Constipation Summary

Definition

  • Unsatisfactory defecation
  • Infrequent/difficult stool passage
  • Sensation of incomplete emptying
  • Chronic: ≥12 weeks in 6 months

Key Causes

  • Low fiber diet
  • Inadequate fluids
  • Lack of exercise
  • Medications (opioids)
  • Neurological conditions

Assessment

  • Abdominal examination
  • Rectal examination essential
  • Assess for faecal loading
  • Check for overflow incontinence

Laxative Ladder

  • Step 1: Bulk-forming agents
  • Step 2: Osmotic laxatives
  • Step 3: Stimulant laxatives
  • Special: Opioid constipation

Faecal Impaction

  • High-dose oral macrogol
  • Add stimulant if needed
  • Suppositories/enemas
  • Manual evacuation if severe

Constipation

Definition

Constipation is unsatisfactory defecation because of infrequent stools, difficult stool passage, or the sensation of incomplete emptying. Stools are often dry and hard or lumpy, and may be abnormally large or small.

Chronic constipation usually describes symptoms present for at least 12 weeks in the preceding six months.

Faecal loading/impaction is retention of faeces to the extent that spontaneous evacuation is unlikely.

Overflow incontinence is leakage of liquid stool from the proximal colon around impacted faeces.

Causes and Risk Factors

Social Factors

  • Low fibre diet or low calorie intake
  • Lack of exercise or reduced mobility
  • Difficult access or privacy to the toilet

Psychological Factors

  • Eating disorders
  • History of sexual abuse
  • Anxiety or depression

Physical Factors

  • Female sex
  • Older age
  • Pyrexia, dehydration, immobility

Secondary Causes

Drugs

  • Opioids
  • Anticholinergics
  • Calcium channel blockers
  • Iron supplements

Endocrine/Metabolic

  • Diabetes mellitus (with autonomic myopathy)
  • Hypercalcaemia/hypermagnesaemia
  • Hypokalaemia
  • Hypothyroidism
  • Uraemia

Neurological

  • Autonomic neuropathy
  • Cerebrovascular disease
  • Multiple sclerosis
  • Parkinson's disease
  • Spinal cord injuries

Structural

  • Anal fissures
  • Haemorrhoids
  • Colonic strictures
  • Inflammatory bowel disease
  • Obstructive colonic mass lesions

Complications

Chronic Constipation

  • Haemorrhoids or anal fissure
  • Progressive faecal retention with rectal distension
  • Loss of sensory and motor function
  • Faecal loading and impaction

Faecal Loading/Impaction

  • Faecal incontinence (embarrassing/distressing)
  • Megacolon (chronic dilatation)
  • Bowel obstruction, perforation, or ulceration
  • Recurrent UTIs, obstructive uropathy
  • Rectal bleeding
  • Rectal prolapse

Diagnosis

Suspected if:

  • Infrequent stools, difficulty passing stools, or sensation of incomplete emptying
  • Lower abdominal pain/discomfort, distension, or bloating

In Elderly Consider if:

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

Faecal Loading/Impaction Suspected if:

Examination

General

  • Assess for weight loss and nutritional status
  • Abdominal examination for pain, distension, masses
  • Palpable colon (retained faecal masses)

Rectal Examination

  • Anal fissures, haemorrhoids, skin tags
  • Rectal prolapse, rectocele
  • Skin erythema/excoriation (faecal leakage)
  • Resting anal sphincter tone
  • Rectal masses (faecal mass indents with pressure)
  • Pelvic floor dysfunction (paradoxical contraction)
  • Leakage of stool; rectal/anal pain

Management

Laxative Stepladder Approach

1 First-line: Bulk-forming laxatives (ispaghula husk) - except in opioid-induced constipation
2 If stools remain hard: Add/switch to osmotic laxative (macrogol or lactulose)
3 If stools soft but difficult to pass: Add stimulant laxative (bisacodyl, senna)

Faecal Loading/Impaction Management

  • Hard stools: High dose oral macrogol
  • Soft stools: Add oral stimulant laxative (bisacodyl, senna, glycerol)
  • Insufficient response: Consider suppository (bisacodyl ± glycerol) or mini-enema (docusate, sodium citrate)
  • Still inadequate: Sodium phosphate retention enema

General Advice

Opioid-induced Constipation

  • Do not use bulk-forming laxatives
  • Start with osmotic + stimulant laxative combination
  • Consider specific opioid receptor antagonists if severe
  • Prophylactic laxatives often required with opioid therapy

When to Refer

Urgent Referral

  • Suspected bowel obstruction
  • Severe abdominal pain
  • Rectal bleeding with constipation
  • Suspected malignancy (weight loss, anaemia)

Routine Referral

  • Failed maximal medical therapy
  • Suspected Hirschsprung's disease (children)
  • Chronic constipation with faecal incontinence
  • Suspected pelvic floor dysfunction

Summary

  • Constipation is symptom-based with infrequent/difficult defecation
  • Chronic constipation = symptoms ≥3 months
  • Assess for secondary causes (drugs, endocrine, neurological)
  • Examination should include abdominal and rectal assessment
  • Management involves lifestyle changes + laxative stepladder
  • Special approach needed for opioid-induced constipation
  • Refer if red flags present or treatment failure