When is a gastric emptying study recommended?

When to Recommend a Gastric Emptying Study

A gastric emptying study is recommended for patients with symptoms suggestive of gastroparesis (nausea, vomiting, early satiety, postprandial fullness, bloating) when other causes have been ruled out through appropriate evaluation, particularly in patients with risk factors such as diabetes, prior gastric surgery, or idiopathic causes. 1

Indications for Gastric Emptying Studies

Primary Indications

• Persistent upper GI symptoms including:
  • Nausea and vomiting
  • Postprandial fullness
  • Early satiety
  • Bloating
  • Abdominal pain 1

Clinical Scenarios Warranting Testing

• Patients with diabetes and persistent GI symptoms 1
• Post-surgical patients with upper GI symptoms 2
• Patients with unexplained (idiopathic) upper GI symptoms 1
• Patients with symptoms refractory to empiric treatment 1
• Patients with suspected gastroparesis when symptoms and gastric emptying delay don't correlate well 1

Diagnostic Approach

Pre-Test Considerations

• Rule out structural causes first:

  • Upper endoscopy to exclude mechanical obstruction or mucosal disease 1
  • Selective imaging when clinically indicated 1

• Preparation for accurate testing:

  • Medications that affect gastric emptying should be withdrawn 48-72 hours before the test 1
  • Smoking should be avoided on the test day 1
  • Blood glucose should be monitored and ideally maintained between 4-10 mmol/L during the test 1

Testing Methodology

• Scintigraphy (gold standard):

  • 4-hour solid-phase gastric emptying study is preferred 1
  • Standard low-fat, egg white meal labeled with 99mTc sulfur colloid 1
  • Shorter test durations (2 hours or less) are inaccurate for determining gastroparesis 1

• Alternative methods when scintigraphy is unavailable:

  • 13C-labeled breath tests (acetate or octanoic acid) 1
  • Wireless motility capsule (research and specialized centers) 1

Interpretation and Classification

• Normal gastric emptying: <10% retention at 4 hours 1
• Mild delay: 10-15% retention at 4 hours 1
• Moderate delay: 15-35% retention at 4 hours 1
• Severe delay: >35% retention at 4 hours 1

Important Clinical Considerations

Symptom-Test Correlation

• Symptoms often do not correlate well with the degree of gastric emptying delay 1, 3
• A meta-analysis showed significant but modest associations between optimally measured delayed gastric emptying and symptoms including nausea (OR 1.6), vomiting (OR 2.0), abdominal pain (OR 1.5), and early satiety/fullness (OR 1.8) 3

Testing Pitfalls to Avoid

• Inadequate methodology:

  • Failure to perform 4-hour studies (shorter studies miss many cases) 1
  • Not controlling blood glucose during testing 1
  • Not withdrawing medications that affect gastric motility 1

• Limited testing scope:

  • Consider testing both solid and liquid emptying as liquid emptying may be abnormal when solid emptying is normal in up to 33% of patients 4
  • Failure to recognize that rapid gastric emptying can also cause similar symptoms 5

Special Populations

• Diabetic patients:

  • Acute hyperglycemia can delay gastric emptying and increase GI symptom perception 1
  • Hypoglycemia can accelerate gastric emptying 1
  • Proper glycemic control is essential during testing 1

• Patients with overlapping functional disorders:

  • Gastroparesis symptoms overlap significantly with functional dyspepsia 1
  • Consider testing in patients with functional dyspepsia not responding to standard therapy 1

By following these guidelines, clinicians can appropriately select patients for gastric emptying studies and ensure accurate testing methodology to guide effective management of gastroparesis and related disorders.