Constipation in Adults

Overview

Definitions

Constipation describes problems with defecation due to hard stools, difficulty passing them, or the sensation of incomplete emptying or anorectal blockage. Chronic constipation is where these symptoms are present for at least 3 months.

Faecal impaction (or loading) describes the retention of faeces to the point where spontaneous passage is unlikely.

Overflow faecal incontinence (also known as encopresis or bypass soiling) describes leakage of liquid stool around impacted faeces.

Types

Constipation can be divided into:

• Primary (or idiopathic) – such as irritable bowel syndrome-C (IBS-C)
• Secondary (or organic) – constipation caused by an underlying cause such as a drug or medical condition

Secondary Causes

• Drugs:
  • Opioid analgesics (e.g. codeine or morphine)
  • Anticholinergic drugs (e.g. tricyclic antidepressants)
  • Some calcium-channel blockers, especially verapamil
  • Antipsychotics (e.g. quetiapine and clozapine)
• Structural disorders:
  • Anal fissures
  • Haemorrhoids
  • Colonic strictures (e.g. some may occur in Crohn’s disease)
  • Inflammatory bowel disease
  • Obstruction (e.g. colorectal cancer)
  • Pelvic masses (e.g. the foetus during pregnancy or uterine fibroids)
  • Diverticulosis
• Endocrine and metabolic disorders:
  • Hypothyroidism
  • Hypercalcaemia and hyperparathyroidism
  • Diabetes mellitus – if autonomic neuropathy develops
  • Hypokalaemia
• Neurological and neuromuscular disorders:
  • Stroke
  • Multiple sclerosis
  • Parkinson’s disease
  • Spinal cord injury
  • Central nervous system tumours
  • Systemic sclerosis

Presentation

Overview

Patients may present with problems with defecation, and may describe passing stools infrequently, difficulty passing stools, or feel a sensation of incomplete emptying or blockage:

• Bowel movements <3 times a week may be considered constipation
  • Constipation is generally considered when stools are passed less frequently than what is normal for the patient
• There may be additional symptoms such as abdominal pain, discomfort, or bloating

Elderly patients may have non-specific symptoms:

• Confusion or delirium
• Overflow diarrhoea
• Nausea, vomiting, or loss of appetite
• Urinary retention

Faecal Impaction

Faecal impaction should be suspected if any of the following are present:

• Hard, lumpy stools that may be:
  • Large and infrequent (e.g. every 7-10 days) or
  • Small and frequent (e.g. every 2-3 days)
• Using manual methods to remove faeces
• Overflow incontinence or loose stool

Red flags

The following red flags may suggest an increased risk of a secondary cause requiring further investigation:

• Age >50 years
• Weight loss
• Associated symptoms such as rectal bleeding, tenesmus, or discharge
• Blood in the stool
• Recent onset of symptoms
• Symptoms suggesting obstruction
• Rectal prolapse
• Change in stool calibre

Investigations

Most patients do not require investigation. Some other tests that may be considered are:

• Full blood count
• Urea and electrolytes (U&Es)
• Serum calcium
• Thyroid function tests
• Abdominal x-ray
• Colonoscopy
• Barium enema

Management

Overview

Lifestyle advice regarding increasing fibre intake should be given. Example foods are whole grains, fruits, and vegetables. Management involves:

• Investigate and manage the underlying cause
• Rule out faecal impaction
• Give lifestyle advice
• Consider laxatives – see Laxatives for more information regarding the types used:
  • 1^st-line: bulk-forming laxatives
    • Avoid if the patient has opioid-induced constipation, offer an osmotic laxative and a stimulant laxative instead
  • If ineffective, switch to an osmotic laxative
  • If an osmotic laxative is ineffective, consider lactulose
• Prucalopride may be considered for chronic constipation if other options fail

Faecal impaction

• If hard stools present: high-dose oral macrogol
• If soft stools present or ongoing hard stools after a few days of oral macrogol treatment, consider starting or adding an oral stimulant laxative
• If inadequate response or too slow, consider:
  • Bisacodyl suppository, glycerol alone, or glycerol + bisacodyl
  • Mini enema e.g. docusate or sodium citrate

Complications

Chronic constipation can lead to:

• Faecal impaction
• Progressive faecal retention
• Rectal distention and reduced sensorimotor function
• Haemorrhoids
• Anal fissures

Faecal impaction can lead to more serious complications:

• Faecal incontinence
• Chronic colon dilatation
• Bowel obstruction, perforation, or ulceration
• Obstructive uropathy
• Rectal bleeding
• Rectal prolapse