What is the management of hyperemesis gravidarum?

Management of Hyperemesis Gravidarum

Begin immediate IV fluid resuscitation and thiamine supplementation, followed by stepwise antiemetic therapy starting with doxylamine-pyridoxine combination, escalating to metoclopramide, then ondansetron, and reserving corticosteroids as last resort for refractory cases. 1

Initial Stabilization

Fluid and Electrolyte Management:

• Administer IV fluid resuscitation immediately to correct dehydration, which typically improves associated liver enzyme abnormalities 1, 2
• Replace electrolytes with particular attention to potassium and magnesium levels 1, 2
• Check electrolyte panel, liver function tests (approximately 50% will have elevated AST/ALT, rarely >1,000 U/L), and urinalysis for ketonuria 1, 2

Critical Thiamine Supplementation:

• Start thiamine 100 mg daily orally for minimum 7 days, then 50 mg daily maintenance until adequate oral intake is established 1
• If vomiting persists or patient cannot tolerate oral intake, switch immediately to IV thiamine 200-300 mg daily to prevent Wernicke encephalopathy 1, 2
• Pregnancy depletes thiamine stores within 7-8 weeks of persistent vomiting, with complete exhaustion possible after only 20 days of inadequate intake 2

Severity Assessment

• Use the Pregnancy-Unique Quantification of Emesis (PUQE) score to assess severity, evaluating duration of nausea, frequency of vomiting, and frequency of retching over 12 hours 3, 1
• Document weight loss (≥5% of pre-pregnancy weight defines hyperemesis gravidarum) and signs of dehydration 3, 2
• Perform abdominal ultrasonography to detect multiple or molar pregnancies and rule out hepatobiliary causes 1, 2
• Screen for thyroid dysfunction as hyperemesis can be associated with biochemical hyperthyroidism (undetectable TSH, elevated FTI) 3

Stepwise Pharmacologic Management

First-Line Antiemetic:

• Doxylamine-pyridoxine combination is the preferred initial antiemetic, safe throughout pregnancy and breastfeeding 1, 2
• Alternative first-line agents include other antihistamines (promethazine, cyclizine) and phenothiazines (prochlorperazine, chlorpromazine) with similar safety profiles 2

Second-Line Antiemetic:

• Metoclopramide is the preferred second-line agent when first-line antihistamines fail, with similar efficacy to promethazine but fewer side effects including less drowsiness, dizziness, dystonia, and fewer discontinuations 1, 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 1, 2
• The American College of Obstetricians and Gynecologists recommends using ondansetron on a case-by-case basis before 10 weeks of pregnancy 1
• Monitor for QT interval prolongation with ondansetron, especially in patients with electrolyte abnormalities 2

Third-Line Therapy:

• Methylprednisolone should be reserved as last resort for severe hyperemesis that fails other therapies: 16 mg IV every 8 hours for up to 3 days, then taper over 2 weeks to lowest effective dose, maximum duration 6 weeks 1, 2
• Use with caution in first trimester due to slight increased risk of cleft palate when given before 10 weeks gestation 1, 2

Alternative Pharmacotherapeutics for Refractory Cases:

• Consider olanzapine and gabapentin when typical antiemetics fail 2, 4
• Meta-analysis shows no significant efficacy difference among commonly used antiemetics (metoclopramide, ondansetron, promethazine), so medication selection should be based on safety profile and gestational age 1

Important Caveats

• Withdraw phenothiazines or metoclopramide immediately if extrapyramidal symptoms develop 2
• If liver chemistry abnormalities persist despite symptom resolution, investigate for another etiology 2
• Severe cases with persistent weight loss may require hospitalization for IV hydration, enteral or parenteral nutrition 2, 4

Monitoring and Follow-Up

• Regularly assess hydration status, electrolyte balance, and symptom control using PUQE score 3, 1, 2
• Monitor fetal growth, especially if maternal weight gain is insufficient, with monthly fetal growth scans from viability in severe cases 3, 1, 2
• Symptoms resolve by week 16 in >50% of patients and by week 20 in 80%, though 10% experience symptoms throughout pregnancy 1, 2

Multidisciplinary Management

• Severe cases require involvement of obstetricians, gastroenterologists, nutritionists, and mental health professionals 1, 2

Patient Education

• Educate patients about the high recurrence risk (40-92%) in subsequent pregnancies 1, 2
• Untreated hyperemesis is associated with low birth weight, small for gestational age infants, premature delivery, and decreased maternal quality of life 2