What is the recommended treatment for a 6-week pregnant woman with hyperemesis gravidarum (severe morning sickness) requiring inpatient treatment?

Inpatient Treatment for Hyperemesis Gravidarum at 6 Weeks Gestation

For a 6-week pregnant woman requiring inpatient treatment for hyperemesis gravidarum, immediately initiate IV fluid resuscitation with electrolyte replacement (particularly potassium and magnesium), thiamine 200-300 mg IV daily to prevent Wernicke's encephalopathy, and antiemetic therapy starting with doxylamine-pyridoxine, escalating to metoclopramide or ondansetron if needed, with corticosteroids reserved only for severe refractory cases. 1

Immediate Stabilization (First 24 Hours)

Fluid and Electrolyte Management

• Aggressive IV fluid resuscitation is the cornerstone of initial management, targeting urine output of at least 1 L/day as an objective marker of adequate hydration 1
• Check and immediately correct electrolyte abnormalities, particularly potassium and magnesium, as these are commonly depleted and must be corrected to prevent cardiac arrhythmias 1
• Monitor for metabolic alkalosis from persistent vomiting using venous blood gas 1
• Perform electrocardiography to assess QT interval, as hypokalemia with or without hypomagnesemia prolongs QT and increases risk of ventricular arrhythmias 1
• Check liver function tests, as approximately 50% of patients will have abnormal AST and ALT (though rarely >1,000 U/L), which typically improve with rehydration 1

Critical Thiamine Supplementation

• Administer thiamine 200-300 mg IV daily immediately upon admission - this is non-negotiable at 6 weeks gestation with severe vomiting 1
• Pregnancy increases thiamine requirements, and hyperemesis rapidly depletes stores within 7-8 weeks of persistent vomiting, with reserves potentially exhausted after only 20 days of inadequate oral intake 1
• Continue IV thiamine for at least 3-5 days, then switch to oral maintenance (50-100 mg daily) once vomiting is controlled 1
• If any neurologic signs develop (confusion, ataxia, eye movement abnormalities), immediately escalate to thiamine 500 mg IV three times daily for suspected Wernicke's encephalopathy 1

Stepwise Antiemetic Protocol

First-Line Therapy (Start Immediately)

• Doxylamine 10-20 mg combined with pyridoxine (vitamin B6) 10-20 mg every 8 hours is the preferred initial antiemetic and is safe throughout pregnancy and breastfeeding 1
• This combination is recommended by the American College of Obstetricians and Gynecologists as first-line for both mild nausea/vomiting and hyperemesis gravidarum 1
• Alternative first-line agents include other antihistamines (promethazine, cyclizine) or phenothiazines (prochlorperazine, chlorpromazine), all sharing similar safety profiles 1

Second-Line Therapy (If First-Line Fails Within 24-48 Hours)

• Metoclopramide 5-10 mg IV every 6-8 hours is the preferred second-line agent when antihistamines fail, with less drowsiness, dizziness, and dystonia compared to promethazine 1
• No increased risk of major congenital defects found in meta-analysis of 33,000 first-trimester exposures 1
• Ondansetron should be used with extreme caution at 6 weeks gestation due to concerns about congenital heart defects when used before 10 weeks, though recent data suggest the risk is low 1
• The American College of Obstetricians and Gynecologists recommends using ondansetron on a case-by-case basis before 10 weeks of pregnancy 1
• Monitor QT interval with ondansetron, especially in patients with electrolyte abnormalities 1

Third-Line Therapy (Only for Severe Refractory Cases)

• Methylprednisolone 16 mg IV every 8 hours for up to 3 days should be reserved as last resort when both ondansetron and metoclopramide have failed 1
• After 3 days, taper over 2 weeks to lowest effective dose, with maximum duration of 6 weeks 1
• Use with extreme caution at 6 weeks gestation due to slight increased risk of cleft palate when given before 10 weeks, though data remain conflicting 1

Critical Monitoring Parameters

Daily Assessment Until Stable

• Body weight and weight trajectory - weight stabilization or gain (not continued loss) is a critical marker of clinical improvement 1
• Urine output (target ≥1 L/day) and resolution of ketonuria as objective markers of adequate rehydration 1
• Electrolytes and renal function, particularly potassium and magnesium levels 1
• Vomiting frequency - document number of episodes per day 1
• Ability to tolerate oral intake and maintain hydration 1

Severity Assessment

• Use the Motherisk Pregnancy-Unique Quantification of Emesis (PUQE) score serially to track symptom severity over time 1, 2
• Note that ketonuria alone is not associated with either diagnosis or severity of hyperemesis gravidarum 2

Common Pitfalls to Avoid

Medication Management Errors

• Never use PRN or intermittent dosing for severe cases - switch to around-the-clock scheduled antiemetic administration for continuous symptom control 1
• Withdraw phenothiazines or metoclopramide immediately if extrapyramidal symptoms develop 1
• Avoid drugs that prolong QT interval or exacerbate hypomagnesemia (proton-pump inhibitors, macrolides, fluoroquinolones) in patients with electrolyte abnormalities 1

Fluid Management Errors

• Do not tell patients to "drink more water" - hypotonic fluids can worsen fluid losses; use glucose-electrolyte oral rehydration solutions when oral intake resumes 1
• Avoid fluid overload - target near-zero fluid balance once initial dehydration is corrected 1

Thiamine Deficiency Prevention

• Never delay thiamine supplementation - start immediately upon admission, as reserves can be exhausted within 20 days of inadequate intake 1
• Do not rely on oral thiamine if patient is actively vomiting - use IV or IM route as oral absorption is unreliable 1

Discharge Criteria and Follow-Up

Requirements for Safe Discharge

• Sustained oral intake with ability to tolerate oral medications 1
• Weight stabilization or gain 1
• Resolution of ketonuria and normalization of electrolytes 1
• Reduced vomiting frequency and improved functional capacity 1

Patient Education

• Educate about high recurrence risk (40-92%) in subsequent pregnancies 1
• Inform that hyperemesis typically resolves by week 16-20 in 80% of cases, though 10% may experience symptoms throughout pregnancy 1
• Provide clear instructions for dietary modifications: small, frequent, bland meals (BRAT diet: bananas, rice, applesauce, toast), high-protein/low-fat meals, avoidance of strong odors and specific triggers 1

When to Escalate Care

Indications for Advanced Interventions

• If symptoms worsen despite maximal medical therapy with escalating vomiting (≥5-7 episodes daily), progressive weight loss ≥5% of pre-pregnancy weight, or inability to maintain oral intake of 1000 kcal/day for several days, consider nasojejunal feeding (preferred over nasogastric due to better tolerance) before escalating to total parenteral nutrition 1
• Multidisciplinary involvement (maternal-fetal medicine, gastroenterology, nutrition services, mental health professionals) is recommended for severe refractory cases, preferably at tertiary care centers 1
• Mental health support is important as anxiety and depression are common with severe hyperemesis 1