What are the diagnostic criteria and treatment options for gastroparesis?

Gastroparesis Diagnosis

Gastroparesis is diagnosed by demonstrating delayed gastric emptying on a properly performed 4-hour gastric emptying scintigraphy study, combined with characteristic symptoms (nausea, vomiting, postprandial fullness, early satiety), after excluding mechanical obstruction via upper endoscopy. 1

Diagnostic Criteria

The diagnosis requires three essential components 1:

• Appropriate symptoms: Nausea, vomiting, postprandial abdominal fullness, early satiety, bloating, and upper abdominal pain 1
• Documented delayed gastric emptying on objective testing 1
• Absence of mechanical obstruction in the stomach or small intestine 1

Critical Pitfall: Symptoms Alone Are Inadequate

Symptoms correlate poorly with the degree of gastric emptying delay and cannot be used alone for diagnosis 2, 3. Objective testing is mandatory 2.

Diagnostic Testing Algorithm

Step 1: Rule Out Mechanical Obstruction

• Upper endoscopy (EGD) must be performed first to exclude structural causes including mechanical obstruction, inflammatory conditions, or malignancy before proceeding with functional testing 2, 3

Step 2: Gastric Emptying Scintigraphy (Gold Standard)

Proper technique is critical 1, 2:

• Test duration: Minimum 2 hours, but 4-hour testing provides higher diagnostic yield and accuracy and should be the standard 1, 2
• Meal preparation: The radioisotope (99mTc sulfur colloid) must be cooked into the solid portion of the meal—typically a standardized low-fat egg white sandwich with jam and toast 1, 2
• Pre-test preparation 2:
  • Withdraw medications affecting gastric emptying (prokinetics, opioids, anticholinergics) for 48-72 hours 2
  • Avoid smoking on test day 2
  • Monitor and control blood glucose—hyperglycemia itself slows gastric emptying and can cause false positive results 2

Common pitfall: Tests shorter than 2 hours are inaccurate and should not be used 1, 2.

Step 3: Alternative or Adjunctive Testing

If scintigraphy is unavailable or results are inconclusive 1, 2:

• 13C-octanoate breath testing: Non-radioactive alternative that correlates well with scintigraphy 1, 2
• Antroduodenal manometry: Provides information about gastric-duodenal motor coordination and can differentiate neuropathic from myopathic disorders 1, 2, 3
  • Useful when gastric emptying is normal but symptoms persist 2
  • Shows decreased antral contractility and abnormal migrating motor complexes in gastroparesis 1

Step 4: Additional Laboratory Evaluation

• Complete blood count, comprehensive metabolic panel, liver function tests, thyroid-stimulating hormone to exclude metabolic causes 3
• In diabetic patients: assess glycemic control as hyperglycemia causes gastric dysmotility 2, 3
• In patients with persistent vomiting >2-3 weeks: check thiamin levels to prevent neurological complications 2

Treatment Options

Dietary Management (First-Line)

• Small, frequent meals with lower fat and fiber content 2
• Adequate hydration: Maintain ≥1.5 L fluids/day 2
• Eating behavior modifications: Small bites, thorough chewing, slow eating (≥15 minutes per meal), separate liquids from solids 2

Pharmacologic Treatment

Prokinetic Agents

• Metoclopramide: FDA-approved for diabetic gastroparesis 4, 5

  • Dosing: 10 mg orally or IV (slowly over 1-2 minutes) 4
  • For severe symptoms: start with IV/IM administration, transition to oral when symptoms improve 4
  • Renal dosing: Reduce dose by 50% if creatinine clearance <40 mL/min 4
  • Major caveat: Risk of tardive dyskinesia and extrapyramidal symptoms, especially in elderly and pediatric patients 4

• Other prokinetics (off-label): Domperidone, erythromycin (short-term use) 5

Antiemetic Agents

Multiple options should be considered for nausea and vomiting 1, 2:

• Phenothiazines 1
• 5-HT3 antagonists (ondansetron) 1
• NK-1 receptor antagonists (aprepitant) 1

Pain Management

• Neuromodulators (tricyclic antidepressants, SNRIs) can be considered for gastroparesis-associated abdominal pain 1
• Avoid opioids: They worsen gastric emptying and symptoms 1, 2

Nutritional Support

• If oral intake inadequate: enteral nutrition via jejunostomy tube 5
• Parenteral nutrition rarely required 5

Interventional Therapies for Refractory Cases

Classify severity before considering interventions 1:

• Gastric electrical stimulation (GES): Consider for patients with refractory/intractable nausea and vomiting who have failed standard therapy and are not on opioids 1, 2

  • May reduce weekly vomiting frequency and need for nutritional supplementation 5

• Gastric per-oral endoscopic myotomy (G-POEM): Consider for select patients with severe gastric emptying delay using a multidisciplinary team approach at centers of excellence 1, 2

• Second-line options: Venting gastrostomy or feeding jejunostomy 5

• Avoid: Intrapyloric botulinum toxin injection (ineffective in randomized controlled trials) 5

• Rarely indicated: Partial gastrectomy and pyloroplasty—only for carefully selected patients 5

Disease Classification

After diagnosis, classify patients as mild, moderate, or severe based on symptoms and gastric emptying study results to guide treatment intensity 1.

Common Etiologies

• Diabetic: Most common in long-standing type 1 diabetes with other complications (20-40% prevalence) 1
• Idiopathic: May occur after viral infection; overlaps with functional dyspepsia 1
• Postsurgical: Following gastric or vagal surgery 1