Hyperemesis gravidarum (HG) is a severe form of nausea and vomiting of pregnancy (NVP) affecting 0.3–3.6% of pregnancies, defined by intractable nausea/vomiting with onset before 16 weeks gestation, inability to eat or drink normally, weight loss >5% of pre-pregnancy weight, dehydration, and electrolyte imbalance. [1-2] It is a diagnosis of exclusion and the leading cause of hospital admission in the first trimester. [1] Emerging evidence implicates GDF15 (Growth Differentiation Factor 15), a fetal-derived hormone acting on the brainstem, as a key pathogenic factor. [2-3]
1. History
- Onset, duration, and frequency of nausea and vomiting — typically begins 4–6 weeks, peaks 8–12 weeks, resolves by 20 weeks in ~80%; persists throughout pregnancy in ~10% [3]
- Quantify oral intake: ability to tolerate solids, liquids, and medications
- Weight loss: compare to pre-pregnancy weight; >5% loss is diagnostic criterion [1-2]
- Triggers: specific foods, odors, activities [3]
- Prior pregnancies: history of HG in prior pregnancy significantly increases recurrence risk [3-4]
- Assess functional impairment: ability to work, perform daily activities [1]
- Screen for psychiatric symptoms: depression, anxiety, suicidal ideation (HG carries significant psychological burden) [3]
2. Alarm Features
- Wernicke's encephalopathy triad: ataxia, nystagmus, confusion — from thiamine deficiency [2][4]
- Hematemesis (Mallory-Weiss tear) or chest pain (Boerhaave syndrome) [4]
- Signs of severe dehydration: oliguria, tachycardia, orthostatic hypotension
- Neurologic symptoms: peripheral neuropathy, visual changes (vitamin deficiency) [4]
- Onset after the first trimester — raises concern for alternative diagnoses (appendicitis, pancreatitis, cholecystitis, bowel obstruction) [4-5]
- Fever, abdominal pain, or diarrhea — atypical for HG and should prompt workup for other etiologies [5]
- Inability to tolerate any oral medications or fluids despite outpatient antiemetics [1]
3. Medications
Stepwise antiemetic approach per ACOG and AGA guidelines: [3][6]
- First-line: Pyridoxine (vitamin B6) 10–25 mg q8h ± doxylamine 10–20 mg (FDA-approved combination) [3][6]
- Second-line: Ondansetron 4 mg IV/PO q8h (co-prescribe a laxative; use with caution <10 weeks due to possible cardiac defect risk); metoclopramide 10 mg IV/PO q8h (fewer side effects than promethazine); promethazine 12.5–25 mg IV/PO/PR q4–6h [1-3]
- Third-line: Methylprednisolone 16 mg IV q8h × 3 days, then taper over 2 weeks (avoid before 10 weeks if possible — possible cleft palate risk; max 6 weeks total) [1][3]
- Adjuncts: Ginger 250 mg PO QID (limited efficacy in severe HG); mirtazapine, olanzapine, gabapentin in refractory cases [6-7]
- Critical: Thiamine 100 mg IV/PO daily × 7 days minimum, then 50 mg daily until oral intake established — must be given BEFORE dextrose-containing fluids to prevent Wernicke's encephalopathy [1][3-4]
Contraindications/Cautions
- Avoid dextrose-containing IV fluids before thiamine replacement [1]
- Monitor for extrapyramidal symptoms with phenothiazines and metoclopramide — discontinue if reported [3]
- Ondansetron: obtain baseline ECG if QT prolongation risk; constipation is common [1]
4. Diet
- Acute: Small, frequent, bland meals; high-protein, low-fat foods; BRAT diet (bananas, rice, applesauce, toast) [3]
- Avoid strong odors, spicy, fatty, and acidic foods [3]
- Encourage oral hydration with small sips when tolerated; cold or carbonated beverages may be better tolerated
- Severe/refractory: Enteral nutrition (nasogastric preferred, then nasojejunal) before parenteral nutrition [4][6]
- Parenteral nutrition is last resort due to significant complications (line infections, thrombosis); PICC lines should not be used routinely [4][6]
