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Assessment and treatment of constipation

Jayne Richardson
RN
Clinical Nurse Specialist for Continence Care
Scarborough and North East Yorkshire NHS Trust

The normal frequency of emptying the bowels varies from three times a day to three times a week, although some people may go a whole week without experiencing discomfort or harmful effects. A good definition of constipation is: "The passage of hard stools less frequently than the patient's own normal pattern."(1) However, the accepted international definition requires the presence of two of the following symptoms for at least 12 months when not taking laxatives:(2)

  • Straining at least 25% of the time.
  • Feeling of incomplete evacuation at least 25% of the time.
  • Hard or pellet stools at least 25% of the time.
  • Two or fewer bowel movements per week.

A person is likely to be constipated if they have:

  • Waste matter that is too hard to pass easily.
  • Bowel movements that are so infrequent that pain and discomfort may result.
  • A sensation of incomplete evacuation.
  • Less frequent bowel movements than are normal for that individual.

A survey of district nurse time spent dealing with constipation showed constipation costs the NHS as much as £810,000 per year in nurse time alone.(3) Arising from this, care pathways have been developed to aid assessment.(4)
Some laxatives are already available in the Nurse Prescribers Formulary, but the planned extension of nurse prescribing will mean more nurses will be able to prescribe for a broader range of medical conditions.
A significant proportion of laxatives are prescribed for the elderly. The Department of Health, in the National Service Framework for Older People, recommends reviews of medications every six months to a year.(5) This should promote the appropriate prescribing of laxatives and reduce health costs.

The causes of constipation
Primary constipation has no underlying causative illness and is associated with lifestyle factors such as:

  • Lack of fibre in the diet.
  • Insufficient fluid intake.
  • Inadequate exercise.
  • Environmental or psychological reasons.

Secondary constipation has an underlying cause:

  • Latrogenic (eg, opiates, diuretics, antidepressants).
  • Endocrine (eg, hypothyroidism, diabetes).
  • Neurological (eg, Parkinson's disease, stroke).
  • Psychiatric (eg, depression, anxiety, dementia).

Constipation is more common in women (10%) than men (2%) - regular straining is experienced by 52% of women and 39% of men. Prevalence rapidly increases in those aged over 65.

Assessment and treatment
A full history should be taken, which should include:

  • Bowel habits.
  • Stool type (use the Bristol Stool Scale).
  • Lifestyle.
  • Environmental factors.
  • Medical history.
  • Medications.
  • A physical examination.

Once constipation has been identified, advise on how to promote regular opening of the bowels without undue straining or discomfort. Initially medication may be needed to achieve this, but for simple constipation a change in dietary habits, increased fluid intake and improved mobility may be all that is needed.
Dietary and lifestyle advice should be the firstline approach to treatment. Patients should be encouraged to increase their dietary fibre and fluids, as this will improve the long-term outcome of their constipation.(6) The fluids increased should not include alcohol, tea and coffee, which themselves are diuretics.
A high-fibre diet may be a more expensive option and many elderly consider it unpalatable, especially if their appetite is reduced. A high-fibre diet should not be introduced to patients with megacolon/rectum or hypotonic colon, as faecal bulk will not trigger ­peristalsis or defecation, and their condition will be made worse.
People with constipation should be urged to respond to the urge to defecate and make use of the gastrocolic reflex that occurs after meals. More exercise, regular meals and a regular routine for bowel movement must be encouraged. The long-term benefits of the initial treatment will re-educate the patient and the bowel. This lifestyle advice should also be implemented with any pharmacological therapy.

Pharmacological treatment
For people who do not respond to diet and lifestyle changes or who are in discomfort or pain, pharmacological treatment may be required (see Table 1). Before laxatives are prescribed, consider the following:

  • Age, mobility and existing medical conditions.
  • Any contraindications.
  • The degree of constipation.
  • The patient's preferred choice of drug or ­administration route.
  • Any prior self-medication.
  • Cost.
  • The onset of action required.

[[NIP06_table1_44]]

Acute constipation needs a quick solution, usually a stimulant laxative, which has an effect in 8-12 hours. Specific laxatives are required before operations.
A longer-term solution is required for chronic constipation. If lifestyle advice and diet are not effective, bulk forming agents are usually the preferred treatment.
The NHS Centre for Reviews and Dissemination drew the following conclusions:

  • Laxative treatments are associated with increased bowel frequency and improvement of symptoms of constipation.
  • Bulk (fibre-based) laxatives and osmotic laxatives are associated with an increase in frequency and improvement in stool consistency and symptoms.
  • Little evidence is available on the comparative effectiveness of bulk and nonbulk laxatives.
  • There is no good evidence that laxatives prevent constipation in older people.
  • A stepped approach to treatment would seem ­justified, involving initial treatment with cheaper laxatives before proceeding to more expensive alternatives.
  • There is a need for a large comparative trial of different strategies for the management of ­constipation in adults, including comparison of the effectiveness of different classes of laxatives.

References

  1. British Medical Association and the Royal Pharmaceutical Society of Great Britain. British National Formulary 39.
  2. Drossman DA, et al. Identification of sub-groups of functional gastro-intestinal disorders. Gastroenterol Int 1990;3:159-72.
  3. Royal College of Nursing. The cost of constipation. London: RCN; 1999.
  4. Bayliss V, Cherry M, Locke R, Salter L. Pathways for continence care: ­development of the pathways. Br J Nurs 2000;9:1165-72.
  5. Department of Health. NSF for Older People. London: The Stationery Office; 2001.
  6. Giacosa A. The effects of fibre on constipation and functional bowel disease. International Congress and Symposium Series. 1999;236:51-7.
  7. The management of constipation. Medicines Resource Centre Bulletin 1999;10(9):33-6.
  8. NHS Centre for Reviews and Dissemination. Effectiveness of laxatives in adults. York: University of York; 2001.

Resources
RCN Continence Care Forum
Royal College of Nursing
20 Cavendish Square
London W1G ORN
T:020 7240 9333
ASBAH
42 Park Road
Peterborough
PE12UQ
Enuresis Resource & Information Centre (ERIC)
T:0117 960 3060   W:www.eric.org.uk
The Continence Foundation
307 Hatton Square
16 Baldwin Gardens
London EC1N 7RJ
T:020 7831 9831 W:www.continence-foundation.org.uk
The Association for Continence Advice
Winchester House
Cranmer Road
London SW9 6EJ
T:020 7820 8113
Digestive Disorders Foundation
W:www.digestivedisorders.org.uk