Constipation week – Day 4: Evidence on Tough Topics

Cite this article as:
Angela Clarke. Constipation week – Day 4: Evidence on Tough Topics, Don't Forget the Bubbles, 2014. Available at:

Bottom line: (pun definitely intended!)

  • A PR examination should only be undertaken by a doctor competent to interpret features of anatomical abnormalities or Hirschsprung’s disease e.g. paediatric surgeons
  • TFTs and coeliac screen should only be ordered by specialists in patients with intractable constipation
  • Abdominal xrays and abdominal ultrasounds are not recommended to aid diagnosis of constipation
  • Dietary interventions alone are not recommended but should be used in conjunction with a laxative
  • According to evidence, PEG 3350 (Movicol) should be the oral laxative of choice
  • Maintenance regimes should be continued for several weeks to months
  • Routine use of enemas is not recommended

See our other Constipation Week posts

Do I order TFTs and coeliac screen?

Thyroid function testing and coeliac screening should only be ordered by a specialist service as part of the investigation of intractable constipation when atypical presentations of these diseases are considered. There are no published studies stating the prevalence of coeliac disease and hypothyroidism in children with idiopathic constipation (Reuchlin-Vroklage et al, 2005).

Should I get an abdominal x-ray to confirm my diagnosis?

Evidence shows that abdominal x-rays play little role in confirming or refuting the diagnosis of constipation as there is poor diagnostic accuracy and reproducibility (Reuchlin-Vroklage et al, 2005). It is important to remember that the average radiation dose of an abdominal x-ray is 0.7mSv, that’s 7 times higher than a chest x-ray. That is relatively high compared to the background yearly exposure of approximately 3mSv (Mettler et al, 2008).

What about an abdominal ultrasound?

Abdominal ultrasounds have shown that children with idiopathic constipation have a larger rectal diameter than those without constipation. However, they don’t give any extra information than what is obtained through thorough history taking and examination and are therefore not routinely recommended.

Which laxative do I choose?

There are a series of case series and randomized control trials that show treatment with PEG 3350 was effective in causing disimpaction of children with constipation.  The studies show that higher doses are more effective than smaller doses and that PEG 3350 is more effective than stool softeners and enemas (Youssef et al, Tolia et al, Guest et al ). There is currently no evidence of the effectiveness of stimulant laxatives in treating disimpaction.

The NICE ‘Constipation in children and young people’ guidelines suggest the following management for children over 1 year of age:

  1. Rule out ‘Red flags’.
  2. Assess for impaction – i.e. overflow soiling and/or faecal mass palpable abdominally. Start maintenance therapy for those not faecally impacted, treat for disimpaction if faecally impacted.
  3. Treat for disimpaction or commence maintenance therapy:
    • 1st line – Macrogol PEG 3350  – escalating dose regime for disimpaction or adjusted according to response in maintenance regime.
    • 2nd line – (2 weeks later) Add a stimulant laxative (e.g. sodium picosulfate,  bisacodyl, senna,)
    • 3rd line – Substitute a stimulant laxative singly or in combination with an osmotic laxative (lactulose) if Macrogol PEG 3350 not tolerated.
    • 4th line – Enema (stimulant laxative: Microlax or Bisacodyl)
    • 5th line – Manual evacuation under anaesthetic.
  4. Continue maintenance regime for several weeks to months.
  5. Medications not to be stopped abruptly but to be weaned over a period of months.

Dosage guides are provided in the guideline –



Reuchlin-Vroklage LM, et al. Diagnostic value of abdominal radiography in constipated children: a systematic review. Archives of Pediatrics and Adolescent Medicine. 2005;159(7):671-8.

Mettler FA, et al.  Effective Doses in radiology and Diagnostic Nuclear Medicine: A Catalog. Radiology. 2008 Jul ;248(1):254-63.

Youssef NN, et al. Dose response of PEG 3350 for the treatment of childhood fecal impaction. Journal of Pediatrics. 2002;141(3):410-4.

