General MedicineTier 1Approach to a presentation

Undifferentiated presentations - vomiting

Red flags

GI mechanical

Obstruction (adhesions, hernia, malignancy, volvulus), gastroparesis, pyloric stenosis (infant)

GI inflammatory/infective

Metabolic/endocrine

DKA/HHS, uraemia, hypercalcaemia, Addisonian crisis, pregnancy (hyperemesis gravidarum)

Neurological

Raised ICP (mass, haemorrhage - early morning, projectile, without nausea), vestibular disease (vertigo-associated), migraine

Cardiac

Drug/toxin

Psychogenic

Timing (morning, post-prandial, projectile), content (bilious, faeculent, blood)
Associated pain, headache, neurological symptoms, cardiac symptoms
LMP/pregnancy status, medication and recreational drug use
Weight loss, early satiety (gastroparesis, malignancy)

Hydration status, abdominal exam (distension, tenderness, bowel sounds - absent/tinkling in obstruction)
Neurological exam, fundoscopy (papilloedema) if raised ICP suspected
Cardiovascular exam if cardiac cause considered

Treat the underlying cause; correct dehydration and electrolyte derangement (esp. hypokalaemia, metabolic alkalosis from vomiting itself)
Antiemetic choice by likely mechanism: ondansetron (broad first-line), metoclopramide (avoid in Parkinson's/young - dystonia risk), cyclizine (vestibular)
Obstruction - NG decompression, surgical/gastroenterology referral
DKA/HHS - fluid and insulin protocol
Hyperemesis gravidarum - IV fluids, thiamine (Wernicke's risk with prolonged vomiting), antiemetics safe in pregnancy (doxylamine/pyridoxine, ondansetron)

Vomiting without nausea, worse in the morning - think raised ICP, not gastroenteritis
Vomiting can be the presenting feature of inferior MI, especially in women/diabetics/elderly
Prolonged vomiting (any cause) risks Wernicke's encephalopathy if thiamine is not replaced before/with glucose
Cyclical/cannabinoid hyperemesis is often misdiagnosed as recurrent gastroenteritis for years

"Bilious, projectile, or morning-predominant vomiting redirects me away from a simple GI cause."
"I replace thiamine before glucose in anyone with prolonged vomiting and reduced intake."

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