- Refeeding syndrome prevention: Thiamine 100 mg daily before initiating dextrose, EN, or PN [4]
5. Review of Systems
- GI: Abdominal pain (suggests alternative diagnosis), hematemesis, dysphagia, diarrhea, constipation
- Neuro: Confusion, ataxia, nystagmus, paresthesias, visual changes (vitamin deficiency)
- GU: Decreased urine output, dysuria, frequency (UTI can coexist and worsen symptoms)
- Endocrine: Heat intolerance, tremor, palpitations (gestational transient thyrotoxicosis in ~60%) [2]
- Psych: Depression, anxiety, suicidal ideation — HG has a significant psychological toll [1][3]
- MSK: Muscle cramps, weakness (electrolyte derangement)
6. Collateral History and Family History
- Prior pregnancy history: HG recurrence rate is high [3-4]
- Family history of HG (genetic susceptibility via GDF15 variants) [2][8]
- Social context: financial impact of inability to work, childcare responsibilities, support system [1]
- Screen for eating disorders (can mimic or coexist) [5]
- Partner/family perception of symptom severity — HG is frequently dismissed by others [1]
7. Risk Factors
- Prior HG (strongest predictor) [3-4]
- Young age, primiparity, non-Caucasian ethnicity [5]
- Multiple gestation or molar pregnancy [3][5]
- Female fetus (singleton) [3]
- Pre-existing conditions: hyperthyroid disorders, diabetes mellitus, asthma, psychiatric illness [3]
- Non-smoker status [5]
- Family history of HG [8]
- Elevated GDF15 levels [2][8]
8. Differential Diagnosis
Must exclude other causes, especially with onset beyond the first trimester: [4-5]
- GI: Gastritis, GERD, cholecystitis/cholelithiasis, pancreatitis, appendicitis, hepatitis, bowel obstruction, peptic ulcer disease
- GU: UTI/pyelonephritis
- Endocrine/metabolic: Thyrotoxicosis, Addison's disease, hypercalcemia, diabetic ketoacidosis
- Pregnancy-related: Molar pregnancy, multiple gestation; in later pregnancy — preeclampsia/HELLP, acute fatty liver of pregnancy
- Neurologic: Migraine, increased intracranial pressure
- Psychiatric: Eating disorders (anorexia/bulimia)
- Distinguishing features: HG should NOT present with fever, significant abdominal pain, or diarrhea — these suggest alternative diagnoses [5]
9. Past Medical History
- Prior episodes of HG or severe NVP
- History of motion sickness or migraine (associated with NVP susceptibility)
- Thyroid disease
- Psychiatric history (depression, anxiety, eating disorders)
- Diabetes, epilepsy, HIV, adrenal insufficiency — inability to tolerate oral medications for these conditions is an indication for admission [1]
- Surgical history (prior abdominal surgery raising concern for adhesive obstruction)
10. Physical Exam
- Vitals: Tachycardia, orthostatic hypotension, weight (compare to pre-pregnancy baseline)
- General: Cachexia, muscle wasting, ptyalism (excessive salivation)
- HEENT: Dry mucous membranes, poor skin turgor, sunken eyes; check for goiter
- Abdominal: Should be soft, non-tender — tenderness or peritoneal signs suggest alternative diagnosis; assess for epigastric tenderness
- Neuro: Assess for nystagmus, ataxia, confusion (Wernicke's); peripheral neuropathy (B12/B6 deficiency) [3-4]
- Fundal height: Assess for size-dates discrepancy (molar pregnancy, multiple gestation)
11. Lab Studies
- Baseline: CBC, BMP (Na, K, Mg, Cl, BUN, Cr, glucose), urinalysis with ketones [4][9]
- Hepatic: AST/ALT (elevated in 40–50% of HG; typically <300 U/L), total bilirubin (<4 mg/dL) [4][6]
- Thyroid: TSH, free T4 — transient biochemical hyperthyroidism in ~60% (suppressed TSH, elevated free T4); do not treat with antithyroid drugs — manage supportively [2][6]
- Additional: Amylase/lipase (if pancreatitis suspected; mild elevation up to 5× normal can occur in HG); quantitative β-hCG (if molar pregnancy suspected) [6]