Tolia V, et al. A prospective randomized study with mineral oil and oral lavage solution for treatment of faecal impaction in children.  Alimentary Pharmacology and Therapeutics. 1993;7(5):523-9.

Guest JF, et al. Clinical and economic impact of using macrogol 3350 plus electrolytes in an outpatient setting compared to enemas and suppositories and manual evacuation to treat paediatric faecal impaction based on actual clinical practice in England and Wales. Current Medical Research and Opinion. 2007;23(9):2213-25.

Candy DC, Edwards D, Geraint M. Treatment of faecal impaction with polyethelene glycol plus electrolytes (PGE + E) followed by a double-blind comparison of PEG + E versus lactulose as maintenance therapy. Journal of Pediatric Gastroenterology and Nutrition. 2006;43(1):65-70.

Pashankar DS and Bishop WP. Efficacy and optimal dose of daily polyethylene glycol 3350 for treatment of constipation and encopresis in children. Journal of Pediatrics. 2001;139(3):428-32.

Constipation week – Day 3 – Treatment

Cite this article as:
Tessa Davis. Constipation week – Day 3 – Treatment, Don't Forget the Bubbles, 2014. Available at:

Emptying the bowels

There are two essential components – stimulants and softeners. In the past we used enemas and stool softeners. Enemas can be effective, but often you are just unblocking at the bottom end which doesn’t deal with the whole problem.

When discussing the effects of a treatment with families, it is useful to be able to recognise the difference between old poo and new poo. Old poo will be dark, hard, and smelly. New poo will be paler, softer, and less smelly. The aim of treatment is to get rid of all the old poo.

Once the bowel is empty and stays empty, it will return to a normal shape and laxity.

 See our other Constipation Week posts


Stimulants can be used to help get things moving – these include laxatives, senecot, prune juice, dulcolax tablets (crushed and sprinkled). Senna or bisacodyl directly stimulate the nerve endings in the colon to increase intestinal motility. These are granules which can be eaten plain or mixed with water, milk or food. Cramps and abdominal pain are common. There is some suggestion of it leading to lazy bowel with long-term use.

Often stimulants will be used temporarily to help empty the bowel and will then be weaned.

With Dulcolax, a typical dose would be: 1 per day for a 5 year old; 2 per day for a 10 year old. It is usually given at 3-4pm and works within 3-4 hours. So the child usually opens their bowels that evening or the following morning.



Osmolax is one of the mainstays of constipation treatment. It simply adds water to the poo which makes it softer and easier to pass. It does not have an effect elsewhere in the body, simply a local effect on the stool. Therefore, it is safe to keep on taking it indefinitely – and some people do.

The best management is to take the same amount every day. Taking it on alternate days, or even just some days, won’t help – the aim is to soften the poo and so that needs to be done regularly. With children, the usual dose is 1-3 scoops per day (although smaller amounts can be used).

Osmolax is given in scoops, and children seem not to object to the taste too much. When weaning Osmolax, wean down the number of scoops per day. Movicol was the precursor to Osmolax. It does the same job, but it contains electrolytes and so children tend not to like the taste as much. Both of these are types of PEG 3350.

What can we give to babies?

In children under 12 months old, just use lactulose or coloxyl drops. Coloxyl does more than just adding water to the stools – it does get absorbed by the body so it is a drug (unlike Osmolax). Both lactulose and coloxyl are, however, fairly benign. In babies, the cause of constipation can often be due to packing in formula into the bottles (even a 20-30% increase in formula can cause constipation). In infants <12 months old, there is no good evidence that a high fibre diet can treat or prevent constipation. 

How do we know when we succeed?

Usually treatment should continue for at least three months to treat reservoir constipation (although can be longer). Once the child is producing normal diameter stools that are not watery then things are returning to a good place. It’s true that everyone is different. In general, aim for bowels opening every day (at least every two days). Stool should be soft and easy to pass.

There is no rush to wean the meds once this is achieved, and often the child also has to unlearn the fear they have about going to the toilet.