Key Facts

Constipation in older adults is often multifactorial and requires a systematic approach to identify and address reversible causes before escalating laxative therapy.

Epidemiology

• 20-30% of community-dwelling >65; up to 50% in care homes
• More common in women and with increasing age
• A common reason for GP consultation and A&E attendance

Aetiology

• Medications: opioids (most common drug cause), anticholinergics, calcium supplements, iron, antipsychotics, tricyclic antidepressants
• Lifestyle: low fibre diet, inadequate fluid intake, immobility
• Metabolic/endocrine: hypothyroidism, hypercalcaemia, diabetes (autonomic neuropathy)
• Neurological: Parkinson's disease, stroke, spinal cord disease, MS
• Structural: colorectal cancer, diverticular stricture, pelvic organ prolapse, anal fissure
• Functional: slow-transit constipation, pelvic floor dyssynergia

Pathophysiology

• Slow-transit constipation: reduced colonic motility (fewer high-amplitude propagating contractions)
• Pelvic floor dyssynergia: paradoxical contraction of puborectalis during defaecation
• Opioid-induced: μ-receptor activation in GI tract → reduced peristalsis, increased water absorption, increased sphincter tone
• Immobility: reduced colonic motility and gravitational assist

Symptoms

• Infrequent bowel movements (<3/week)
• Straining at stool
• Hard, lumpy stools (Bristol 1-2)
• Sensation of incomplete evacuation
• Abdominal bloating and discomfort
• Digital manoeuvres to assist evacuation

Complications

• Faecal impaction (with overflow diarrhoea — often misdiagnosed as diarrhoea)
• Delirium
• Urinary retention and incontinence
• Rectal prolapse
• Stercoral ulceration and perforation (rare, serious)
• Volvulus
• Haemorrhoids and anal fissure

Red Flags

• New-onset constipation in >60 (consider malignancy)
• Change in bowel habit with rectal bleeding
• Weight loss
• Palpable abdominal or rectal mass
• Iron deficiency anaemia
• Absolute constipation with vomiting and abdominal distension (obstruction)

Bedside

• Abdominal examination: distension, palpable faecal loading
• Digital rectal examination: faecal impaction, rectal mass, anal tone, prolapse
• Bristol Stool Chart: record stool consistency
• Medication review

Bloods

• TFTs (hypothyroidism)
• Calcium (hypercalcaemia)
• FBC (iron deficiency anaemia → malignancy)
• U&Es (dehydration)
• Blood glucose/HbA1c (diabetic autonomic neuropathy)

Imaging

• AXR: faecal loading (not routine; useful if impaction/obstruction suspected)
• CT abdomen: if malignancy or obstruction suspected

Special Tests

• FIT (faecal immunochemical test): if colorectal cancer suspected (>60 with change in bowel habit)
• Colonoscopy: if red flags for malignancy
• Transit study (Sitzmarks): if slow-transit constipation suspected (specialist)
• Anorectal manometry and defaecating proctogram: if pelvic floor dyssynergia suspected (specialist)

Non-pharmacological

• Lifestyle measures: increase dietary fibre gradually (25-30g/day), adequate fluid intake (1.5-2L/day), regular physical activity
• Toileting routine: regular time after meals (utilise gastrocolic reflex), adequate time, correct positioning (feet elevated on footstool)
• Medication review: stop/change offending medications where possible

Pharmacological

• Step 1 — Bulk-forming: ispaghula husk (Fybogel) 1 sachet BD (requires adequate fluid intake; avoid if immobile/fluid-restricted)
• Step 2 — Osmotic: macrogol (Movicol) 1-3 sachets daily (NICE first-line for most patients); lactulose 15-30ml BD (alternative)
• Step 3 — Stimulant: senna 15-30mg ON; bisacodyl 5-10mg ON
• Combination: often needed; senna + docusate (softener + stimulant)
• Faecal impaction: high-dose macrogol (Movicol 8 sachets/day for up to 3 days) for soft impaction; glycerine suppositories or phosphate enema for rectal loading; manual evacuation under sedation if necessary
• Opioid-induced constipation: prophylactic senna + docusate; if refractory: naloxegol 25mg OD (peripherally acting μ-opioid receptor antagonist) or methylnaltrexone 12mg SC
• Prucalopride 1mg OD (5-HT4 agonist): for chronic constipation when two laxatives have failed (specialist initiation)
• Linaclotide 290mcg OD: for IBS-C if standard laxatives fail

Surgical/Interventional

• Manual evacuation: for hard faecal impaction in rectum
• Transanal irrigation: for neurogenic bowel
• Surgery: very rarely needed; subtotal colectomy for refractory slow-transit constipation (specialist)

Referral Criteria

• Red flags for malignancy: 2-week wait (NICE NG12)
• Failed two laxatives over adequate trial: specialist referral
• Suspected pelvic floor dyssynergia: specialist investigation
• Recurrent faecal impaction: continence service/geriatric assessment

• Lifestyle measures + appropriate laxatives effective in majority of cases
• Macrogol: preferred first-line; well-tolerated; effective for both treatment and prevention
• Faecal impaction: recurrence common without ongoing bowel management
• Chronic constipation impairs quality of life and is associated with increased healthcare utilisation
• Opioid-induced constipation does not resolve with tolerance (unlike nausea); always needs proactive management

Bristol Stool Chart

Stepwise Approach to Laxatives