What is the complete differential diagnosis of nausea and vomiting?

Complete Differential Diagnosis of Nausea and Vomiting

Systematic Categorization by Organ System

The differential diagnosis for nausea and vomiting must be systematically organized by temporal pattern (acute ≤7 days vs. chronic ≥4 weeks) and then by organ system, including gastrointestinal, neurologic, metabolic/endocrine, medication-related, and psychogenic causes. 1

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I. Gastrointestinal Causes

Acute Gastrointestinal Conditions

• Bowel obstruction - life-threatening, presents with abdominal distention, absent bowel sounds, and colicky pain 1
• Gastroenteritis and viral syndromes - most common cause of acute symptoms, typically self-limiting 2
• Foodborne illness - acute onset related to recent food ingestion 2
• Peptic ulcer disease - can be excluded with upper endoscopy 1

Chronic Gastrointestinal Conditions

• Gastroparesis - delayed gastric emptying affecting 20-40% of diabetic patients and 25-40% of functional dyspepsia patients, diagnosed by gastric emptying scintigraphy performed for at least 2 hours (4-hour testing provides higher diagnostic yield) 3, 1
• Cyclic vomiting syndrome (CVS) - prevalence ~2% in US adults, characterized by stereotypical episodes of acute-onset vomiting lasting <7 days, with at least 3 discrete episodes in the previous year and 2 episodes in the past 6 months, occurring at least 1 week apart, with absence of nausea and vomiting between episodes 4, 1
• Cannabinoid hyperemesis syndrome (CHS) - paradoxical cannabis-associated vomiting, patients report need for hot water bathing to alleviate symptoms (44% vs 19% in chronic nausea and vomiting syndrome) 4
• Functional dyspepsia - defined by Rome IV criteria as bothersome epigastric pain, burning, postprandial fullness, or early satiation without structural disease 3
• Gastric neuromuscular disorders - including gastric dysrhythmias and abnormalities of gastric accommodation 5
• Mechanical obstruction - must be ruled out with upper endoscopy before diagnosing functional or motility disorders 3
• Malignancy - excluded by upper endoscopy 1

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II. Neurologic Causes

• Central nervous system tumors - cause nausea through increased intracranial pressure 1
• Increased intracranial pressure - typically causes other neurologic signs 1, 6
• Acute migraine headaches - common cause of acute nausea and vomiting 2
• Vestibular disturbances - peripheral causes of acute symptoms 2

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III. Metabolic and Endocrine Causes

• Pregnancy - most common endocrinologic cause, must be considered in any woman of childbearing age 6
• Diabetic complications - hyperglycemia itself can cause gastric dysmotility 3
• Numerous metabolic abnormalities - including electrolyte disturbances, uremia, and hepatic dysfunction 6
• Thiamin deficiency - evaluate in patients with persistent vomiting >2-3 weeks to prevent neurological complications 3

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IV. Medication and Toxin-Related Causes

• Opioid-induced nausea - occurs in 10-50% of patients receiving opioids; opioids worsen gastric emptying and should be avoided in gastroparesis patients 1
• Chemotherapy-induced nausea and vomiting - managed with antiemetic therapy 1
• Medication adverse effects - must be considered early in evaluation, resolved by removing offending agent 2, 6
• Cannabis use - associated with CVS, CHS, and cannabinoid withdrawal syndrome (CWS prevalence 47% in cannabis users) 4
• Cannabinoid withdrawal syndrome (CWS) - occurs commonly on cessation of heavy and prolonged cannabis use, pooled prevalence 47% in systematic review of 23,518 participants 4

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V. Psychiatric and Psychogenic Causes

• Psychiatric diagnoses - numerous conditions can manifest with nausea and vomiting 6
• Psychogenic disorders - should be considered when organic causes excluded 1, 7
• Psychiatric comorbidity - associated with CVS, along with younger age and tobacco use 4

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VI. Infectious Causes

• Gastrointestinal infections - most common cause of acute nausea and vomiting, typically self-limiting and require minimal intervention 6, 8

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VII. Special Patterns and Syndromes

Coalescent CVS

• Severe CVS progression - characterized by increased episodic length and frequency over years, with progressively few asymptomatic days, culminating in daily nausea and vomiting in some patients 4
• Diagnostic challenge - patients lose prototypical "well periods" between episodes and meet Rome IV criteria for chronic nausea vomiting syndrome, but careful history reveals years of episodic pattern before coalescent phase 4

CVS Severity Classification

• Mild CVS - <4 episodes/year, each lasting <2 days, without ED visits or hospitalizations 4
• Moderate-severe CVS - ≥4 episodes/year, each lasting >2 days, requiring ED visits or hospitalizations 4

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Critical Diagnostic Pitfalls to Avoid

• Relying solely on symptoms - symptoms correlate poorly with degree of gastric emptying delay 3
• Failure to control blood glucose during testing - hyperglycemia can slow gastric emptying and lead to false positive results 3
• Not accounting for medications affecting gastric emptying - prokinetics, opioids, and anticholinergics can lead to inaccurate results 3
• Shorter gastric emptying test durations - <2 hours are inaccurate for determining gastroparesis 3
• Missing cannabis use history - critical for distinguishing CHS from CVS, as cannabis use augments hot water bathing behavior 4
• Overlooking eating behaviors - eating too quickly, insufficient chewing, and overeating can cause postprandial vomiting 3