What is the initial approach to investigating acute continuous nausea?

Investigation of Acute Continuous Nausea (3 Days)

For acute nausea lasting 3 days, begin with ondansetron 4-8 mg orally as empiric therapy while simultaneously ruling out life-threatening causes through targeted history, physical examination, and selective laboratory testing. 1

Initial Risk Stratification

Immediate Red Flags Requiring Urgent Evaluation

• Bilious vomiting is a surgical emergency until proven otherwise, requiring urgent fluoroscopy upper GI series 2
• Acute abdomen (severe abdominal pain, distention, absent bowel sounds) suggests bowel obstruction requiring immediate surgical consultation 1
• Severe headache with neurologic signs warrants head CT to exclude increased intracranial pressure or CNS pathology 1, 3
• Severe dehydration or metabolic acidosis requires hospitalization and IV fluid resuscitation 4

Targeted History Elements

Critical Questions to Ask

• Medication review: Opioids cause nausea in 10-50% of patients; chemotherapy and recent anesthesia are common culprits 5, 1
• Pregnancy status: Must be excluded in all women of childbearing age 4, 6
• Pattern recognition: Episodic vomiting with well periods suggests cyclic vomiting syndrome (CVS), though 3 days is within typical episode duration 5
• Associated symptoms: Abdominal pain location, fever, diarrhea, headache, vertigo 3, 7
• Recent exposures: Food ingestion timing (foodborne illness), travel, sick contacts (gastroenteritis) 7, 4

Physical Examination Priorities

• Abdominal examination: Distention, tenderness, bowel sounds to assess for obstruction 1
• Hydration status: Mucous membranes, skin turgor, orthostatic vital signs 4
• Neurologic examination: Focal deficits, papilledema if CNS cause suspected 3, 6

Initial Laboratory and Imaging Workup

First-Line Testing (Based on Clinical Suspicion)

• Basic metabolic panel: Identifies electrolyte abnormalities, renal dysfunction, hyperglycemia 4, 6
• Pregnancy test: Mandatory in reproductive-age women 7, 4
• Complete blood count: Evaluates for infection, anemia 4
• Urinalysis: Detects urinary tract infection, ketones 4

Additional Testing When Indicated

• Lipase/amylase: If epigastric pain suggests pancreatitis 4
• Thyroid-stimulating hormone: If endocrine cause suspected 4
• Abdominal radiography: First-line imaging for suspected obstruction 6
• Abdominal CT: For acute abdomen or when plain films inconclusive 4, 6
• Head CT: Only if neurologic symptoms present 4

Empiric Management During Evaluation

Pharmacologic Therapy

• Ondansetron 4-8 mg orally/sublingual is the preferred initial antiemetic for acute nausea 1, 8
• Combination therapy with haloperidol and benzodiazepine for refractory vomiting 1
• Avoid empiric antiemetics if acute abdomen suspected until surgical evaluation complete 6

Supportive Care

• Oral rehydration: Small, frequent sips of electrolyte-rich fluids if tolerating oral intake 1
• IV fluid therapy: Normal saline or lactated Ringer's for patients unable to tolerate oral intake 1

Common Pitfalls to Avoid

• Missing pregnancy: Always test before imaging or prescribing teratogenic medications 7, 4
• Overlooking medication causes: Opioids, chemotherapy, and antibiotics are frequently implicated 5, 1
• Misinterpreting CVS: Hot water bathing behavior is not specific to cannabinoid hyperemesis syndrome and occurs in 48% of CVS patients who don't use cannabis 5
• Premature extensive workup: Most acute nausea (≤7 days) is self-limited gastroenteritis requiring only symptomatic treatment unless alarm features present 3, 7, 4

When to Pursue Further Evaluation

If symptoms persist beyond 7 days or worsen despite treatment, transition to chronic nausea evaluation including:

• Upper endoscopy: To exclude mechanical obstruction, peptic ulcer disease, malignancy 1
• Gastric emptying scintigraphy: If gastroparesis suspected (requires 2-4 hour study) 1, 2
• Consider CVS: If episodic pattern emerges with stereotypical episodes lasting <7 days separated by well periods 5, 2