Gastroparesis Grading: 20% Retention at 4 Hours
A gastric retention of 20% at 4 hours represents mild gastroparesis (grade 1), falling just above the diagnostic threshold but below the moderate severity cutoff.
Diagnostic Thresholds Based on Test Meal Type
The classification depends on which standardized meal protocol was used:
Eggbeaters Meal Protocol (Most Common)
- Normal: <10% retention at 4 hours 1
- Mild gastroparesis (Grade 1): 11-20% retention at 4 hours 2
- Moderate gastroparesis (Grade 2): 21-35% retention at 4 hours 2
- Severe gastroparesis (Grade 3): >35% retention at 4 hours 2
With 20% retention using the Eggbeaters protocol, this patient has mild (grade 1) gastroparesis 2.
Real Eggs Meal Protocol
With 20% retention using the real eggs protocol, this would actually be normal gastric emptying 1.
Clinical Significance of Mild Gastroparesis
The degree of gastric emptying delay has important prognostic and therapeutic implications:
- Patients with mild gastroparesis (11-20% retention) are more likely to respond to standard medical therapy compared to those with moderate or severe delay 2
- Idiopathic gastroparesis patients with mild delay show significantly better response to medical management than those requiring gastric electrical stimulation 2
- Severe delay (>30% retention) correlates with increased emergency department visits and hospitalizations 3
- Moderate retention (>20% at 4 hours) predicted response to G-POEM in medically refractory cases 1
Important Caveats
The 2025 AGA guidelines emphasize that the diagnostic threshold is >10% retention at 4 hours for the Eggbeaters meal, but do not formally endorse a specific grading system 1. The mild/moderate/severe classification scheme (11-20%/21-35%/>35%) comes from research literature examining treatment outcomes 2.
Ensure the 4-hour measurement was obtained directly and not extrapolated from earlier time points 1. The test should have been performed without confounders like hyperglycemia, opioids, or GLP-1 receptor agonists 1.