Nausea & Vomiting

Definition

Nausea is a subjective sensation of the urge to vomit, while vomiting is the forceful expulsion of gastric contents through the mouth. These are common symptoms with a broad spectrum of causes ranging from benign self-limiting conditions to life-threatening disorders.

Epidemiology

• Very common symptom across all age groups
• Occurs in up to 50% of adults with acute gastrointestinal infections
• Pregnancy-related nausea affects ~70–80% of women in the first trimester
• Postoperative nausea and vomiting (PONV) affects 20–30% of surgical patients
• Incidence increases with certain medications, chemotherapy, and motion sickness susceptibility

Etiology

• Gastrointestinal: gastritis, gastroenteritis, peptic ulcer, obstruction, pancreatitis, hepatobiliary disorders
• Central: migraine, vestibular disorders, raised intracranial pressure, stroke, motion sickness
• Metabolic/endocrine: diabetic ketoacidosis, uremia, hypercalcemia, electrolyte imbalance, pregnancy (hyperemesis gravidarum)
• Medications: chemotherapy, opioids, antibiotics, digoxin
• Psychogenic: anxiety, stress, conditioned response

Pathophysiology

• Stimulation of the vomiting center in the medulla oblongata
• Inputs from chemoreceptor trigger zone (CTZ), vestibular system, cortex, and GI tract
• Neurotransmitters involved: serotonin (5-HT3), dopamine (D2), histamine (H1), acetylcholine (muscarinic), substance P (NK1 receptor)
• Integration leads to coordinated motor response: retroperistalsis, gastric relaxation, diaphragm and abdominal contraction
• Can be acute (minutes to hours) or chronic (weeks to months) depending on underlying cause