Chronic constipation Flashcards
Probability diagnosis
Simple constipation:
- low-fibre diet,
- poor fluid intake
- lifestyle and bad habit
Slow transit (idiopathic) constipation
Normal transit (irritable bowel syndrome)
Serious disorders not to be missed
Intrinsic neoplasia:
- colon
- rectum or anus
Extrinsic malignancy (e.g. lymphoma, ovary)
Hirschsprung (children)
Pitfalls (often missed)
- Impacted faeces
- Local anal lesions (e.g. anal fissure)
- Drug/purgative abuse
- Hypokalaemia
- Depressive illness
- Acquired megacolon
- Diverticular disease
- Rarities:
- lead poisoning
- hypercalcaemia
- hyperparathyroidism
- dolichocolon (large colon)/megarectum
- Chagas disease
- systemic sclerosis
Masquerades checklist
Depression
Diabetes (rarely)
Drugs (opiates, iron, others)
Thyroid disorder (hypothyroidism)
Spinal dysfunction (severe only)
Is the patient trying to tell me something?
May be functional (e.g. depression, anorexia nervosa).
Key history
Define what exactly pt means by constipation.
- stool consistency
- frequency
- ease of evacuation
- pain on defecation
- presence of blood or mucus.
A dietary and drug history is important.
Key examination
The important aspects are abdominal palpation and rectal examination
Test perianal sensation and the anal reflex
Perform sigmoidoscopy
Key investigations
Basic tests are FBE/ESR, occult blood in stool
Consider serum calcium, potassium, CEA and TFTs
If appropriate refer for;
- sigmoidoscopy or colonoscopy
- radiological studies (e.g. CT colonography, bowel transit studies)
Diagnostic tips
Alarm symptoms;
- rectal bleedin
- recent constipation in those >40 years
- FHx of cancer.
Bleeding suggests;
- cancer
- haemorrhoids
- diverticular disorder
- inflammatory bowel disease.
Beware of hypokalaemia causing constipation in the elderly pt on diuretic treatment.
Drugs:
- analgesics
- opioids esp. codeine
- TCAs
- antacids esp. aluminium hydroxide
- Ca channel blockers
- SSRIs
- cough mixtures
- anti-cholinergics, benzodiazepines.
