Constipation and faecal incontinence: SAQ

This boy has functional constipation with retentive faecal incontinence. The apparent loose leaking is overflow of liquid stool around a hard rectal impaction, confirmed by the once-weekly enormous stools, the withholding posture, and the palpable faecal mass, with a normal examination and no red flags allowing a positive diagnosis. [1]

Question 1 (10 marks)

Explain why this child soils, how you would confirm the diagnosis, and which features would make you consider an organic cause. [1]

The soiling is retentive faecal incontinence, an involuntary overflow of soft stool that tracks around a hard impaction and leaks through an anus the child can no longer keep closed. Chronic withholding has stretched the rectum into a low-tone megarectum that no longer signals fullness, so the child cannot feel the leakage and is not being naughty. The diagnosis of functional constipation is clinical, resting on the typical history of infrequent large stools and withholding, the palpable faecal mass, and a normal examination, and it can be made positively using the Rome IV criteria without routine blood tests or an abdominal radiograph. I would actively screen for red flags that point to an organic cause: constipation or delayed meconium from the first weeks of life, ribbon stools, abdominal distension with bilious vomiting, growth faltering, an abnormal anus or sacral dimple, and abnormal lower limb neurology or anal wink, all of which would prompt consideration of Hirschsprung disease, a spinal lesion, or another organic diagnosis. I would also keep safeguarding in mind for any child with unexplained soiling. [1]

Question 2 (10 marks)

Outline your management plan, including specific disimpaction and maintenance treatment, and how you would counsel the family. [3]

I would begin with a clear, non-punitive explanation that the soiling is involuntary overflow around trapped stool and that treatment takes months. Because he has a significant impaction, I would disimpact first with high-dose oral polyethylene glycol, around 1 to 1.5 g/kg/day for three to six days, which a randomised trial showed is as effective as enemas and better tolerated, warning the family that soiling may briefly worsen as the blockage clears. I would then start maintenance polyethylene glycol at about 0.4 g/kg/day, titrated to a soft painless daily stool, and continue it for at least two months and until he has been symptom-free for a further month before slow weaning, because stopping too early is the commonest cause of relapse. Alongside the laxative I would add behavioural measures: unhurried toilet sitting for a few minutes after meals to use the gastrocolic reflex, proper foot support, and a reward chart for sitting rather than for producing stool, together with adequate fluid, a balanced diet, and activity. I would add a stimulant laxative such as senna if the osmotic laxative alone were insufficient, arrange regular review, involve the school in a supportive plan, and safety-net clearly. [2]