Constipation in children is a very common problem. It features reduced stool frequency and harder stools.
Faecal impaction refers to when chronic constipation leads to a large build-up of hard stools in the rectum and bowel. The stool blocks the rectum, and the child stops being able to open their bowels. The only stools that can get past the impaction are very loose and tend to be smelly. It can lead to overflow soiling with smelly loose stools.
Causes
Idiopathic constipation, or functional constipation, is when there is no underlying physical cause other than lifestyle and environmental factors. Contributing lifestyle and environmental factors include:
- Reduced fluid intake
- Reduced fibre intake
- Reduced physical activity
- Psychosocial issues (e.g., toilet training problems, stress or abuse)
Key secondary causes of constipation include:
- Hirschsprung’s disease
- Cystic fibrosis (particularly meconium ileus)
- Hypothyroidism
- Medications (e.g., antihistamines or opiates)
Presentation
The frequency of bowel movements varies between individuals, particularly in breast-fed babies. Someone opening their bowels daily may be constipated, whereas someone else opening their bowels three times a week may not, depending on what is normal for them.
Presenting features of constipation include:
- Reduce frequency of bowel movements (e.g., less than three times per week)
- Hard or large stools that are difficult to pass
- Rabbit-dropping stools (small round stools)
- Straining
- Painful passage of stools
- Overflow soiling (incontinence of particularly smelly loose stools)
- Rectal bleeding associated with hard stools
- Abdominal pain
- Holding an abnormal posture, referred to as retentive posturing
- Hard stools may be palpable on abdominal examination
Inspection of the anus is required to look for abnormalities such as infection, fissures, fistulas or bruising. Digital rectal examination is not routinely performed in children.
Perianal group A streptococcal infection causes pain and erythema (redness) at the anus and surrounding skin. This can cause constipation. Swabs should be taken. It is treated with antibiotics (e.g., phenoxymethylpenicillin).
Red Flags
Red flags that may indicate a serious underlying condition and require prompt referral and investigations include:
- Not passing meconium within 48 hours of birth (cystic fibrosis or Hirschsprung’s disease)
- Neurological signs or symptoms, particularly in the lower limbs (cerebral palsy or spinal cord lesion)
- Vomiting (intestinal obstruction or Hirschsprung’s disease)
- Ribbon stool (anal stenosis)
- Abnormal anus (infection, stenosis, inflammatory bowel disease or sexual abuse)
- Abnormal lower back or buttocks (spina bifida, spinal cord lesion or sacral agenesis)
- Failure to thrive (coeliac disease, hypothyroidism, cystic fibrosis or safeguarding issues)
- Acute severe abdominal pain and bloating (obstruction or intussusception)
Complications
- Pain
- Anal fissures
- Haemorrhoids
- Overflow and soiling
- Psychosocial morbidity
Management
Idiopathic constipation can be diagnosed without any further investigations, provided red flags are excluded.
Adequate explanation and appropriate reassurance are essential for the child, parents, and carers. Treatment can take a long time (months) and requires the family to be in agreement.
Health visitors and nurse-led bowel services may be available for support.
Behavioural and lifestyle interventions include:
- Sufficient fluid intake
- Sufficient fibre intake
- Sufficient physical activity
- Regular attempts to open the bowel (e.g., after each meal)
- Bowel movement chart
- Encouragement systems (e.g., star charts)
Initial treatment for constipation in children involves:
- Macrogol laxatives (e.g., Movicol paediatric) first-line
- Stimulate laxatives (e.g., Senna) second-line
Paediatric macrogol laxatives contain polyethylene glycol (macrogol) and electrolytes. They are osmotic laxatives, and they work by drawing water into the stool, making it softer and easier to pass. The dose is escalated as required until regular soft stools are achieved. Lactulose is a common alternative osmotic laxative.
For faecal impaction, the dose is escalated every few days, up to a maximum of 8-12 sachets daily, depending on their age (specific regimes are found in the BNF).
Maintenance laxatives (typically with half the dose required for disimpaction) may be needed for weeks or months to establish a healthy bowel routine.
Last updated February 2025
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