What is the diagnostic approach for Gastroparesis?

Diagnostic Approach for Gastroparesis

The diagnosis of gastroparesis requires the presence of characteristic symptoms, delayed gastric emptying on a 4-hour gastric emptying scintigraphy, and the absence of mechanical obstruction. 1

Key Symptoms to Evaluate

• Cardinal symptoms:

  • Nausea and vomiting
  • Postprandial fullness
  • Early satiety
  • Bloating
  • Abdominal pain/discomfort 2, 1

• Differential diagnosis considerations:

  • Distinguish vomiting from regurgitation, rumination, and bulimia
  • Rule out conditions that mimic gastroparesis (cyclic vomiting syndrome, cannabinoid hyperemesis syndrome, functional dyspepsia) 2, 1

Diagnostic Algorithm

Step 1: Initial Evaluation

• Document symptom characteristics, duration, frequency, and severity
• Identify risk factors:
  • Diabetes (especially long-standing type 1 diabetes)
  • Prior gastric surgery
  • Medications (opioids, GLP-1 agonists)
  • Post-viral illness 2, 1

Step 2: Rule Out Mechanical Obstruction

• Upper endoscopy is mandatory before proceeding with gastric emptying studies
  • Rules out mechanical obstruction, peptic ulcer disease, and other structural causes 2, 1

Step 3: Gastric Emptying Testing

• Gold standard: 4-hour gastric emptying scintigraphy

  • Radiolabeled solid meal (typically 99mTc sulfur colloid-labeled egg sandwich)
  • Imaging at 0,1,2, and 4 hours
  • Critical: Test must be performed for 4 hours (shorter durations are inaccurate) 2, 1

• Interpretation criteria:

  Severity	Retention at 4 hours
  Normal	<10%
  Mild	10-15%
  Moderate	15-35%
  Severe	>35%
  1

Step 4: Alternative Diagnostic Methods

• 13C-labeled breath tests (acetate or octanoic acid)

  • Non-radioactive alternative
  • Measures 13C in breath samples to indirectly determine gastric emptying 2, 1

• Wireless motility capsule

  • Measures pH, pressure, and temperature changes
  • Can assess whole gut transit 1

• Antroduodenal manometry (specialized centers)

  • Provides information about gastric and duodenal motor function
  • Can differentiate between neuropathic and myopathic motility disorders
  • Helps diagnose unexpected small bowel obstruction or rumination syndrome 2, 1

Common Pitfalls and Caveats

1. Improper gastric emptying methodology

   • Verify proper test protocol (4-hour duration is essential)
   • Ensure radioisotope is cooked into solid portion of meal 2, 1

2. Poor symptom-emptying correlation

   • Symptoms may not correlate well with degree of emptying delay
   • Consider additional factors like impaired fundic accommodation, antral hypomotility, and visceral hypersensitivity 1, 3

3. Hyperglycemia effect

   • Acute hyperglycemia can delay gastric emptying
   • Ensure glucose levels are controlled during testing in diabetic patients 2, 1

4. Medication interference

   • Discontinue medications that affect gastric emptying (prokinetics, opioids, anticholinergics, GLP-1 agonists) before testing 2, 1

5. Overlooking functional dyspepsia overlap

   • Significant symptom overlap exists between gastroparesis and functional dyspepsia
   • Idiopathic gastroparesis may be one cause of functional dyspepsia 2, 3

By following this systematic diagnostic approach, clinicians can accurately diagnose gastroparesis and classify its severity, which guides appropriate management strategies.