Overview
Constipation
1. Clinical Overview
Summary
Constipation is characterised by infrequent bowel movements (<3 per week) and/or difficulty passing stools. It can be primary (functional) or secondary to medications, metabolic disorders, or structural causes. Most cases are functional and respond to lifestyle and medication.
Key Facts
| Aspect | Detail |
|---|---|
| Definition | <3 bowel movements/week or difficult defecation |
| Most Common Type | Functional (primary) constipation |
| Bristol Stool Chart | Type 1-2 = constipated |
| Secondary Causes | Opiates, hypothyroidism, hypercalcaemia |
| Red Flags | Consider malignancy if new onset >60y |
Clinical Pearls
- Rome IV Criteria: Straining, lumpy/hard stools, sensation of incomplete evacuation, sense of blockage, manual manoeuvres, <3 spontaneous BMs/week
- Medication review: Opioids are the most common drug cause
- Red flags: New onset in elderly, weight loss, blood in stool
2. Epidemiology
Prevalence
| Population | Prevalence |
|---|---|
| Adults | 15-20% |
| Elderly (>5) | 30-40% |
| Women | 1.5-2x more common |
Risk Factors
| Risk Factor | Notes |
|---|---|
| Low fibre intake | Diet |
| Dehydration | Insufficient fluid |
| Inactivity | Sedentary lifestyle |
| Elderly | Multifactorial |
| Medications | Opioids, anticholinergics, CCBs |
| Hypothyroidism | Metabolic cause |
| Hypercalcaemia | Metabolic cause |
3. Pathophysiology
Types of Constipation
| Type | Mechanism |
|---|---|
| Normal transit | Stool passes normally, but patient perceives difficulty |
| Slow transit | Reduced colonic motility |
| Defaecatory disorder | Pelvic floor dysfunction, dyssynergia |
| Secondary | Drugs, metabolic, structural |
Secondary Causes
| Category | Examples |
|---|---|
| Drugs | Opioids, anticholinergics, iron, CCBs, antipsychotics |
| Metabolic | Hypothyroidism, hypercalcaemia, diabetes, hypokalaemia |
| Neurological | Parkinson's, MS, spinal cord lesions |
| Structural | Colorectal cancer, stricture, megacolon |
| Other | Pregnancy, IBS-C |
4. Clinical Presentation
Rome IV Criteria for Functional Constipation
Must include ≥2 of the following for ≥3 months:
- Straining during >25% of defecations
- Lumpy or hard stools (Bristol 1-2) in >25%
- Sensation of incomplete evacuation in >25%
- Sensation of anorectal obstruction/blockage in >25%
- Manual manoeuvres to facilitate >25%
- Fewer than 3 spontaneous bowel movements per week
Associated Symptoms
| Symptom | Notes |
|---|---|
| Bloating | Common |
| Abdominal discomfort | Relieved by defecation |
| Haemorrhoids | Secondary to straining |
| Anal fissure | Hard stools |
| Faecal impaction | Frail/elderly/neurological |
5. Clinical Examination
Examination Components
| Component | Purpose |
|---|---|
| Abdominal | Masses, distension, faecal loading |
| Perineal inspection | Fissures, haemorrhoids, skin tags |
| Digital rectal exam | Stool impaction, masses, tone |
| General | Signs of hypothyroidism, dehydration |
Red Flag Signs
| Finding | Concern |
|---|---|
| Abdominal mass | Malignancy |
| Rectal mass | Rectal cancer |
| Weight loss | Malignancy |
| Iron deficiency anaemia | Occult malignancy |
6. Investigations
Baseline Tests
| Test | Purpose |
|---|---|
| TFTs | Hypothyroidism |
| Calcium | Hypercalcaemia |
| Blood glucose | Diabetes |
| FBC | Anaemia (malignancy) |
Red Flag Investigation
| Test | Indication |
|---|---|
| Colonoscopy / CT colonography | Age >60 new onset, red flags |
| Faecal calprotectin | If IBD suspected |
Specialist Tests (if refractory)
| Test | Purpose |
|---|---|
| Transit study (markers) | Slow transit |
| Anorectal manometry | Defaecatory disorder |
| Defecography | Pelvic floor dysfunction |
7. Management
Lifestyle Measures
| Measure | Notes |
|---|---|
| Fluid intake | 1.5-2L/day |
| Fibre | 20-30g/day (gradual increase) |
| Exercise | Regular physical activity |
| Toileting | Respond to urge, regular routine |
| Position | Feet elevated (squatty potty) |
Pharmacological - Stepwise Approach
| Line | Drug | Mechanism |
|---|---|---|
| 1st | Bulk-forming (Ispaghula husk) | Increases stool mass |
| 2nd | Osmotic (Macrogol/Lactulose) | Draws water into gut |
| 3rd | Stimulant (Senna/Bisacodyl) | Increases gut motility |
| 4th | Prucalopride | 5-HT4 agonist (prokinetic) |
| Special | Linaclotide | IBS-C specific |
Specific Situations
| Situation | Treatment |
|---|---|
| Opioid-induced | Naloxegol (peripheral mu antagonist), or switch to oxycodone/naloxone |
| Faecal impaction | Macrogol high dose, enemas, manual evacuation |
| Defaecatory disorder | Biofeedback therapy |
8. Complications
| Complication | Notes |
|---|---|
| Haemorrhoids | Straining |
| Anal fissure | Hard stools |
| Faecal impaction | Especially elderly/immobile |
| Overflow incontinence | Around impacted stool |
| Rectal prolapse | Chronic straining |
| Sigmoid volvulus | Chronic constipation risk factor |
9. Prognosis & Outcomes
| Factor | Outcome |
|---|---|
| Lifestyle modification | Effective for many |
| Laxatives | Usually effective |
| Refractory cases | Specialist referral needed |
| Secondary causes | Treat underlying condition |
10. Evidence & Guidelines
| Organisation | Key Points |
|---|---|
| NICE CKS | Stepwise laxative approach |
| BSG | Investigation of chronic constipation |
| Rome Foundation | Diagnostic criteria |
11. Patient / Layperson Explanation
What is constipation? It's when you have difficulty passing stools, pass them less often than usual (<3 times a week), or the stools are hard and dry.
What causes it?
- Not drinking enough fluids
- Not eating enough fibre
- Not being active enough
- Some medications (especially painkillers)
- Sometimes medical conditions (thyroid, diabetes)
How can I help myself?
- Drink 1.5-2 litres of fluid per day
- Eat more fibre (fruit, vegetables, wholegrain cereals)
- Exercise regularly
- Don't ignore the urge to go
- Try putting your feet on a step when sitting on the toilet
When should I see a doctor?
- If you're over 60 and constipation is new
- Blood in your stool
- Unexplained weight loss
- Not improving with lifestyle changes and over-the-counter treatments
12. References
- NICE CKS. Constipation. 2023.
- Bharucha AE. Constipation. Best Pract Res Clin Gastroenterol. 2018.
- Drossman DA. Rome IV Functional GI Disorders. Gastroenterology. 2016.