Hyperemesis Gravidarum — Assessment, Treatment & Warning Signs
Hyperemesis gravidarum is severe, persistent vomiting in early pregnancy that causes dehydration, weight loss and electrolyte
disturbance. The pathway is to grade it, exclude other causes, replace fluids and thiamine, and escalate antiemetics in steps —
while watching for the dangerous complication, Wernicke's encephalopathy.
🎯 AT A GLANCE — NVP VERSUS HYPEREMESIS
Nausea and vomiting of pregnancy (NVP) affects 70–80% of pregnancies; it starts around 4–6 weeks, peaks at about 9 weeks, and settles by 16–20 weeks in most
Hyperemesis gravidarum (HG) is the severe end — about 0.3–3% of pregnancies: persistent vomiting with weight loss over 5% of pre-pregnancy weight, dehydration (ketonuria) and electrolyte disturbance
About 1 in 10 women with HG continue to vomit until delivery
HG is not “just morning sickness”. It is a serious, treatable condition that can cause Wernicke's encephalopathy, loss of work and mental-health harm — treat early and take the woman seriously.
🧬 WHY IT HAPPENS — AND WHO IS AT RISK
Mechanisms
hCG peaks at 9–12 weeks, matching the timing of symptoms
GDF15 — a hormone made by the placenta that acts on the brainstem; maternal sensitivity to it decides severity
Oestrogen, progesterone and slowed gastric emptying add to the load
Transient thyroid stimulation in many (see work-up)
Risk Factors
Previous HG or a mother or sister with HG
Multiple pregnancy and molar pregnancy (high hCG)
Nulliparity, young age, obesity or a history of migraine and motion sickness
🔎 BEFORE LABELLING IT HG — EXCLUDE OTHER CAUSES
Typical HG: starts before 9 weeks, comes without fever, severe pain or headache, and with a normal abdomen
Think again if: vomiting begins after 9–10 weeks, or there is abdominal pain, fever, diarrhoea, headache, neck stiffness, or urinary symptoms
Gastrointestinal: gastroenteritis, hepatitis, pancreatitis, cholecystitis, appendicitis, peptic ulcer
Urinary and metabolic: UTI or pyelonephritis, diabetic ketoacidosis, hyperthyroidism, Addison's disease
Pregnancy-related: multiple pregnancy and molar pregnancy — an early ultrasound is part of the work-up (see our GTD guide)
📏 ASSESS SEVERITY — THE PUQE SCORE
| In the last 12 hours | 1 | 2 | 3 | 4 | 5 |
|---|
| Hours of nausea | None | ≤ 1 | 2–3 | 4–6 | > 6 |
| Episodes of vomiting | None | 1–2 | 3–4 | 5–6 | ≥ 7 |
| Episodes of retching | None | 1–2 | 3–4 | 5–6 | ≥ 7 |
Mild: total score ≤ 6
Moderate: total score 7–12
Severe: total score ≥ 13 — consider admission
Also record: weight against pre-pregnancy weight, hydration, pulse, blood pressure, and ketones on urine dipstick. Repeat at every visit.
🔬 INVESTIGATIONS
1
Urine ketones and urinalysis with culture2
Urea, creatinine and electrolytes — look for low potassium, low sodium and a metabolic alkalosis; add magnesium, calcium and phosphate if admitted3
Full blood count, glucose, and liver function (mildly raised transaminases are common)4
TSH and free T4 — frequently shows transient hyperthyroidism; treat only if clinical thyrotoxicosis is present5
Ultrasound to confirm viability and exclude molar or multiple pregnancy6
Amylase or lipase, and blood gas if there is pain or severe illness📈 STEPWISE MEDICAL TREATMENT
Step 1 — LifestyleSmall, frequent, bland or cold meals; avoid triggers such as strong smells; ginger and P6 acupressure may help; take iron-containing vitamins at night or pause them
Step 2 — First-line drugsPyridoxine (vitamin B6) 10–25 mg three to four times daily, with or without doxylamine; or an antihistamine: promethazine 12.5–25 mg every 4–6 h, or cyclizine 50 mg three times daily
Step 3 — Second-line drugsMetoclopramide 5–10 mg three times daily, or prochlorperazine; ondansetron 4–8 mg every 8 h if still vomiting (small possible first-trimester risk; may cause constipation or QT prolongation)
Step 4 — RefractoryCorticosteroids (hydrocortisone 100 mg IV twice daily, then oral prednisolone tapered) only after 10 weeks; other options include mirtazapine or gabapentin, with specialist advice
Combine drugs from different classes when one fails, and use the oral, rectal, or parenteral route that the woman can keep down
Add a PPI or H2 blocker for reflux; treat constipation, which makes nausea worse
Doses are typical adult doses. Always check local formulary and the individual's QT risk, other drugs, and kidney function.
