What is the next best step for a 38-year-old female with a 4-month history of left iliac fossa pain and alternating bowel habit, who has not responded to Buscopan (hyoscyamine)?

Next Steps for 38-Year-Old Female with Left Iliac Fossa Pain and Alternating Bowel Habits

The next best step for this patient is to perform baseline investigations including full blood count, C-reactive protein or erythrocyte sedimentation rate, coeliac serology, and faecal calprotectin, followed by a colonoscopy if these tests are normal but symptoms persist despite treatment. 1

Initial Assessment

This 38-year-old female presents with:

• Left iliac fossa pain for 4 months
• Alternating bowel habits
• Failure to respond to Buscopan (an antispasmodic)

These symptoms strongly suggest irritable bowel syndrome (IBS) with alternating bowel habits (IBS-M), but appropriate investigations are needed to exclude organic disease before confirming this diagnosis.

Diagnostic Algorithm

1. Baseline Investigations:

   • Full blood count
   • C-reactive protein (CRP) or erythrocyte sedimentation rate (ESR)
   • Coeliac serology
   • Faecal calprotectin (particularly important in this case with diarrhoea component and age <45 years) 1

2. If baseline investigations are normal:

   • Make a positive diagnosis of IBS based on symptoms
   • Consider colonoscopy to exclude microscopic colitis, particularly given:
     • Female sex
     • Left iliac fossa pain (concerning for sigmoid pathology)
     • Alternating bowel habits
     • Failure to respond to first-line treatment 1

3. If baseline investigations are abnormal:

   • Proceed with appropriate further testing based on abnormalities
   • Consider urgent referral for colonoscopy if faecal calprotectin is significantly elevated (≥250 μg/g) 1

Treatment Considerations

Given that Buscopan (an antispasmodic) has failed, the next treatment options should be considered:

• For pain component: Consider tricyclic antidepressants (TCAs) at low doses, which have shown significant benefit for abdominal pain compared to placebo 1
• For alternating bowel habits: Consider dietary modifications and potentially newer agents that target the 5-HT receptor 1
• For psychological component: Assess for psychological comorbidities that may be exacerbating symptoms 1

Important Caveats

• Left iliac fossa pain must be carefully evaluated as it could represent diverticulitis of the sigmoid colon, although this is less common in younger patients 2
• In women of childbearing age, gynecological causes such as salpingitis should be considered 2
• The failure of Buscopan suggests either:
  1. The diagnosis is not IBS
  2. The IBS is moderate to severe and requires more aggressive treatment
  3. There are psychological factors affecting treatment response 1

Follow-up Plan

• If diagnosis of IBS is confirmed, explain that IBS is a chronic disorder with recurrent fluctuating symptoms that can be triggered by stress, intercurrent illnesses, drugs, and often the act of eating 1
• Reassess in 3-6 weeks after initiating new treatment 1
• If symptoms persist despite appropriate treatment, consider referral to gastroenterology for further specialized evaluation 1

The key to managing this patient is to exclude organic disease with appropriate investigations while simultaneously moving forward with treatment options beyond the failed antispasmodic therapy.