Gastroparesis Scan

Understanding Gastroparesis Scan

Gastroparesis literally means "stomach paralysis"—a chronic condition where the stomach cannot empty normally in the absence of mechanical obstruction. The stomach's muscular contractions become weak, uncoordinated, or absent, preventing normal grinding and propulsion of food into the small intestine.

The hallmark symptoms—chronic nausea, vomiting, early satiety (feeling full quickly), abdominal bloating, and upper abdominal pain—significantly impair quality of life. Gastric emptying scintigraphy provides objective confirmation when these symptoms are present, distinguishing true gastroparesis from functional dyspepsia and other upper GI disorders.

How Gastroparesis Scan Works

The scan measures the stomach's ability to empty a standardized radiolabeled meal:

Standardized test meal (ANMS/ACG consensus protocol):

• Egg white sandwich with jam OR oatmeal
• Labeled with technetium-99m sulfur colloid (0.5-1 mCi)
• Radiotracer binds firmly to the food proteins
• Patient eats entire meal within 10 minutes

Imaging protocol (4-hour study):

• Time 0: Immediately after eating (100% gastric retention)
• Serial images: At 0, 30, 60, 120, and 240 minutes
• Anterior/posterior views: Correct for attenuation
• Geometric mean: Calculated for accuracy

Diagnostic criteria (at 2 hours):

• Normal: ＜10% retention
• Mild gastroparesis: 10-15% retention
• Moderate gastroparesis: 15-25% retention
• Severe gastroparesis: ＞25% retention

At 4 hours (confirmatory):

• Normal: ＜5% retention
• Abnormal: ＞10% retention

Clinical Patterns

Diabetic Gastroparesis

Diabetes is the most common identifiable cause:

Pathophysiology:

• Chronic hyperglycemia damages vagus nerve fibers
• Autonomic neuropathy impairs stomach motility
• Hyperglycemia itself slows gastric emptying (vicious cycle)
• Advanced glycation end products damage stomach muscle

Typical presentation:

• Long-standing diabetes (＞10 years)
• Other microvascular complications present
• Erratic blood glucose levels
• Difficulty matching insulin to meals

Prognosis:

• Generally progressive if diabetes poorly controlled
• Better outcomes with tight glycemic control
• May require insulin regimen adjustments

Post-Surgical Gastroparesis

After gastric operations:

• Fundoplication: Alters gastric compliance and fundic function
• Bariatric surgery: Sleeve gastrectomy or gastric bypass effects
• Gastrectomy: Reduced stomach capacity and innervation
• Vagotomy: Intentional or accidental nerve damage

Onset patterns:

• Immediate: Post-surgical inflammation or nerve damage
• Delayed: Scarring or adhesion formation

Idiopathic Gastroparesis

Unknown cause (30-40% of cases):

• More common in women (4:1 female predominance)
• Often follows viral gastroenteritis ("post-viral")
• May have autoimmune component
• Some patients have gradual insidious onset

Clinical features:

• Similar symptoms to diabetic gastroparesis
• Often younger patients
• May have better prognosis than diabetic form

Secondary Gastroparesis

Other medical conditions:

• Neurological: Parkinson's disease, MSA, stroke
• Connective tissue: Scleroderma, lupus, Sjogren's
• Metabolic: Hypothyroidism, uremia
• Medications: Opioids, GLP-1 agonists, tricyclics, anticholinergics

Clinical Applications

Diagnostic Confirmation

Confirming gastroparesis:

• Distinguishes from functional dyspepsia
• Identifies mechanical obstruction (if any)
• Provides objective diagnosis for symptoms
• Guides treatment selection

Severity assessment:

• Mild: May respond to diet and single medication
• Moderate: Requires combination therapy
• Severe: May need advanced therapies or nutritional support

Treatment Monitoring

Assessing response:

• Baseline study before initiating treatment
• Follow-up scan after 3-6 months of therapy
• Guides medication adjustments
• Determines need for advanced interventions

Treatment options monitored:

• Prokinetic medications (metoclopramide, erythromycin, domperidone)
• Dietary modifications
• Gastric electrical stimulation (Enterra therapy)
• Botulinum toxin injection into pylorus
• Pyloroplasty or gastrectomy (refractory cases)

Diabetes Management

Glycemic control implications:

• Gastroparesis causes unpredictable glucose absorption
• Makes insulin dosing challenging
• Can cause both hypoglycemia and hyperglycemia

Scan guides:

• Insulin regimen adjustments
• Timing of prandial insulin
• Need for continuous glucose monitoring
• Determining when to use long-acting vs. rapid-acting insulin

Evidence-Based Outcomes

Preparing for Your Scan

• Fasting: Nothing to eat or drink for 6-8 hours before the test
• Medications: Hold prokinetics, antiemetics, opioids for 48-72 hours
• Diabetic patients: Special glucose management instructions
• Planning: Bring reading material or entertainment (4-hour study)

Understanding Your Results

Frequently Asked Questions

Can gastroparesis be cured?

Complete cure is uncommon, but significant symptom improvement is possible. Post-viral gastroparesis may resolve completely in some patients. Diabetic gastroparesis is typically lifelong but can be well-managed. Treatment focuses on symptom control and nutritional support.

What is the diet for gastroparesis?

Eat small, frequent meals (6 per day). Choose low-fat, low-fiber foods. Liquid or pureed foods empty more easily. Examples: smoothies, yogurt, soup, applesauce, white rice, pasta, lean proteins. Avoid high-fat foods, raw fruits/vegetables, whole grains, carbonated drinks.

How does gastroparesis affect blood sugar?

Delayed stomach emptying makes carbohydrate absorption unpredictable and delayed. This causes blood sugar to rise later than expected after eating, making insulin dosing difficult. Patients may experience hypoglycemia when insulin acts before food absorbs, or hyperglycemia when food finally empties.

When is gastric electrical stimulation used?

Gastric electrical stimulation (Enterra therapy) is considered for severe, refractory gastroparesis that hasn't responded to medications and dietary changes. The device is surgically implanted and sends mild electrical impulses to the stomach, reducing nausea and vomiting in about 60-80% of patients.

References

1. American College of Gastroenterology. ACG Clinical Guidelines: Diagnosis and Management of Gastroparesis. 2024.
2. American Neurogastroenterology and Motility Society. ANMS Consensus Guidelines: Gastric Motor Function Testing. 2023.
3. Parkman HP, et al. Clinical Management of Gastroparesis. American Journal of Gastroenterology. 2024.

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Medical Disclaimer: This information is educational only. Always discuss findings with your healthcare provider for personalized medical advice.