🏥 WHEN TO ADMIT — AND WHAT INPATIENT CARE INVOLVES
Admit if: PUQE ≥ 13, persistent vomiting with ketonuria despite oral antiemetics, weight loss over 5%, electrolyte disturbance, an inability to keep down fluids or medicines, or a coexisting condition such as diabetes
Day-care or ambulatory IV therapy works for many moderate cases and avoids full admission
IV fluidsIsotonic saline or Hartmann's with potassium added to correct deficits; monitor sodium and avoid rapid correction
ThiamineGive thiamine before any dextrose-containing fluid — 100 mg IV daily during admission, or oral thiamine 100 mg daily when vomiting settles
ElectrolytesReplace potassium, magnesium and phosphate; correct hyponatraemia slowly to avoid osmotic demyelination
ThromboprophylaxisLMWH for admitted women, with compression stockings and early mobilisation, because dehydration and immobility raise VTE risk
NutritionRefractory cases: nasogastric or nasojejunal feeding, or parenteral nutrition as a last resort; watch for refeeding syndrome
🚨 WERNICKE'S ENCEPHALOPATHY — A MEDICAL EMERGENCY
Suspect it in any woman with prolonged vomiting who develops confusion, drowsiness, unsteady gait, double vision, nystagmus, or ophthalmoplegia — the full triad is rare Treat at once with IV thiamine, 200–500 mg three times daily, before any glucose; do not wait for the scan or the blood test Replace magnesium, correct the electrolytes, and seek urgent neurology and critical-care advice Untreated, it leaves permanent memory loss (Korsakoff syndrome) or death — and the fetus is at risk ⚠️ COMPLICATIONS
Maternal
Wernicke's encephalopathy (thiamine deficiency)
Hypokalaemia, hyponatraemia, and metabolic alkalosis
Mallory–Weiss tear, and rarely oesophageal rupture
VTE, vitamin K deficiency with bleeding, and refeeding syndrome
Depression, anxiety and traumatic stress
Fetal / Neonatal
Weight loss over 5% is linked to low birth weight and preterm birth
Most babies are healthy when HG is treated well
Folate, iron, and vitamin deficiencies need prevention
Prolonged severe cases need growth scans
💛 COUNSELLING, SUPPORT & FUTURE PREGNANCIES
Recognise the burden: HG can cause isolation, job loss, and thoughts of termination; ask about mood and offer psychological support
Reassure: antiemetics at standard doses have wide safety data, and untreated HG carries more risk than most treatments
Most women improve by 16–20 weeks, though some need treatment to term
Recurrence is common (often more than half of later pregnancies) — offer pre-emptive antiemetics and early review in the next pregnancy, ideally starting before symptoms begin
Termination of pregnancy is considered only in severe, refractory cases after full counselling and specialist input
⛔ WHAT NOT TO DO
Do not dismiss her as having “morning sickness” — early treatment prevents admission
Do not give dextrose before thiamine in a vomiting woman
Do not correct sodium quickly, and do not give steroids before 10 weeks
Do not treat transient biochemical hyperthyroidism with antithyroid drugs unless there is true thyrotoxicosis
Do not withhold safe antiemetics from fear of birth defects — discuss the evidence
Five habits for every woman with severe vomiting in pregnancy.
H
Hydrate — isotonic IV fluids with potassium, and replace electrolytes
Y
Yield to a stepwise antiemetic plan — B6 and antihistamines first, then add and escalate
P
PUQE score, weight, and urine ketones — score her at every visit
E
Exclude other causes and examine for molar or multiple pregnancy
R
Replace thiamine before dextrose, and suspect Wernicke's in any confusion
Remember: early, adequate treatment shortens the illness, protects the brain, and spares the mother a long admission.
