Constipation and faecal incontinence: Viva

Branch 1: Framing the soiling and taking the history

The candidate should first reframe the parents' view that the soiling is deliberate, explaining that most soiling at this age is involuntary overflow around a hard rectal impaction rather than naughtiness. A strong answer takes a structured bowel history: stool frequency, size, and consistency, the presence of withholding behaviour, pain, and blood, and the timing and awareness of the soiling. The candidate should ask about the onset in relation to toilet training and starting kindergarten, both classic triggers for withholding. [1]

The candidate should give equal weight to the psychosocial context, asking how toilet training went, whether toileting has ever been frightening or punitive, and how the family and school respond to the soiling. They should screen for red flags at this point and keep safeguarding in mind for any child with unexplained soiling. Recognising that a previously clean child who soils daily after a school transition most likely has functional constipation with overflow, rather than a behavioural or organic problem, marks a candidate who understands the condition. [2]

Branch 2: Examination, red flags, and investigation

If the examiner asks about examination and tests, the candidate should describe plotting growth, palpating the abdomen for a faecal mass, and inspecting the perianal area, the lower spine for a dimple or hair tuft, and the lower limbs for tone, power, reflexes, and the anal wink. They should state that a digital rectal examination is not routinely needed to diagnose functional constipation. The candidate should be able to make a positive clinical diagnosis when the story is typical and no red flags are present. [1]

A good candidate explains that routine blood tests and an abdominal radiograph are not required and that an abdominal film is unreliable for confirming constipation. They should reserve targeted tests, such as coeliac serology and thyroid function, for atypical features or treatment failure, and reserve referral for rectal biopsy for suspected Hirschsprung disease, flagged by delayed meconium, onset from birth, or distension with failure to thrive. The candidate should retain a low threshold to reassess if the pattern does not fit. [1]

Branch 3: Disimpaction, maintenance, and counselling

If asked about management, the candidate should set out the sequence of disimpaction, maintenance, behavioural support, and long review. For a child with a significant impaction, they should disimpact first with high-dose oral polyethylene glycol, around 1 to 1.5 g/kg/day for three to six days, and be able to justify the oral-first approach from the trial evidence that it matches enemas and is better tolerated. They should warn the family that soiling may worsen briefly during disimpaction. [3]

The candidate should then describe maintenance polyethylene glycol at about 0.4 g/kg/day, titrated to a soft daily stool and continued for months with slow weaning, emphasising that stopping too early is the commonest cause of relapse. They should add behavioural measures, post-meal toilet sitting with foot support and a reward chart for sitting, dietary and fluid advice, and a stimulant laxative if needed. A complete answer finishes by counselling the parents that the soiling is not the child's fault, involving the school, and arranging regular review with clear safety-netting. [1]