- Nutritional: Thiamine level if Wernicke's suspected; INR/PT if prolonged vomiting (vitamin K deficiency) [4]
- Key abnormalities: Hyponatremia, hypokalemia, hypomagnesemia, hypochloremic metabolic alkalosis, ketonuria, elevated hematocrit (hemoconcentration), AKI [2][4]
- Note: Ketonuria can guide need for fluid replacement but should not be used alone to diagnose HG [4][10]
12. Imaging
- First-line: Pelvic/obstetric ultrasound — assess for molar pregnancy, multiple gestation, fetal viability and growth [3][6]
- If atypical features: Abdominal ultrasound to rule out gallstones, portal vein thrombosis, hepatobiliary or renal pathology [3]
- When imaging is unnecessary: Typical first-trimester presentation with known viable intrauterine pregnancy and no alarm features
- Upper endoscopy is rarely indicated but may be considered if hematemesis or concern for esophageal injury [11]
13. Special Tests
- PUQE-24 Score (Pregnancy-Unique Quantification of Emesis): Validated tool to quantify severity over 24 hours; useful for tracking treatment response [1][10]
- HELP Score (Hyperemesis-Level Prediction): 12-question validated tool, may be more accurate at the severe end of the spectrum [1]
- Point-of-care: Urine ketones (bedside dipstick), point-of-care electrolytes, bedside glucose
- Urine specific gravity: Elevated in dehydration
14. ECG
- Obtain if significant electrolyte derangement (hypokalemia, hypomagnesemia) — risk of QT prolongation and arrhythmias [4]
- Obtain before ondansetron in patients with risk factors for QT prolongation
- Watch for: U waves (hypokalemia), prolonged QT, ST changes
15. Assessment
Hyperemesis gravidarum is a clinical diagnosis of exclusion characterized by severe, intractable NVP with onset before 16 weeks, weight loss >5%, dehydration, and electrolyte disturbance. [1] Severity ranges from mild (manageable outpatient) to life-threatening (Wernicke's encephalopathy, Boerhaave syndrome, renal failure). [4]
Complications to consider:
- Maternal: Wernicke's encephalopathy, Mallory-Weiss tear, esophageal rupture, AKI, coagulopathy (vitamin K deficiency), peripheral neuropathy, pneumothorax, splenic avulsion, psychological morbidity [4]
- Fetal: Low birth weight, small for gestational age, preterm delivery [3]
- Symptoms typically improve by 20 weeks but persist throughout pregnancy in ~10% of cases [3]
16. Treatment Plan
Initial stabilization (ED/inpatient)
- IV fluids: 0.9% normal saline, typically 3 L/day with 40 mmol KCl per liter bag; daily electrolyte monitoring [1]
- Thiamine 100 mg IV before any dextrose-containing fluids [1][3][6]
- Avoid dextrose-containing fluids until thiamine repleted [1]
- Parenteral antiemetics if unable to tolerate oral medications
Stepwise antiemetic therapy: [2-3][6]
- Pyridoxine 10–25 mg q8h ± doxylamine 10–20 mg
- Add ondansetron 4 mg IV q8h or metoclopramide 10 mg IV q8h
- Methylprednisolone 16 mg IV q8h × 3 days → taper (last resort)
- Refractory: consider mirtazapine, olanzapine, gabapentin [7]
Nutritional support (if oral intake fails): [4][6]
- Enteral nutrition (nasogastric → nasojejunal) is preferred first-line
- Parenteral nutrition only as last resort
- Thiamine supplementation throughout
Acid suppression: H2 blockers or PPIs if concurrent GERD/esophagitis [3]
17. Disposition
Admission criteria: [1]
- Continuous NVP with inability to keep down oral antiemetics despite alternative routes (rectal, sublingual)
- Clinical dehydration with weight loss >5% despite outpatient antiemetics
- Electrolyte derangement requiring IV correction (significant hyponatremia, hypokalemia)
- AKI or organ dysfunction
- Suspected comorbidity (UTI, inability to tolerate essential oral medications for epilepsy, diabetes, HIV, etc.)
