Constipation

High-Yield Tips

• Think about what the cause of the constipation is (primary vs secondary). This will affect aperient choice.
• Aperients you'll likely use in hospitals include Movicol or coloxyl + senna. Movicol is safe to use for prolonged periods, but senna isn't. Check local guidelines or eTG for dosing.

Definition

Infrequent passage of stool (generally ≤ 3 bowel movements per week) associated with:

• Straining to defecate
• Passage of hard stools
• Tenesmus
• Need for self-digitation to evacuate stool

Primary vs secondary

Primary constipation

• Aka functional constipation
• Caused by poor diet and insufficient exercise

Secondary constipation

• Caused by another pathological process

Aetiology

Primary constipation

1. Insufficient dietary fibre and/or water
2. Immobility or ↓ mobility

Secondary constipation

1. Gastrointestinal causes (e.g. malignany, ileus, bowel obstruction)
2. Medication-induced (e.g. opioids, anticholinergics, calcium channel blockers, iron supplements)
3. Endocrine (e.g. hypothyroidism, diabetes mellitus)
4. Metabolic (e.g. hypercalcaemia, hypokalaemia)
5. Neurologic (e.g. spinal cord injury, multiple sclerosis)
6. Connective tissue disorders (e.g. scleroderma, SLE)

Management

1) Non-pharmacological

1. Get patient to mobilise (immobility can contribute)
2. ↑ dietary fibre and fluid intake
3. Address stress and/or depression
4. Cease medications that may be contributing where possible
5. Treat any other underlying cause

2) Pharmacological

Oral aperients

1. Bulking agents (e.g. psyllium) sequester (hold) extra water in stool → ↑ in luminal content volume → stimulate intestinal activity
2. Osmotic agents (e.g. lactulose, macrogol [Movicol], sorbitol) are unabsorbed molecules → draw water into intestinal lumen → laxative effect
3. Stool softeners (e.g. docusate [coloxyl]) are detergents → facilitate interaction between colonic water and stool → softer stools
4. Stimulants (e.g. bisacodyl, senna; are often combined with stool softeners), following mucosal contact → water secretion + direct stimulation of enteric nerve endings
5. Lubricants (e.g. paraffin emulsion, glycerol suppository) coat stool → easier passage + alter stool composition (soften stool)

Rectal aperients (suppository and enema versions of above)

3) Manual evacuation

Resources

1. https://www.nps.org.au/australian-prescriber/articles/managing-constipation-in-adults
2. https://www.amboss.com/us/knowledge/Constipation#anker=Z201094dd54394db9146ea1e48b85f63d