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Constipation

Constipation is defined as unsatisfactory defecation characterised by infrequent stools, difficult stool passage, or defecation that is both infrequent and/or difficult.


N.B. Will be Type 1 or 2 on the Bristol Stool Chart.

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“Bristol stool chart” © Cabot Health, Bristol Stool Chart CC BY-SA 3.0 (https://creativecommons.org/licenses/by-sa/3.0/)

Risk factors:

  • Advanced age

  • Female

  • Inactivity

  • Low calorie intake

  • Low fibre diet

  • Medication e.g. anticholingerics


Causes:

  • Primary - No organic cause, and thought to be due to dysregulated function of the colon/anorectal muscles

  • Secondary - Due to:

    • Diet - low fibre

    • Drugs - opiates, anticholinergics (e.g. TCAs), antipsychotics, CCBs

    • Metabolic - hypercalcaemia

    • Endocrine - hypothyroidism

    • Neurological - parkinsonism, spinal cord lesion, DM

    • Obstruction - stricture, cancer, fissure, proctitis


Presentation

  • Infrequent stools

  • Difficulty opening bowels

  • Excessive straining (commonly used by patients to describe defacation)

  • Tenesmus (feeling of incomplete emptying)

  • Hard stools

  • Anal fissure

  • Signs of underlying medical disorder e.g. hypothyodism

  • Signs of malignancy e.g. pr bleeding, weight loss, loss of appetite, obstruction


Investigations

  • Bloods - FBC, U&Es, TFTs, Glucose

  • AXR

  • Barium enema

  • Colonoscopy if suspected malignancy

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“Significant stool throughout the colon of an 8 year old with constipation.” © James Heilman, MD CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0/)

Management

  • Treat underlying cause

  • Diet and lifestyle advice - more fibre, exercise, hydration, prunes

  • Laxatives

    • 1st line - Bulk-forming (ispaghula husk, methylcellulose) or Stool softener (docusate sodium)

    • 2nd line - Osmotic (lactulose, macrogol/movicol)

    • 3rd line - Stimulant laxatives (senna, bisacodyl)

      • Enemas or suppositories used if impacted


N.B. Bulk-forming - Work in the same way as fibre. They increase the bulk of the stools by helping them retain fluid, therefore encouraging peristalsis.


N.B. Stool softeners - Makes stool absorb more water and fat.


N.B. Osmotic - Draws water from the rest of body into bowel to soften stool.


N.B. Stimulant - Stimulates peristalsis.



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