Constipation
Aetiology of constipation
- General:
- Poor diet (lack of fibre)
- Dehydration
- Immobility
- Pain (especially post-operative)
- Medication
- Opiates
- Calcium channel blockers (Verapamil)
- Anticholinergics (Tricyclic antidepressants, phenothiazines)
- Iron supplements
- Anorectal disease
- Anal fissure
- Rectal prolapse
- Irritable bowel syndrome
- Metabolic
- Hypercalcaemia
- Hypothyroidism
- Hypokalaemia
- Intestinal obstruction
- Colorectal carcinoma
- Strictures (Crohn’s)
- Diverticular disease
- Slow bowel transit/motility disorders
- Neuromuscular
- Nerve injury/trauma
- Systemic sclerosis
- Aganglionosis (Chagas’ disease, Hirschprung’s disease)
- Psychological
- Different environment
- Previous trauma/abuse
History in constipation
- Presenting complaint
- Infrequent passage of stool (< 3x weekly)
- History of presenting complaint
- Frequency, nature and consistency of stool
- Pain on defecation
- Straining or discomfort
- Recent change in bowel habit
- Constipation alternating with diarrhoea
- Any associated blood or mucus
- Tenesmus (sensation of incomplete evacuation on defecation)
- Abdominal pain
- Systemic features
- Past medical history
- Previous bowel surgery
- Inflammatory bowel disease
- Medications
- See list of causes
- Allergies
- Family history
- Colorectal carcinoma
- Social history
- Diet
- Smoking
- Psychological history
Examination of constipation
- Most examinations will be normal
- Lymphadenopathy, abdominal mass, anaemia would be suspicious for colorectal carcrinoma
- Digital rectal examination is essential: look for fissures/haemorrhoids, impacted stool, blood/mucus
Initial management of constipation
- Most patients present with mild symptoms and need little more than taking a thorough history and a proper examination.
- Blood tests:
- FBC, Calcium, U+Es (dehydration), Thyroid function tests
- Abdominal X-ray (often performed in hospital to rule out obstruction)
- The management for most patients will be reassurance plus advice to eat plenty of fibre and keep well hydrated.
- Laxatives can be used for mild-moderate symptoms if general measures do not work:
- Bulking agents e.g. Bran, Ispaghula hulk, methycellulose
- Stimulant laxatives e.g. Senna (2 tablets/7.5mg at night), Bisacodyl, glycerol suppositories, docusate sodium (also has softening properties, up to 500mg daily in divided doses)
- Stool softeners e.g. arachis oil enemas, liquid paraffin
- Osmotic laxatives e.g. Lactulose (initially 10-15 ml twice daily but can be increased, especially in hepatic encephalopathy), phosphate enemas (useful if faecal impaction present or pre-endoscopy)
Further management of constipation
- A few patients will need further investigation and support.
- Colonoscopy and biopsies
- Barium enema
- CT abdomen
- Bowel transit studies
- Anorectal physiology studies
- Behaviour therapy
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