Constipation (Adults)
💡 Constipation is common, usually benign, but always rule out bowel obstruction first 🚨
(look for distension, vomiting, absent bowel sounds, hernial orifices, AXR findings).
⚠️ Avoid stimulant laxatives until obstruction excluded.
🌿 Introduction
- Rome IV criteria exist for an academic diagnosis [Rome IV link], but most clinical practice is pragmatic.
- Diet: encourage hydration 🥛, mobility 🚶, and fibre (aim 30 g/day). Fruits high in sorbitol (apples, pears, plums, grapes, raspberries, prunes) are particularly helpful.
- Normal variation: some people pass stool twice daily, others twice weekly.
🧠 Anatomy & Physiology of Defaecation
- Colon: Absorbs water, compacts stool.
- Rectum: Storage; stretch receptors trigger defaecation reflex.
- Anus:
- Internal sphincter = involuntary (smooth muscle).
- External sphincter = voluntary (skeletal muscle).
- Puborectalis muscle: Maintains anorectal angle for continence; relaxes during defaecation to straighten the canal 💩.
🧾 Common Associations
- Childhood: Hirschsprung’s, cystic fibrosis
- Endocrine/metabolic: hypothyroid, diabetes, hypercalcaemia, pregnancy
- Neurological: Parkinson’s, MS, spinal cord disease
- Structural: colon cancer, diverticulitis, haemorrhoids
- Medications 💊: opiates, antidepressants, diuretics, CCBs, iron, anticholinergics, NSAIDs, aluminium antacids
- Acute illness: immobility, dehydration
🚩 Red Flags (Investigate)
- PR bleeding, weight loss, family history of colorectal cancer
- Tenesmus, anorexia, night sweats, fever, ↑ inflammatory markers
- Abdominal mass, distension, or pain on PR exam
💊 Laxative Classes
| Class | Examples | Use | Notes |
|---|
| Bulk-forming | Ispaghula husk (Fybogel) | General first-line | Needs good hydration; avoid in obstruction |
| Osmotic | Macrogol (Movicol), Lactulose | Hard stools, opioid-induced | Can cause bloating & flatulence |
| Stimulant | Senna, Bisacodyl, Sodium Picosulfate | Soft stool with poor propulsion | Hydrolysed in colon; avoid if obstruction |
| Stool softener | Docusate | Adjunct, mild stimulant effect | Useful in opioid-induced constipation |
| Prokinetic | Prucalopride | Severe chronic constipation | 5HT4 agonist, use with caution in IHD |
| Rectal | Phosphate / Microlax / Arachis oil enema | Disimpaction, rapid relief | Avoid arachis oil if peanut allergy |
🏥 In-Hospital Constipation Pearls
- Common triggers: immobility, dehydration, opiates/codeine.
- Always examine the rectum (is there hard stool in the rectum?).
- Stop causative drugs if possible.
- Escalation for disimpaction: Microlax → Phosphate → Arachis oil → Manual removal.
💡 Toileting & Lifestyle Advice
- Encourage unhurried, regular routine ⏰.
- Respond promptly to urge to defecate.
- Support mobility and privacy.
- Ensure supported seating for frail patients.
⚠️ Cautions with Laxatives
- Avoid in suspected obstruction, perforation, paralytic ileus, toxic megacolon, Crohn’s/UC flare.
- Specific cautions:
- Lactulose in galactosaemia
- Bisacodyl in severe dehydration
- Arachis oil enemas in peanut allergy
- Prolonged overuse → electrolyte imbalance (esp. hypokalaemia).
Cases - Constipation in Adults 🚽
- Case 1 - Functional Constipation (Dietary/Low Fibre) 🥖:
A 45-year-old man presents with infrequent, hard stools (once every 4–5 days), bloating, and straining. No red-flag symptoms. Diet low in fibre, high in processed foods.
Diagnosis: Functional constipation due to poor dietary fibre intake.
Management: Lifestyle changes (increase fibre, fluids, exercise); bulk-forming laxatives if required.
- Case 2 - Opioid-Induced Constipation 💊:
A 62-year-old woman on long-term morphine for metastatic breast cancer reports painful, hard stools and incomplete evacuation.
Diagnosis: Opioid-induced constipation.
Management: Regular stimulant + osmotic laxatives; consider peripherally acting opioid antagonists (e.g. naloxegol) if refractory.
- Case 3 - Constipation with IBS-C 🌿:
A 35-year-old woman complains of alternating constipation and bloating with abdominal discomfort, relieved by passing stool. No alarm features, colonoscopy previously normal.
Diagnosis: Irritable bowel syndrome (constipation predominant).
Management: Dietary advice (low FODMAP diet), osmotic laxatives (PEG), consider linaclotide if refractory.
- Case 4 - Secondary Constipation due to Hypothyroidism 🦋:
A 70-year-old man presents with lethargy, weight gain, cold intolerance, and constipation. Exam: dry skin, bradycardia. TFTs: TSH ↑, T4 ↓.
Diagnosis: Hypothyroidism with secondary constipation.
Management: Thyroxine replacement; short-term laxatives if symptomatic.
Teaching Commentary 🧠
Constipation is common, but in adults always think of:
- Primary/functional (diet, IBS, slow transit).
- Secondary (drugs e.g. opioids, metabolic e.g. hypothyroid, hypercalcaemia, neurological).
- Obstructive (colorectal cancer, strictures).
⚠️ Red flags: weight loss, anaemia, rectal bleeding, new onset >50 yrs → urgent colonoscopy.
Management is stepwise: lifestyle → bulk-forming laxatives → osmotic → stimulant → specialist referral if refractory.
