What is the workup for vomiting after eating?

Diagnostic Workup for Vomiting After Eating

The diagnostic workup for postprandial vomiting should begin with assessment for mechanical obstruction, gastroparesis, and functional disorders, as these represent the most common causes requiring specific interventions. 1

Initial Assessment

• Obtain a detailed history focusing on timing of vomiting in relation to meals, character of vomitus, associated symptoms, and duration of symptoms 1
• Evaluate for risk factors such as diabetes, recent surgery, medication use, and cannabis use, which are associated with increased risk of postprandial vomiting 1
• Physical examination should focus on hydration status, abdominal tenderness, and presence of distension 1
• Look for "red flag" signs including bilious or bloody vomiting, altered mental status, toxic appearance, severe dehydration, or bent-over posture 2

Laboratory Evaluation

• Complete blood count, electrolytes, glucose, liver function tests, and lipase to rule out metabolic causes and assess for complications 1
• In patients with persistent vomiting >2-3 weeks, evaluate thiamin levels to prevent neurological complications 1
• In dehydrated patients or those with red flag signs, check serum electrolytes, blood gases, and renal and liver functions 2
• Monitor hydration status and blood electrolytes, especially with persistent vomiting 3

Diagnostic Testing

• Upper endoscopy (esophagogastroduodenoscopy) to rule out mechanical obstruction, which is essential before diagnosing a functional or motility disorder 1
• Gastric emptying scintigraphy is the gold standard test for diagnosing gastroparesis, and should be performed for at least 2 hours, with 4-hour testing providing higher diagnostic yield 1
• The radioisotope must be cooked into the solid portion of the meal for accurate results 1
• Medications that influence gastric emptying should be withdrawn for 48-72 hours prior to testing 1
• Breath testing using non-radioactive substances can be used as an alternative to scintigraphy 1
• Radiological studies may be required to diagnose surgical causes of vomiting 2

Special Considerations

• In diabetic patients, check glycemic control as hyperglycemia itself can cause gastric dysmotility 1
• In patients with significant weight loss or malnutrition, nutritional assessment is essential 1
• For cyclic vomiting syndrome, consider gastroenterology consultation for specialized testing 3
• For patients with bariatric surgery history, evaluate for surgical complications or inappropriate eating behaviors 3

Management Approach While Awaiting Diagnosis

• Maintain adequate hydration (≥1.5 L fluids/day) 3
• Take small bites, chew thoroughly and eat slowly with a meal duration of ≥15 minutes 3
• Separate liquids from solids; abstain from drinking 15 min before and 30 min after meals 3
• Space meals at intervals of ≥2-4 hours 3
• For persistent vomiting, ondansetron may be considered (4-8 mg PO) 4
• Monitor for signs of dehydration and electrolyte imbalances 3

Common Pitfalls to Avoid

• Relying solely on symptoms for diagnosis is inadequate as symptoms correlate poorly with the degree of gastric emptying delay 1
• Failure to control blood glucose during testing can lead to false positive results for gastroparesis 1
• Not accounting for medications that can affect gastric emptying (prokinetics, opioids, anticholinergics) can lead to inaccurate results 1
• Administering antiemetics like chlorpromazine may cause drowsiness that interferes with oral rehydration therapy 5
• Overlooking life-threatening causes of vomiting, especially in infants and children 2

Remember that vomiting after eating may be a symptom of various conditions ranging from simple gastroenteritis to more serious conditions requiring prompt intervention. A systematic approach to diagnosis is essential for appropriate management and improved outcomes.