- Neurologic signs concerning for Wernicke's encephalopathy
Discharge criteria: [1]
- Able to tolerate oral antiemetics, nutrition, and hydration
- Electrolytes corrected
- Weight stable or improving
- Adequate outpatient follow-up arranged
Observation/ambulatory care: Outpatient IV hydration units or virtual wards can prevent admission and improve satisfaction when available [1]
Specialist consultation triggers: OB/GYN (all cases); GI if atypical features or refractory; nutrition/dietitian for prolonged poor intake; psychiatry/psychology for significant psychological distress [3]
18. Follow Up / Return Precautions
- Follow-up: OB within 48–72 hours of ED discharge; sooner if symptoms not improving
- Return immediately for: Inability to keep down any fluids or medications for >12–24 hours, bloody vomit, confusion/ataxia/visual changes, decreased urine output, severe abdominal pain, fever
- Counseling: HG is a real medical condition — validate symptoms; discuss expected course (most improve by 20 weeks); address mental health proactively [1]
- Medication adherence: Antiemetics should be continued until symptoms would have naturally resolved — premature discontinuation leads to distressing recurrence [1]
- Expected recovery: Symptoms resolve by 20 weeks in ~80%; ~10% have symptoms throughout pregnancy; rarely extends into postpartum [3-4]
- Future pregnancies: High recurrence risk — pre-emptive doxylamine/pyridoxine starting at conception may improve outcomes in subsequent pregnancies [2]
References
1. Hyperemesis Gravidarum. — Nana M, Painter R, Williamson C, Nelson-Piercy C. Lancet. 2026.
2. Pregnancy and the Liver. — Rahim MN, Williamson C, Kametas NA, Heneghan MA. Lancet. 2025.
3. AGA Clinical Practice Update on Pregnancy-Related Gastrointestinal and Liver Disease: Expert Review. — Kothari S, Afshar Y, Friedman LS, Ahn J. Gastroenterology. 2024.
4. Hyperemesis Gravidarum and Nutritional Support. — Elkins JR, Oxentenko AS, Nguyen LAB. The American Journal of Gastroenterology. 2022.
5. Interventions for Treating Hyperemesis Gravidarum. — Boelig RC, Barton SJ, Saccone G, et al. The Cochrane Database of Systematic Reviews. 2016.
6. ACOG Practice Bulletin No. 189: Nausea and Vomiting of Pregnancy. — Committee on Obstetric Practice—This Practice Bulletin was developed by the American College of Obstetricians and Gynecologists’ Committee on Practice Bulletins—Obstetrics in collaboration with Susan M Obstetrics and Gynecology. 2018.
7. Inpatient Management of Hyperemesis Gravidarum. — Clark SM, Zhang X, Goncharov DA. Obstetrics and Gynecology. 2024.
8. Hyperemesis Gravidarum Revisited: From GDF15 Biology to Precision Multimodal Therapy. — Alshaikh ABA, Al-Kuraishy HM, Kafy S, et al. Naunyn-Schmiedeberg's Archives of Pharmacology. 2026.
9. Heartburn, Nausea, and Vomiting During Pregnancy. — Dunbar K, Yadlapati R, Konda V. The American Journal of Gastroenterology. 2022.
10. Review Article: Management of Hyperemesis Gravidarum and Nausea and Vomiting in Pregnancy. — Lowe SA, Steinweg KE. Emergency Medicine Australasia : EMA. 2022.
11. Reproductive Health and Liver Disease: Practice Guidance by the American Association for the Study of Liver Diseases. — Sarkar M, Brady CW, Fleckenstein J, et al. Hepatology. 2021.