What is the best strategy to treat severe constipation?

Management of Severe Constipation: A Stepwise Approach

For severe constipation, the most effective treatment strategy is to begin with osmotic laxatives (polyethylene glycol/PEG) combined with stimulant laxatives (senna or bisacodyl), followed by escalation to prescription medications if needed. 1

Initial Assessment and Management

Step 1: Rule Out Impaction

• Perform digital rectal examination to check for fecal impaction
• If impaction is present:
  • Use glycerine suppositories or mineral oil retention enema 1
  • Consider manual disimpaction with pre-medication (analgesic/anxiolytic) for severe cases 1
  • Follow with maintenance bowel regimen to prevent recurrence 2

Step 2: First-Line Pharmacological Treatment

• Combination therapy is recommended for severe constipation:
  • Osmotic laxative: Polyethylene glycol (PEG) 17g daily 1
  • PLUS stimulant laxative: Senna 8.6-17.2mg at bedtime or bisacodyl 10-15mg 2-3 times daily 2, 1
• PEG is strongly endorsed in systematic reviews with no significant electrolyte shifts and excellent tolerability 1
• Goal: One non-forced bowel movement every 1-2 days 2

Non-Pharmacological Interventions

• Increase dietary fiber to approximately 30g/day (fruits, vegetables, whole grains) 2, 1
• Ensure adequate fluid intake, particularly water 1
• Increase physical activity within patient limits 2, 1
• Optimize toileting position (use footstool to assist with defecation) 2
• Attempt defecation 30 minutes after meals to utilize gastrocolic reflex 1
• Consider abdominal massage for patients with neurogenic issues 2

Treatment Escalation for Refractory Constipation

Step 3: If Inadequate Response After 2-3 Days

• Increase dose of initial agents OR
• Add second agent (ensure combination of stimulant + osmotic) 1
• Consider adding lactulose, magnesium hydroxide, or magnesium citrate 2
  • Caution: Monitor magnesium levels in renal impairment 2, 1

Step 4: For Persistent Severe Constipation

• Consider prescription medications:
  • Secretagogues: Linaclotide 145-290mcg daily 3, 1
    • Particularly effective for chronic idiopathic constipation 3
    • Improves stool frequency, consistency, and reduces straining 3
  • For opioid-induced constipation: Consider methylnaltrexone 0.15mg/kg subcutaneously every other day 2, 1

Special Considerations

Opioid-Induced Constipation

• Always start prophylactic stimulant laxative when opioids are prescribed 2, 1
• Avoid bulk-forming laxatives (psyllium) for opioid-induced constipation 2
• Consider peripheral μ-opioid receptor antagonists (PAMORAs) for refractory cases 2, 1

Elderly Patients

• Pay particular attention to assessment of elderly patients 2
• Ensure access to toilets, especially with decreased mobility 2
• PEG (17g/day) offers an efficacious and tolerable solution with good safety profile 2
• Avoid liquid paraffin for bed-bound patients due to aspiration risk 2
• Use saline laxatives cautiously due to risk of hypermagnesaemia 2

Contraindications and Cautions

• Avoid enemas in patients with:
  • Neutropenia or thrombocytopenia
  • Paralytic ileus or intestinal obstruction
  • Recent colorectal or gynecological surgery
  • Recent anal or rectal trauma 2
• Avoid bulk-forming laxatives in non-ambulatory patients with low fluid intake due to increased risk of impaction 2, 1

The evidence clearly supports a structured approach to severe constipation, beginning with combination therapy of osmotic and stimulant laxatives, while incorporating lifestyle modifications, and escalating to prescription medications when necessary. This approach has been shown to effectively manage severe constipation while minimizing complications and improving quality of life.