Key Facts

Constipation is one of the most common and distressing symptoms in palliative care. Prevention is key, particularly with opioid use.

Epidemiology

• 50-90% of palliative care patients experience constipation
• Almost universal with opioid therapy
• Often undertreated despite being predictable and preventable

Aetiology

• Medications: opioids (most common cause), anticholinergics, 5HT3 antagonists (ondansetron), iron, calcium
• Disease-related: intra-abdominal tumour, spinal cord compression, hypercalcaemia, autonomic neuropathy
• General: reduced oral intake, dehydration, immobility, weakness, confusion

Pathophysiology

• Opioid-induced: μ-receptor activation in myenteric and submucosal plexus → reduced peristalsis, increased segmental contractions, increased water absorption, increased anal sphincter tone
• Tolerance to constipation does NOT develop (unlike nausea, sedation)
• Reduced mobility and oral intake compound the problem
• Dehydration increases colonic water absorption further

Symptoms

• Infrequent bowel movements
• Hard stools (Bristol 1-2)
• Straining
• Abdominal bloating, discomfort, pain
• Nausea and anorexia (from faecal loading)
• Overflow diarrhoea (faecal impaction)

Complications in Palliative Care

• Faecal impaction with overflow
• Nausea and vomiting (impairs oral medication absorption)
• Urinary retention
• Delirium
• Intestinal obstruction
• Rectal pain and haemorrhoids

Red Flags

• Absolute constipation with vomiting/distension (bowel obstruction)
• New constipation in cancer patient (spinal cord compression, bowel obstruction)
• Faecal impaction causing delirium
• Overflow diarrhoea being treated with anti-diarrhoeals (dangerous mistake)

Bedside

• Abdominal palpation (faecal loading)
• DRE (impaction, rectal mass)
• Bowel chart (frequency, Bristol Stool type)
• Medication review

Bloods

• Calcium (hypercalcaemia)
• U&Es (dehydration)
• TFTs (hypothyroidism, if new presentation)

Imaging

• AXR: if significant faecal loading or obstruction suspected
• CT abdomen: if bowel obstruction suspected

Special Tests

• Generally clinical assessment is sufficient in palliative care

Non-pharmacological

• Maintain oral fluid intake where possible
• Encourage mobility (as tolerated)
• Privacy and comfort for toileting
• Footstool (optimal defaecation position)

Pharmacological

• Prevention with all opioids:
  • Senna 15mg ON (stimulant) + docusate 100mg BD (softener)
  • Or macrogol (Movicol) 1-2 sachets daily
• Treatment escalation:
  • Step 1: Senna + docusate → increase doses (senna up to 30mg BD; docusate up to 200mg TDS)
  • Step 2: Add/switch to macrogol 1-3 sachets daily
  • Step 3: Add bisacodyl 10mg ON (stimulant)
  • Step 4: Rectal measures — glycerine suppositories, bisacodyl suppositories, phosphate enema, arachis oil enema (soften hard impaction overnight then phosphate enema)
• Faecal impaction:
  • Soft: high-dose macrogol (8 sachets/day for up to 3 days)
  • Hard: arachis oil enema overnight → phosphate enema; digital manual evacuation (under sedation with midazolam if needed)
• Refractory OIC:
  • Naloxegol 25mg OD (oral PAMORA; blocks peripheral μ-receptors without affecting central analgesia)
  • Methylnaltrexone 12mg SC (alternative PAMORA; for patients who cannot swallow)
• Bowel obstruction: see specific management (avoid stimulant laxatives; medical management with hyoscine + cyclizine ± octreotide)

Surgical/Interventional

• Manual evacuation (for hard impaction in rectum)
• Stoma formation (rarely; for intractable obstruction)

Referral Criteria

• Refractory constipation despite optimised laxatives: specialist palliative care
• Suspected bowel obstruction: surgical/oncological review
• Significant faecal impaction causing complications: urgent assessment

• Prophylactic laxatives prevent OIC in most patients
• Constipation in palliative care is treatable but requires proactive management
• Untreated constipation causes significant distress, nausea, and impairs oral medication absorption
• Naloxegol/methylnaltrexone effective in 40-50% of refractory OIC cases
• Bowel function should be assessed at every palliative care review

Stepwise Approach to Constipation in Palliative Care

Rectal Measures for Faecal Impaction