the normal sensory feedback in the lower colon has returned. 

Step 3 – Disimpaction

Disimpaction can be carried out through the oral or rectal routes, with oral being the preferred route. Polyethylene glycol 3350 with electrolytes or Movicol should be used as first-line treatment for disimpaction. An escalating dose regime should be used. If there is no response to treatment after two weeks, a stimulant or osmotic laxative (eg. lactulose) can be added. 

In order to ensure compliance, it is important that both children and parents are informed that disimpaction treatment can cause abdominal pain and discomfort. The regime should be reviewed once disimpaction has occurred. This is usually indicated by the passage of a large stool. Movicol dosage should then be reduced by two sachets per day until soft stool is being passed. This dose of Movicol can then be used as maintenance dose.

Step 4 – Maintenance

Once disimpacted, maintenance therapy aims to allow the muscles and nerves of the lower bowel to recover by promoting regular toileting and preventing further impaction. Movicol is a safe and effective maintenance treatment for constipation in children to achieve this goal. 

The dose should be adjusted according to stool consistency and frequency. For children aged one to six years, the usual dosage is one sachet daily, however doses up to a maximum of four sachets daily can be used. For children six to 12 years, the usual dosage is two sachets daily, however up to a maximum of four sachets daily can be used. For children older than 12 years, Movicol adult preparation can be used. The usual dosage is one to three sachets daily. 

In order to ensure compliance and prevent impaction, it is important to explain to parents that their child may be on this treatment for a prolonged period of time and that the medication should not be stopped abruptly. 

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For those children who cannot tolerate Movicol, there are a number of alternative treatment options available, including osmotic and stimulant laxatives.  

Long-term use of stimulant laxatives is not recommended. Lactulose is licensed for use in children from four weeks of age. Dosage should be adjusted according to stool consistency and frequency, however the usual dose for children is:

• One month to one year: 2.5ml BD
• One to five years: 2.5-5ml BD
• Five to 18 years: 5-20ml BD

Follow-Up

• Children require regular primary care or outpatient visits to monitor and adjust their medications
• Medication should be continued until a regular bowel pattern is established
• In order to ensure that a relapse of constipation does not occur, the child should continue to be monitored when stopping or reducing medication
• In those children who continue to soil, non-compliance with the sitting regime is the most important contributory factor
• In extreme cases, a short admission to hospital may be required.

Summary 

• Constipation is common in children
• The majority of children who soil have chronic constipation
• Very few children require investigations 
• Stool softening with Movicol Paediatric or lactulose forms the basis of medical treatment
• Regular sits for five to 10 minutes after meals is essential for resolution
• The vast majority of cases can be managed in primary care.