Definition of Persistent Vomiting
Persistent vomiting is defined as vomiting that lasts 14-29 days, distinguishing it from acute vomiting (<7 days), prolonged vomiting (7-13 days), and chronic vomiting (≥30 days). 1
Clinical Classification of Vomiting by Duration
The Infectious Diseases Society of America provides a clear temporal classification system for vomiting:
- Acute vomiting: Lasts less than 7 days
- Prolonged vomiting: Lasts 7-13 days
- Persistent vomiting: Lasts 14-29 days
- Chronic vomiting: Lasts 30 days or longer
Lack of Consensus in Medical Literature
Despite the IDSA definition, it's important to note that there is significant inconsistency in how persistent vomiting is defined across medical literature:
- A 2017 systematic review found no consensus definition among authors 2
- Some studies define persistent vomiting based on:
- Number of episodes (e.g., ≥2 episodes 15 minutes apart, >3 episodes in 12 hours)
- Duration (days or weeks)
- Inability to retain food/fluids (e.g., vomiting of all foods and fluids in 24 hours)
Clinical Implications
The definition of persistent vomiting has important clinical implications:
- Diagnostic approach: Persistent vomiting (14-29 days) warrants a more thorough evaluation than acute vomiting, including consideration of endoscopic evaluation 3
- Risk assessment: Persistent vomiting increases risk for complications including:
- Dehydration and electrolyte abnormalities
- Nutritional deficiencies (consider thiamin supplementation if vomiting persists >2-3 weeks) 3
- Metabolic alkalosis
Management Considerations
When managing persistent vomiting:
- Monitor hydration status and electrolytes closely 3
- Evaluate for red flag symptoms that require urgent intervention:
- Bilious or bloody vomiting
- Signs of increased intracranial pressure
- Severe dehydration
- Altered mental status 4
- Consider antiemetic therapy with ondansetron (0.15-0.2 mg/kg) for symptomatic relief 4
- Investigate underlying causes based on patient age and associated symptoms
Conclusion
While the Infectious Diseases Society of America clearly defines persistent vomiting as vomiting lasting 14-29 days, clinicians should be aware that this term is used inconsistently in medical literature. The lack of standardization in terminology highlights the need for clear communication when discussing this symptom in clinical settings.