Irritable Bowel Syndrome (IBS)

Aetiology:** Multifactorial; contributions from gut-brain axis dysregulation, visceral hypersensitivity, altered gut motility, intestinal microbiota changes, and psychosocial factors (e.g., stress, anxiety).

Pathophysiology:** Abnormalities in gut-brain communication lead to heightened pain perception (visceral hypersensitivity), dysmotility, and immune activation with low-grade inflammation in some cases.

Common symptoms:**

• Recurrent abdominal pain or discomfort relieved by defecation.
• Altered stool frequency or form (e.g., loose/watery or hard/lumpy stools).
• Bloating, distension, and mucus in stool.

Subtypes:** IBS-D (diarrhoea-predominant), IBS-C (constipation-predominant), IBS-M (mixed).

Red-flag symptoms (suggestive of organic disease):**

• Unintended weight loss, nocturnal symptoms, fever, rectal bleeding, anaemia, family history of colorectal cancer or inflammatory bowel disease.

Clinical diagnosis:** Based on Rome IV criteria (recurrent abdominal pain ≥1 day/week for ≥3 months, associated with ≥2 of: related to defecation, change in stool frequency, change in stool form).

Exclusion of alarm features:** Guide needs further testing.

Limited testing (as indicated):**

• CBC, CRP, ESR, celiac serology, thyroid function tests.
• Faecal calprotectin (to distinguish from IBD).
• Colonoscopy (if alarm features, age >50, or family history of colorectal cancer).

Non-pharmacological:**

• Dietary modifications: Low FODMAP diet (fermentable oligo-, di-, monosaccharides, and polyols), fibre supplementation (e.g., psyllium).
• Stress reduction: Cognitive behavioural therapy, gut-directed hypnotherapy, and regular exercise.

Pharmacological (symptom-targeted):**

• • Antispasmodics (e.g., hyoscine, dicyclomine) for pain.
  • Antidiarrheals (e.g., loperamide) for IBS-D.
  • Laxatives (e.g., polyethene glycol) for IBS-C.
  • Gut-specific neuromodulators (e.g., tricyclic antidepressants, SSRIs) for pain and global symptoms.
  • Rifaximin (for IBS-D with bloating), lubiprostone/linaclotide (for IBS-C).

• Reduced quality of life:** Chronic pain, anxiety, depression, social and occupational impairment.
• Nutritional deficiencies** (if dietary restrictions are overly stringent).
• Unnecessary procedures** due to misdiagnosis or overlapping symptoms.

Prevention:** No known prevention; stress management and healthy diet may reduce flare-ups.

Follow-up:**

• Regular monitoring of symptoms and treatment response.
• Reassessment if new alarm features develop or symptoms change significantly.
• Long-term focus on symptom control and quality of life rather than cure.