Investigation Required for Acute Abdomen and Reflux Oesophagitis
For a patient presenting with acute abdomen, immediate CT abdomen and pelvis with IV contrast is the priority investigation to rule out surgical emergencies, followed by upper endoscopy with biopsies once acute pathology is excluded to evaluate the reflux oesophagitis.
Acute Abdomen Investigation
The acute abdomen component takes precedence as it may represent a life-threatening surgical emergency requiring immediate intervention. CT abdomen and pelvis with IV contrast is the initial imaging modality of choice 1. This will identify:
- Perforated peptic ulcer (extraluminal gas in 97%, focal wall defect in 84%, wall thickening in 72%)
- Gastroduodenal perforation with free air
- Active bleeding from peptic ulcers (hyperdense blood products or contrast extravasation)
- Gastric outlet obstruction
- Alternative surgical emergencies (appendicitis, cholecystitis, bowel obstruction)
Key CT Findings to Evaluate:
- Gastric/duodenal wall thickening (≥5mm suggests inflammation/ulceration)
- Focal wall defects or ulcer craters (positive likelihood ratio 36.83 for perforation)
- Extraluminal gas (97% sensitive for perforation)
- Fluid or fat stranding along gastroduodenal region
- Mucosal hyperenhancement indicating active inflammation
Reflux Oesophagitis Investigation
Once acute surgical pathology is excluded and the patient is stabilized, proceed with evaluation of reflux oesophagitis:
1. Upper Endoscopy with Biopsies (Primary Investigation)
Endoscopy should be performed with systematic evaluation 2:
- Grade erosive esophagitis using Los Angeles classification
- Assess diaphragmatic hiatus (Hill grade of flap valve)
- Measure axial hiatus hernia length
- Inspect for Barrett's esophagus (Prague classification)
- Obtain at least 5 esophageal biopsies from any abnormal areas or normal-appearing mucosa 3
Critical: Biopsies must evaluate for:
- Eosinophilic esophagitis (requires ≥5 samples from normal mucosa) 3
- Barrett's metaplasia
- Dysplasia or malignancy
- Reflux-associated histologic changes (T-cell infiltration, basal cell hyperplasia, intercellular space widening) 4
2. When to Perform Ambulatory pH Monitoring
If endoscopy is normal or shows only mild changes (LA grade A or less), proceed with 96-hour wireless pH monitoring OFF PPI therapy 2. This is indicated when:
- Symptoms persist despite twice-daily PPI therapy
- Need to confirm GERD before long-term PPI therapy
- Considering surgical intervention
- Evaluating atypical or extraesophageal symptoms
Withhold PPIs for at least 7 days before pH monitoring 3 to avoid false-negative results.
3. Esophageal Manometry
Perform high-resolution manometry if 3:
- Normal endoscopy AND normal pH monitoring but persistent symptoms
- Pre-operative evaluation before anti-reflux surgery
- Suspicion for achalasia or esophageal spasm masquerading as GERD
Important Clinical Caveats
Alarm Features Requiring Urgent Endoscopy:
- Weight loss, dysphagia, epigastric mass have the best performance for identifying malignancy 3
- Troublesome dysphagia mandates endoscopy with biopsies (Grade B recommendation) 3
- Anemia, vomiting combined with dyspeptic symptoms 5
Common Pitfalls to Avoid:
Do NOT assume chronic reflux symptoms = benign disease - always perform endoscopy with biopsies to exclude malignancy 5
Do NOT miss eosinophilic esophagitis - requires multiple biopsies (≥5) even from normal-appearing mucosa in patients with dysphagia 6, 3
Do NOT perform endoscopy while on PPIs if possible - ideally withdraw PPIs for 3 weeks before endoscopy for accurate diagnosis of eosinophilic esophagitis 6, though this may not be practical in acute settings
Do NOT rely on symptom response to PPIs as diagnostic confirmation - symptom improvement may result from non-acid suppression mechanisms 7
Algorithmic Approach
Step 1: CT abdomen/pelvis with IV contrast → Rule out surgical emergency
Step 2: If no surgical emergency → Upper endoscopy with ≥5 biopsies
Step 3: If endoscopy shows LA grade B or greater esophagitis OR Barrett's ≥3cm → Diagnosis confirmed, initiate treatment
Step 4: If endoscopy normal/minimal changes → 96-hour wireless pH monitoring (off PPIs for 7 days)
Step 5: If pH monitoring normal but symptoms persist → High-resolution manometry to exclude motility disorders
This systematic approach prioritizes life-threatening conditions while ensuring comprehensive evaluation of reflux disease and its complications, avoiding misdiagnosis of alternative conditions that may masquerade as GERD.