What is the differential diagnosis and recommended imaging for a patient with a history of spondelitis, experiencing ongoing epigastric pain unresponsive to proton pump inhibitors (PPIs), with epigastric tenderness, normal white cell count (WCC), elevated C-reactive protein (CRP) level, and pain that worsens when lying flat and improves when lying on the left side?

Differential Diagnosis and Imaging for Epigastric Pain Unresponsive to PPIs

Order a CT abdomen/pelvis with IV contrast immediately to evaluate for spondylodiscitis, peptic ulcer perforation, pancreatitis, and cardiac causes, while obtaining an ECG and cardiac troponins to exclude myocardial infarction. 1, 2

Critical Life-Threatening Diagnoses to Exclude First

Myocardial Infarction

• Epigastric pain can be the primary manifestation of MI, especially in patients with inflammatory conditions like spondylitis 1, 2
• Obtain ECG within 10 minutes and measure serial cardiac troponins at 0 and 6 hours—never rely on a single measurement 1, 2
• Atypical presentations include isolated epigastric pain, indigestion-like symptoms, and pain relieved by position changes 1, 2
• Your patient's positional relief (better lying on left side) does NOT exclude cardiac causes 1

Spondylodiscitis (Bacterial Spinal Infection)

• This is the most likely diagnosis given the history of spondylitis, elevated CRP of 65 mg/L, positional pain pattern, and PPI failure 3
• CRP levels of 65 mg/L are consistent with active spondylodiscitis (mean preoperative CRP in spondylodiscitis is 90 mg/dl) 3
• Normal WBC count does NOT exclude spondylodiscitis—WBC is an unspecific marker for spinal infection 3, 4
• Positional pain (worse lying flat, better on left side) is characteristic of spinal pathology with referred epigastric pain 3
• Patients with ankylosing spondylitis have elevated CRP with active disease (CRP >50 mg/L correlates with disease activity) 5, 6

Perforated Peptic Ulcer

• Presents with sudden severe epigastric pain, fever, abdominal rigidity, and absent bowel sounds 1
• Your patient lacks fever and has only epigastric tenderness (not rigidity), making this less likely but still requiring exclusion 1
• CT shows extraluminal gas in 97% of cases 1

Acute Pancreatitis

• Characterized by epigastric pain radiating to the back 1
• Check serum lipase (≥2x normal has 80-90% sensitivity/specificity) 1
• CRP of 65 mg/L is below the 170 mg/L cutoff that discriminates severe from mild pancreatitis 7

Most Likely Differential Diagnoses

1. Spondylodiscitis with Referred Epigastric Pain (Primary Concern)

• CRP 65 mg/L indicates active inflammatory/infectious process 5, 3, 6
• History of spondylitis increases risk for spinal infection 3
• Positional pain pattern (worse flat, better left lateral) suggests spinal origin 3
• PPI failure indicates non-acid-related pathology 1, 8

2. Refractory Peptic Ulcer Disease or Gastric Pathology

• PPIs heal 80-90% of duodenal ulcers and 70-80% of gastric ulcers in 2-4 weeks 1, 8
• Failure to improve suggests complicated ulcer, gastric cancer, or alternative diagnosis 1
• Epigastric tenderness without peritoneal signs suggests localized pathology 1

3. Inflammatory Bowel Disease (IBD-Associated with Spondylitis)

• Up to 30% of patients with spondyloarthritis have subclinical gut inflammation 7, 9
• CRP >50 mg/L warrants IBD evaluation in spondylitis patients 7, 9
• Epigastric pain can be presenting symptom of Crohn's disease 7

Recommended Imaging Strategy

First-Line: CT Abdomen/Pelvis with IV Contrast

• This is the gold standard for evaluating epigastric pain when diagnosis is unclear 1
• Identifies spondylodiscitis, perforation, pancreatitis, abscesses, and vascular emergencies 7, 1
• Shows extraluminar gas (97% sensitive for perforation), fluid/fat stranding (89%), and focal wall defects (84%) 1
• Evaluates spine for discitis/osteomyelitis in patients with spondylitis 3

Additional Imaging Based on CT Results

• MRI spine with contrast if CT suggests spondylodiscitis—provides superior soft tissue detail for spinal infection 3
• Upper endoscopy if CT shows gastric/duodenal pathology or is negative but symptoms persist 1

Immediate Laboratory Workup

Essential Tests

• Serial cardiac troponins at 0 and 6 hours (mandatory given epigastric pain) 1, 2
• Serum lipase (≥2x normal confirms pancreatitis) 1
• Blood cultures (if spondylodiscitis suspected—identifies bacteria in 70-80% of cases) 3
• Complete metabolic panel (assess renal function before contrast CT) 1
• Lactate level (elevated suggests ischemia or sepsis) 1

Already Available Results Interpretation

• CRP 65 mg/L: Significantly elevated, indicates active inflammation/infection 5, 3, 6
• Normal WBC: Does NOT exclude serious pathology—WBC is insensitive for spondylodiscitis, IBD, and many urgent conditions 3, 4

Critical Management Steps

Immediate Actions

1. Maintain NPO status until surgical emergency excluded 1
2. Establish IV access and provide fluid resuscitation 1
3. Continue PPI therapy (omeprazole 40 mg daily for severe symptoms) but recognize this is diagnostic—continued failure confirms non-acid etiology 1, 8
4. Avoid NSAIDs (worsen peptic ulcer disease and may mask symptoms) 1

Common Pitfalls to Avoid

• Never dismiss epigastric pain as "just GERD" in patients with elevated CRP and alarm features 1
• Do not rely on normal WBC to exclude serious pathology—CRP is far more sensitive for inflammatory conditions 5, 3, 4, 6
• Do not assume positional relief excludes cardiac causes—atypical MI presentations are common 1, 2
• In patients with spondylitis, always consider spondylodiscitis when CRP is elevated and pain has positional component 3, 6

If CT and Cardiac Workup Are Negative

• Proceed to upper endoscopy with biopsies to evaluate for refractory peptic ulcer, gastric cancer, or gastritis 1
• Consider fecal calprotectin testing (repeat twice, 15-20 days apart) to screen for IBD in spondylitis patients 7, 9
• Arrange rheumatology follow-up for spondylitis disease activity assessment using ASDAS-CRP score 7