What is the recommended workup for a patient presenting with abdominal pain and bloating?

Workup for Abdominal Pain and Bloating

For patients presenting with abdominal pain and bloating, begin with baseline blood work (complete blood count, C-reactive protein or ESR, and coeliac serology) and add faecal calprotectin if diarrhoea is present in patients under 45 years old—this focused approach allows you to make a positive diagnosis of IBS in most cases without extensive imaging. 1

Initial Clinical Assessment

Key History Elements to Elicit

Focus your history on these specific diagnostic features 1:

• Onset and duration: When did symptoms start? This is the critical first question
• Cardinal symptom relationship: Does the patient recognize a link between their abdominal pain and altered bowel habit? Pain should be relieved/exacerbated by defecation OR associate temporally with changes in stool frequency/consistency
• Stool pattern: Use Bristol stool chart to classify predominant pattern on abnormal days
• Bloating presence: While not required for diagnosis, bloating is highly suggestive of IBS when present with pain and altered bowel habit
• Potential triggers: Post-infectious onset (present in ~10% of IBS), recent antibiotics, or psychological stress
• Extraintestinal symptoms: Back pain, urological, gynaecological symptoms, fibromyalgia, chronic fatigue
• Medications: Specifically ask about opioids and psychotropic agents
• Red flags: Objective weight loss, nocturnal symptoms, age >50 with new onset, family history of GI cancer/IBD

Baseline Laboratory Investigations

The British Society of Gastroenterology recommends this specific panel 1:

• Full blood count
• C-reactive protein OR erythrocyte sedimentation rate
• Coeliac serology
• Faecal calprotectin (if diarrhoea present AND age <45 years)
  • If ≥250 μg/g: High suspicion for IBD, proceed to colonoscopy
  • If 100-249 μg/g: Repeat off NSAIDs/PPIs; refer for colonoscopy if remains elevated

When Imaging Is NOT Needed

Most patients with typical symptoms and normal baseline labs do not require imaging 1. You can confidently make a positive diagnosis of IBS when:

• Cardinal symptoms are present (pain linked to altered bowel habit)
• Baseline investigations are normal
• No alarm features present
• No atypical features (nocturnal symptoms, severe watery diarrhoea)

The Rome IV criteria validation study showed patients meeting IBS-C criteria were 21 times more likely to have IBS-C than not, and IBS-M patients were 11 times more likely to have IBS-M after limited workup 1.

When Further Investigation IS Warranted

Alarm Features Requiring Urgent Imaging

Proceed to colonoscopy or CT imaging if 1:

• Objective weight loss
• Rectal bleeding with iron deficiency anaemia
• Family history of colorectal cancer or IBD
• Age >50 with new-onset symptoms

Note the caveat: Up to 80% of IBS patients report at least one alarm symptom, so diagnostic performance is modest 1.

Atypical Features Requiring Targeted Investigation

Consider these specific scenarios 1:

For suspected IBS-D with atypical features:

• Colonoscopy with biopsies to exclude microscopic colitis if:

  • Female, age ≥50 years
  • Coexistent autoimmune disease
  • Nocturnal or severe watery diarrhoea
  • Duration <12 months
  • Weight loss
  • Use of NSAIDs, PPIs, SSRIs, or statins

• SeHCAT scan or empiric bile acid sequestrant trial for bile acid diarrhoea

For suspected IBS-C:

• Consider anorectal manometry/balloon expulsion testing if features suggest dyssynergic defecation

Imaging for Acute Presentations

If symptoms are acute (<7 days) rather than chronic 2:

• Right upper quadrant pain: Ultrasonography is first-line 3
• Right or left lower quadrant pain: CT abdomen/pelvis with contrast 3
• Generalized acute pain: CT abdomen/pelvis with contrast 3

Critical pitfall: Always obtain beta-hCG in women of reproductive age before imaging 3.

Common Diagnostic Pitfalls to Avoid

1. Over-investigation: The yield of colonoscopy in typical IBS is extremely low, and normal results do not provide reassurance to patients 1

2. Repetitive testing: Once functional diagnosis is established with normal baseline workup, avoid repeated investigations 4

3. Assuming imaging is needed: Conventional radiography has limited diagnostic value in abdominal pain evaluation 3

4. Missing the diagnosis through inadequate history: Two minutes of active listening at consultation start improves patient confidence and outcomes 1

Making the Positive Diagnosis

When baseline investigations are normal and symptoms are typical, confidently communicate a positive IBS diagnosis 1. Explain this as a disorder of gut-brain interaction affecting visceral sensitivity, not a diagnosis of exclusion. This approach—combined with education about the chronic fluctuating nature, lack of cancer/mortality risk, and treatment targeting visceral hypersensitivity—improves patient acceptance and engagement with management 1.

The key is recognizing that abdominal pain with bloating, when accompanied by altered bowel habit and normal baseline labs, represents IBS in the vast majority of cases and does not require extensive imaging workup.