What is the appropriate workup and treatment for a patient with irritable bowel syndrome (IBS)?

Workup and Treatment for Irritable Bowel Syndrome (IBS)

The diagnosis of IBS should be made confidently based on symptom criteria (Rome criteria) with limited investigations, followed by a treatment approach targeting predominant symptoms including dietary modifications, lifestyle changes, and appropriate pharmacological therapies based on IBS subtype. 1

Diagnostic Approach

Making a Positive Diagnosis

• Use Rome criteria for diagnosis: At least 12 weeks of abdominal pain/discomfort in the preceding 12 months with 2 of 3 features:
  • Pain relieved with defecation
  • Onset associated with change in stool frequency
  • Onset associated with change in stool form 1
• Classify IBS by predominant bowel pattern:
  • IBS with constipation (IBS-C)
  • IBS with diarrhea (IBS-D)
  • Mixed IBS (IBS-M)

Limited Investigations

• Basic testing only for typical presentations without alarm features:

  • Complete blood count
  • Stool for occult blood
  • Serum chemistries 1

• Additional testing only for specific indications:

  • Colonoscopy: Only for patients with alarm symptoms/signs, age ≥50 years, or IBS-D patients with risk factors for microscopic colitis (female sex, age ≥50, autoimmune disease, nocturnal diarrhea, duration <12 months, weight loss, or use of NSAIDs/PPIs/SSRIs) 1
  • For IBS-D with atypical features (nocturnal diarrhea, prior cholecystectomy): Consider testing for bile acid diarrhea 1
  • For defecatory disorders: Consider anorectal physiology tests 1

Avoid Unnecessary Testing

• No role for routine colonoscopy in typical IBS without alarm features
• No role for hydrogen breath testing or exocrine pancreatic insufficiency testing 1

Treatment Algorithm

First-Line Approach for All IBS Patients

1. Clear explanation and education:

   • Explain IBS as a disorder of gut-brain interaction
   • Emphasize benign nature but chronic course
   • Discuss how diet, stress, and emotional responses impact symptoms 1

2. Lifestyle modifications:

   • Regular exercise (improves constipation and overall symptoms)
   • Adequate sleep hygiene
   • Stress management techniques 1

3. Dietary interventions:

   • For IBS-C: Increase dietary fiber (especially soluble fiber)
   • For IBS-D: Reduce intake of gas-producing foods, caffeine, alcohol
   • Consider low FODMAP diet for moderate-to-severe symptoms (ideally with dietitian guidance)
   • For psychological-predominant symptoms: Consider Mediterranean diet 1

Second-Line Treatment Based on Predominant Symptom

For IBS with Pain:

• Antispasmodics (e.g., dicyclomine) for cramping pain 1
• Low-dose tricyclic antidepressants (e.g., amitriptyline) for persistent pain 1

For IBS-D:

• Loperamide 4-12 mg daily (regularly or prophylactically) 1
• Rifaximin 550 mg three times daily for 14 days (for non-constipated IBS) 2
• Cholestyramine for those with suspected bile acid diarrhea 1

For IBS-C:

• Lubiprostone 8 mcg twice daily 3
• Psyllium/ispaghula husk if bran exacerbates symptoms 1

For Bloating:

• Trial of reducing fiber/lactose/fructose as relevant 1

Third-Line Approaches for Refractory Symptoms

1. Psychological therapies:

   • Cognitive behavioral therapy
   • Gut-directed hypnotherapy
   • Mindfulness-based stress reduction 1

2. For severe symptoms with psychological comorbidity:

   • SSRIs for concurrent anxiety/depression (preferred over TCAs for mood disorders) 1
   • Consider psychiatric referral for serious psychiatric disease 1

Special Considerations

Managing Comorbid Mental Health Issues

• Adjust visit duration/frequency to accommodate mental health needs
• For moderate-severe anxiety/depression: Refer to gastropsychologist or psychiatrist 1
• Consider SSRIs for patients with predominant anxiety/depression 1

Common Pitfalls to Avoid

1. Overinvestigation: Extensive testing rarely changes management and may increase patient anxiety
2. Promising cure: Emphasize symptom management rather than cure
3. Ignoring psychological factors: Address anxiety, depression, and stress as they significantly impact symptoms
4. Medication overuse: Avoid long-term use of opioids or excessive antimotility agents
5. Failing to follow up: Regular follow-up improves outcomes and patient satisfaction

By following this structured approach to diagnosis and treatment, most patients with IBS can achieve significant improvement in symptoms and quality of life, even though complete resolution of symptoms may not be possible.