What is the best course of treatment for a patient presenting to the Emergency Room (ER) with hyperemesis gravidarum?

Management of Hyperemesis Gravidarum in the Emergency Room

The best course of treatment for a patient presenting to the ER with hyperemesis gravidarum is immediate rehydration, correction of electrolyte abnormalities, thiamine supplementation, and antiemetic therapy with medications such as ondansetron. 1, 2

Initial Assessment and Stabilization

• Diagnose hyperemesis gravidarum based on persistent vomiting, weight loss ≥5% of pre-pregnancy weight, dehydration, and ketonuria 2
• Assess severity using the Pregnancy-Unique Quantification of Emesis (PUQE) score to guide management decisions 2
• Evaluate for signs of dehydration, electrolyte abnormalities, and ketonuria 2
• Check liver function tests, as approximately 50% of patients will have abnormal AST and ALT, though rarely >1,000 U/L 1

First-Line Management

• Immediate intravenous fluid resuscitation to correct dehydration, which often improves liver chemistry abnormalities 1, 2
• Electrolyte replacement with particular attention to potassium and magnesium levels 1, 2
• Thiamine supplementation (vitamin B1) to prevent Wernicke's encephalopathy, a serious neurological complication 1, 3
• Antiemetic therapy with medications that have favorable pregnancy safety profiles 1, 2

Antiemetic Medication Options

1. First-line antiemetics:

   • Ondansetron (5-HT3 antagonist) - specifically mentioned as having favorable pregnancy safety 1
   • Metoclopramide (dopamine antagonist) 1, 3
   • Promethazine (H1-receptor antagonist) 1, 3

2. For patients not responding to first-line therapy:

   • Combination of doxylamine and pyridoxine (vitamin B6) 4
   • Consider corticosteroids for severe, refractory cases 2, 5

Special Considerations

• Monitor for QT interval prolongation, especially with ondansetron, particularly in patients with electrolyte abnormalities 1
• For patients with hyperemesis gravidarum and Bartter syndrome, aim for plasma potassium levels ≥3.0 mmol/L 1
• Be vigilant for thromboembolism risk due to dehydration and immobility; consider thromboprophylaxis 6
• Persistent liver chemistry abnormalities despite symptom resolution should prompt investigation for another etiology 1

Refractory Cases

• For patients not responding to standard antiemetics, consider alternative pharmacotherapeutics:
  • Mirtazapine - has antiemetic, anxiolytic, and appetite-stimulating effects 4, 5
  • Olanzapine or gabapentin may be considered in severe cases 2, 5
  • Intravenous corticosteroids when other treatments fail 2, 5

Nutritional Support

• Once vomiting is controlled, gradually reintroduce oral intake with small, frequent, bland meals 2
• For prolonged cases with ongoing weight loss despite maximal medical therapy, consider enteral or parenteral nutrition 5

Discharge Planning and Follow-up

• Ensure ability to tolerate oral intake and medications before discharge 5
• Arrange close follow-up for monitoring of symptoms, weight, and electrolytes 2
• Educate patients about the high recurrence risk (40-92%) in subsequent pregnancies 1
• Inform patients that hyperemesis gravidarum typically resolves by week 16-20 in most cases, though 10% may experience symptoms throughout pregnancy 2

Complications to Monitor

• Wernicke's encephalopathy due to thiamine deficiency 3, 7
• Electrolyte imbalances, particularly hypokalemia 1
• Thromboembolism, including deep vein thrombosis and pulmonary embolism 6, 7
• Low birth weight and premature delivery 1, 2