Constipation

Introduction to Constipation

Constipation is a clinical condition in which a person has uncomfortable or infrequent bowel movements and/or passage of hard stools.
Generally, a person is considered to be constipated when bowel movements result in passage of small amounts of hard, dry stool, usually fewer than three times a week.

Causes of Constipation

  1. Inadequate fibre in diet (simple constipation)
  2. Drugs e.g. tricyclic antidepressants, narcotic analgesics, (atropine, codeine, morphine, disopyramide) etc
  3. Diseases of the anus, rectum and colon e.g. fissures, haemorrhoids, cancer
  4. Irritable bowel syndrome
  5. Metabolic diseases e.g. hypothyroidism, hypercalcaemia
  6. Ignoring the urge to defaecate e.g. due to immobility
  7. Lazy bowel from chronic laxative use including ‘herbal’ preparations
  8. Lack of exercise
  9. Dehydration and starvation (particularly in children)

Other Causes

  • Gastrointestinal obstruction
  • Anal fissure and other painful perianal lesions
  • Carcinoma of the rectum and sigmoid colon
  • Foreign body in the gut
  • Pelvic mass e.g. fibroid, foetus
  • Aganglionic and acquired megacolon
  • Pseudo-bowel obstruction (Ogilvie syndrome) following immobility from any cause

Symptoms of Constipation

  • Dry, hard and/or lumpy stools
  • Abdominal bloating
  • Excessive flatulence.
  • Fewer than three bowel movements a week.
  • Difficult or painful defecation
  • A possible stomach ache or cramps.
  • A feeling of incomplete bowels emptying after a movement.

Complications of Constipation

  • Megacolon
  • Anal fissures/tears
  • Haemorrhoids
  • Rectal bleeding

Diagnosis

  • Stool examination including microscopy.
  • Proctoscopy/sigmoidoscopy.
  • Barium enema
  • Serum hormonal levels e.g. thyroxine, triiodotyronine, thyroid stimulating hormone to exclude hypothyroidism

Treatment objectives of Constipation

  • Identify and eliminate cause(s)
  • Evacuate hard faecal matter

Where to use laxatives in Constipation

Laxatives are to be used in situations where straining will exacerbate pre-existing medical/surgical conditions. The conditions are:

  1. Angina
  2. Risk of rectal bleeding
  3. Increased risk of anal tear

Other conditions that will necessitate the use of laxatives include the following:

  • In drug-induced constipation
  • When it is needed to clear the alimentary tract before surgery or radiological procedures

Non-drug treatment for Constipation

  • Avoid precipitants
  •  Eat high fibre diet (including fruits and vegetables).
  • Take adequate fluid
  • Megacolon: Saline enema
  • Surgical: resection of large bowel

Drug treatment

A. Management of Constipation in Adults

1st Line Treatment

Evidence Rating: [C]

  • Bisacodyl, oral, 10-20 mg at night

Or

  • Senna, oral, 15-30 mg at bedtime (maximum 70-100 mg daily). Doses above 70 mg should be divided 12 hourly

Or

  • Lactulose, oral, 15-30 ml daily until response, then 10-20 ml daily

2nd Line Treatment

Evidence Rating: [C]

  • Bisacodyl, rectal, 10 mg in the morning

Or

  • Glycerol suppositories, rectal, 4 g at night

Or

  • Liquid paraffin, oral, 10-30 ml at night

 Or

Milk of Magnesia, oral, 5-10 ml in a glass of water, 12-24 hourly

B. Management of Constipation in Children

1st Line Treatment

Evidence Rating: [C]
Lactulose, oral,

  • 10-18 years: 15 ml 12 hourly
  • 5-10 years: 10 ml 12 hourly
  • 1-5 years: 5 ml 12 hourly
  • < 1 year: 2.5 ml 12 hourly

Or

Glycerol suppositories, rectal,

  • 2-5 years: 2 g at night
  • < 1 year: 1 g at night

Or

Bisacodyl, rectal,

  • > 10 years: 5 mg in the morning
  • < 10 years: on medical advice only

Or

Senna, oral,

  • 6-12 years: 5-40 ml at bedtime
  • 2-6 years: 2.5-20 ml at bedtime.

Caution

  • Do not use magnesium salts in patients with impaired renal function
  • Laxatives should generally be avoided. Most times these drugs are needed for only a few days
  • In children, laxatives should be prescribed by a healthcare professional experienced in the management of constipation in children.

Referral Criteria

The following categories of patients should be referred to a surgeon:

  • Patients with absent bowel sounds, vomiting or not passing flatus
  • Cases resistant to medical treatment
  • Any suspected surgical cause

References

  1. John Hopkins Medicine: Constipation
  2. Cleveland Clinic: Constipation