What is the initial approach to managing hyperemesis?

Initial Management of Hyperemesis Gravidarum

Begin with immediate intravenous fluid resuscitation to correct dehydration, thiamine supplementation to prevent Wernicke's encephalopathy, and electrolyte replacement—this stabilization often improves symptoms and laboratory abnormalities before any antiemetic therapy is initiated. 1, 2

Immediate Stabilization (First Priority)

• Administer IV fluids aggressively to correct dehydration, which frequently resolves associated liver enzyme abnormalities and improves overall clinical status 1, 2
• Start thiamine 100 mg daily for minimum 7 days, then 50 mg daily maintenance until adequate oral intake is established—this prevents Wernicke encephalopathy, a devastating neurological complication 1, 2
• If vomiting persists or patient cannot tolerate oral intake, switch to IV thiamine 200-300 mg daily 2
• Replace electrolytes with particular attention to potassium and magnesium levels, as these are commonly depleted 1, 2

Initial Assessment

• Check electrolyte panel, liver function tests, and urinalysis for ketonuria 1, 2
• Assess severity using the Pregnancy-Unique Quantification of Emesis (PUQE) score 1, 2
• Perform abdominal ultrasonography to detect multiple or molar pregnancies and rule out hepatobiliary causes 2
• Evaluate for weight loss ≥5% of pre-pregnancy weight and signs of dehydration 1

Stepwise Pharmacologic Management

First-Line Antiemetic

• Doxylamine-pyridoxine combination is the preferred initial antiemetic, safe throughout pregnancy and breastfeeding 2
• This should be started after initial stabilization with fluids and thiamine 2

Second-Line Antiemetic (If First-Line Fails)

• Metoclopramide is the preferred second-line agent when first-line antihistamines fail, with similar efficacy to promethazine but fewer side effects 2
• Promethazine is acceptable but causes significantly more drowsiness, dizziness, dystonia, and treatment discontinuations compared to metoclopramide 2
• Ondansetron should be reserved as second-line therapy due to concerns about congenital heart defects when used before 10 weeks gestation, though recent data suggest the risk is low 2
• Use ondansetron on a case-by-case basis before 10 weeks of pregnancy 2
• Monitor for QT interval prolongation with ondansetron, especially in patients with electrolyte abnormalities 1

Third-Line for Refractory Cases

• Methylprednisolone should be reserved as last resort for severe hyperemesis gravidarum that fails other therapies 2
• Use caution in the first trimester due to slight increased risk of cleft palate when given before 10 weeks gestation 2
• Olanzapine has shown value for preventing delayed and refractory emesis and nausea 3, 1
• Use olanzapine with caution in elderly patients due to risks of dementia-related psychosis, type II diabetes, and hyperglycemia 3, 1

Dosing Strategy

• Consider around-the-clock administration of antiemetics rather than PRN (as-needed) dosing to prevent emesis 3, 1
• The oral route may not be feasible due to ongoing vomiting; rectal or IV therapy is often required 3, 1
• For breakthrough emesis, give an additional agent from a different drug class rather than increasing the dose of the current medication 3, 1

Non-Pharmacological Interventions

• Dietary modifications: small, frequent, bland meals; high-protein, low-fat meals; avoidance of specific food triggers 1
• These should be implemented alongside pharmacologic therapy, not as a substitute 1

Critical Pitfall to Avoid

Do not delay thiamine supplementation—Wernicke's encephalopathy can develop rapidly and cause permanent neurological damage 1, 2. Thiamine must be given before or concurrent with IV dextrose-containing fluids to prevent precipitating this complication 2.

When to Escalate Care

• If patient cannot maintain oral intake despite optimal antiemetic therapy, enteral or parenteral nutrition support may be necessary 1, 4
• Severe cases require involvement of obstetricians, gastroenterologists, nutritionists, and mental health professionals 2