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PatientPlus articles are written for doctors and so the language can be technical. However, some people find that they add depth to the articles found in the other sections of this website which are written for non-medical people.

Constipation

What is constipation?

Constipation is a symptom not a diagnosis and means different things to different people. Always ask patients exactly what they mean by the term constipation. There are various formal (and different) definitions of constipation. It is defined as defecation that is unsatisfactory because of infrequent stools (<3 times weekly), difficult stool passage (with straining or discomfort), or seemingly incomplete defecation. Stools are often dry and hard, and may be abnormally large or abnormally small.1

Patients may mean that:

  • Faeces are too hard
  • They do not defecate often enough for 'inner cleanliness'
  • Defecation hurts
  • They have diarrhoea.
Causes of constipation

A careful history helps to determine the possible cause. Ask about frequency, nature and consistency of the stool. Is there blood or mucus in/on the stools? Is there diarrhoea alternating with constipation? Has there been a recent change in bowel habit? Ask about diet and drugs.

Rectal examination is essential.

Causes of constipation
Common Causes Low fibre diet
Inadequate fluid intake or dehydration
Immobility (or lack of exercise)
Irritable bowel syndrome
Old age
Post-operative pain
Hospital environment (lack of privacy, having to use a bed pan)
Anorectal Disease Anal fissure
Anal stricture (See Around the anus)
Rectal prolapse
Intestinal Obstruction Strictures (eg Crohn's disease)
Colorectal carcinoma
Pelvic mass (eg fetus, fibroids)
Diverticulosis (rectal bleeding is a commoner presentation)
Congenital abnormalities
Pseudo-obstruction
Metabolic / endocrine Hypothyroidism
Hypercalcaemia
Hypokalaemia
Porphyria
Lead poisoning
Drugs Opiate analgesics (eg morphine, codeine)
Anticholinergics (tricyclics, phenothiazines)
Iron
Neuromuscular Spinal or pelvic nerve injury
Aganglionosis (Chagas' disease, Hirschsprung's Disease)
Systemic sclerosis
Diabetic neuropathy
Other Causes Chronic laxative abuse (rare - diarrhoea is commoner)
Idiopathic slow transit
Idiopathic megarectum/colon
Investigations
  • Most constipation does not need investigation, especially young, mildly affected patients.
  • Indications for investigation include:
    • Age >40yrs
    • Recent change in bowel habit
    • Associated symptoms (weight loss, rectal bleeding, mucus discharge, or tenesmus)
  • Possible investigations include:
    • Blood tests: FBC , U&E , Ca2+, TFTs.
    • Sigmoidoscopy and biopsy of abnormal and normal mucosa.
    • Barium enema if suspected colorectal malignancy.
    • Special investigations (eg transit studies; anorectal physiology) are occasionally indicated.
Management
  • Treat the cause
  • Mobilise the patient
  • Consider drugs only if above measures fail
  • Try to use drugs for short durations only

Drug therapy

Drugs for constipation
Bulk producers:
  • Increase faecal mass, which stimulates peristalsis
  • They must be taken with plenty of fluid
  • Contraindications: difficulty in swallowing; intestinal obstruction; colonic atony; faecal impaction.
 Examples:
Stool softeners:
  • Side effects can include: anal seepage, lipoid pneumonia, malabsorption of fat-soluble vitamins.
  • Arachis oil enemas lubricate and soften impacted faeces.
  • Liquid paraffin should not be used for a prolonged period.
Stimulants:
  • Increase intestinal motility and should not be used in intestinal obstruction.
  • Prolonged use should be avoided as it may cause colonic atony and hypokalemia (but there are no good, longterm follow up studies).[R]
  • Pure stimulant laxatives are bisacodyl tablets (5-10mg at night) or suppositories (10mg in the mornings) and senna (2-4 tablets at night).
  • Docusate sodium and danthron (dantron) have stimulant and softening actions; however danthron is associated with colonic and liver tumours in animals - so reserve its use for the very elderly and terminally ill.
  • Glycerol suppositories act as a rectal stimulant.
  • Sodium picosulfate is useful for rapid bowel evacuation prior to procedures.
Osmotic agents:
  • Retain fluid in the bowel.
Enemas and suppositories- useful additional treatment
  • Sodium phosphate enemas and Glycerine suppositories may be useful.
  • Sodium salts (eg Microlette® and Micralax® enemas) should be avoided as they may cause sodium and water retention.
  • Phosphate enemas are useful for rapid bowel evacuation prior to procedures.
  • Excessive use of soapy tap water enemas may lead to water intoxication.
Cost
  • Cheap: Senna, Bran, Co-danthrusate, Bisacodyl.
  • Moderate: Magnesium hydroxide, Methylcellulose, Ispaghula granules, Sterculia.
  • Expensive: Lactulose.

Constipation in children

This is covered in the article on Constipation in Children.

Document references
  1. Constipation, Clinical Knowledge Summaries (January 2008)
Internet and further reading Acknowledgements EMIS is grateful to Dr Richard Draper for writing this article. The final copy has passed scrutiny by the independent Mentor GP reviewing team. ©EMIS 2008.
DocID: 2001
Document Version: 20
DocRef: bgp841
Last Updated: 18 Apr 2008
Review Date: 18 Apr 2010




















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PS - Health and Poverty

Perhaps the biggest cause of ill health in the world is poverty. Help to Make Poverty History. For example, why not lend some of your money to disadvantaged communities to enable them to trade their way out of poverty through schemes such as Shared Interest.

See also MAKEPOVERTYHISTORY North East for details and links to campaigns against poverty.

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