🩺 Constipation

Constipation is defined as the infrequent or difficult passage of stools, often associated with hard faeces and a sense of incomplete evacuation. In the UK, it is highly prevalent, particularly among the elderly and those with low fibre intake. While usually a functional or lifestyle-related issue, it can be the primary symptom of hypothyroidism, metabolic disturbance, or more seriously, colorectal cancer. Management involves lifestyle modification followed by a stepwise pharmacological approach using various classes of laxatives.

Establish the patient's 'normal' baseline and the nature of the change (frequency vs consistency). Ask about 'Bristol Stool Scale' type (Type 1-2 indicates constipation). Inquire about straining, a sense of incomplete evacuation, or the need for manual manoeuvres. It is vital to screen for 'red flag' symptoms: rectal bleeding, weight loss, and family history of bowel cancer. Medication history (opioids, iron, calcium-channel blockers, anticholinergics) and dietary habits (fibre and fluid intake) are major contributors. Ask about 'tenesmus' (the persistent urge to empty the bowel) which can indicate a rectal tumour.

Abdominal examination may reveal palpable faecal masses (typically in the left iliac fossa) and abdominal distension. A digital rectal examination (DRE) is essential to assess for faecal impaction, rectal masses, anal fissures, and sphincter tone. Assessment of perianal sensation and lower limb neurology (reflexes/power) is necessary if a neurological cause like cauda equina syndrome is suspected. General examination should look for features of hypothyroidism (dry skin, bradycardia, slow-relaxing reflexes).

Functional/Dietary Constipation, Colorectal Cancer, Irritable Bowel Syndrome (IBS), Opioid-induced Constipation, Hypothyroidism, Hypercalcaemia, Anal Fissure (causing avoidance of defecation), Parkinson's disease, Cauda Equina Syndrome.

Unexplained weight loss, rectal bleeding, iron-deficiency anaemia, nocturnal symptoms, family history of bowel cancer/IBD, or sudden change in bowel habit in patients >50.

Routine bloods include FBC (anaemia of chronic blood loss), U&Es, Calcium (hypercalcaemia causes constipation), and TFTs (hypothyroidism). Abdominal X-ray is NOT routinely recommended for simple constipation but may be used to assess for impaction or megacolon in specific clinical contexts (e.g., elderly/psychiatric patients). Colonic transit studies or anorectal manometry are reserved for specialist secondary care. The gold standard for investigating suspected malignancy (red flags or age >50) is colonoscopy or CT Colonography.

New-onset constipation in a patient over 50 is a 'red flag' for colorectal malignancy until proven otherwise. Opioids are the most common pharmacological cause of constipation; they should always be co-prescribed with a stimulant laxative. Paradoxical 'overflow' diarrhoea occurs when liquid stool leaks around a hard faecal impaction—it is frequently mismanaged with anti-diarrheals, making the impaction worse. In children, constipation is usually functional, but in neonates, failure to pass meconium within 24-48 hours should prompt investigation for Hirschsprung's disease or Cystic Fibrosis.

Aligned with the MLA content map 'Constipation'. Students must know the laxative ladder: starting with bulk-forming (e.g., ispaghula), then osmotic (e.g., macrogol/lactulose), followed by stimulant (e.g., senna/bisacodyl). Note that lactulose is a second-line osmotic due to bloating. Recognise the criteria for 2-week wait colorectal cancer referrals (NICE NG12). Knowledge of Hirschsprung’s is important for paediatric-related MLA questions.