What is the best course of action for a patient presenting with acute left upper quadrant abdominal pain that worsens with palpation, suspected to have gastric pathology such as perforation or ulcer disease?

Acute Left Upper Quadrant Abdominal Pain with Suspected Gastric Pathology

Immediate Diagnostic Approach

For a patient presenting with acute left upper quadrant abdominal pain worsening with palpation and suspected gastric perforation or ulcer, obtain CT scan of the abdomen and pelvis with IV contrast immediately as the first-line diagnostic test. 1, 2

Why CT is the Priority

• CT scan is strongly recommended as the preferred imaging modality for suspected perforated peptic ulcer (Strong recommendation, 1C evidence), providing superior diagnostic precision with 96.8% accuracy for acute abdominal pathology 1, 2, 3

• CT detects critical findings including free air from perforation, gastric wall thickening, mucosal hyperenhancement, focal outpouching from ulcerations, and active bleeding 1

• For suspected gastric perforation specifically, CT is more sensitive than plain radiography for detecting small quantities of extraluminal air, which indicates luminal perforation requiring urgent surgical intervention 1

If CT is Not Immediately Available

• Perform chest and abdominal X-ray as initial routine assessment when CT cannot be obtained promptly (Strong recommendation, 1C) 1, 2

• If free air is not seen on X-ray but clinical suspicion remains high, add water-soluble contrast either orally or via nasogastric tube (Weak recommendation, 2D) 1

• However, recognize that plain radiography detects free air in only 30-85% of perforations, making negative X-rays insufficient to rule out perforation 1

Concurrent Laboratory Evaluation

Obtain routine laboratory studies and arterial blood gas analysis immediately alongside imaging (Strong recommendation, 1D) 1, 4, 2

Essential Labs Include:

• Complete blood count (leukocytosis commonly present but non-specific) 1, 4, 2

• Metabolic panel (metabolic acidosis associated with perforation) 1, 4, 2

• Serum amylase (often elevated but non-specific) 1, 4, 2

• Arterial blood gas analysis 1, 4

Critical Caveat About Clinical Presentation

Do not be falsely reassured by equivocal physical examination findings. Peritonitis may be present in only two-thirds of patients with perforated peptic ulcer, and may be minimal or absent particularly in contained or sealed perforations 1, 2. The sudden onset of severe upper abdominal pain with tachycardia and abdominal rigidity is classic, but variable presentations are common 2.

CT Findings That Confirm Gastric Pathology

When CT is performed, look for these specific findings 1:

• Gastric wall thickening due to submucosal edema
• Mucosal hyperenhancement or fat stranding from inflammation
• Focal outpouching of mucosa from ulcerations
• Focal interruption of mucosal enhancement from ulcer crater eroding through epithelial lining
• Focal perforation with associated free air (surgical emergency)
• Hyperdense blood products at ulcer site indicating active bleeding
• Gastric outlet obstruction from edema or chronic inflammatory changes

Surgical Decision-Making

If CT confirms perforation, proceed to urgent surgical intervention. 1, 5

• Minimally invasive surgery is the preferred approach with improved outcomes compared to open techniques 5

• Omental patch closure is most useful for large perforations with friable tissue 5

• Mortality rates for perforated peptic ulcer remain high at 30%, with morbidity at 50%, making prompt diagnosis and intervention critical 1, 5

Helicobacter Pylori Testing

All patients with confirmed gastric ulcer must undergo H. pylori testing to identify the underlying cause and guide curative treatment 4

• Use non-invasive tests: urea breath test (sensitivity 88-95%, specificity 95-100%) or stool antigen test (sensitivity 94%, specificity 92%) 4

• Stop PPIs, antibiotics, and bismuth products for at least 2 weeks before testing to avoid false-negative results 4

Common Pitfalls to Avoid

• Do not delay imaging for laboratory results. CT should be obtained immediately when perforation is suspected 1, 2

• Do not rely on plain radiography alone. Negative X-rays do not exclude perforation given the 30-85% sensitivity range 1

• Do not dismiss the diagnosis based on minimal peritonitis. One-third of perforations present without typical peritoneal signs 1, 2

• Consider atypical appendicitis in the differential. Though rare, intestinal malrotation can cause left upper quadrant appendicitis mimicking gastric pathology 6