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Hyperemesis Gravidarum

Hyperemesis gravidarum (HG) affects 0.3–2% of pregnancies: intractable vomiting with weight loss, dehydration and electrolyte disturbance. It is the commonest reason for hospital admission in the first trimester. Thiamine matters because Wernicke's…

RCOG Green-top 69 (2024)

The pathway

1 · Assess severity — not with ketones

Use PUQE or HELP
Admit for: unable to keep down fluids or antiemetics · weight loss · electrolyte disturbance · destabilising comorbidity

Do not use urinary ketones. GTG69 (2024) is explicit: ketonuria is not an indicator of dehydration or severity, and measuring it misleads judgement about hydration.

2 · IV fluids

0.9% NaCl with KCl 20–40 mmol/L
Avoid dextrose until thiamine given
Correct K⁺, Na⁺, Mg²⁺

3 · Thiamine — everyone admitted, before dextrose

All women admitted with prolonged vomiting, oral or IV
Before dextrose or parenteral nutrition — a carbohydrate load in a thiamine-deplete woman precipitates Wernicke's
Oral is adequate for most. Parenteral is for those who cannot take or absorb it
Suspected Wernicke's is a separate, higher treatment dose
If she is hypoglycaemic, treat it now — never delay glucose to find thiamine

4 · Antiemetics

Step up: cyclizine 50mg TDS → promethazine → metoclopramide → ondansetron → chlorpromazine.

5 · Monitor

Daily U&E, especially K⁺
LFTs
TFTs — transient hyperthyroidism in HG is biochemical. Do not treat with antithyroid drugs

6 · Discharge planning

Discharge when tolerating oral fluids and antiemetics and electrolytes corrected
Not ‘when ketones clear’ — that criterion has gone
Continue oral antiemetics rather than stopping at the door; relapse and readmission are common
Signpost to Pregnancy Sickness Support, and ask about mood

Drugs

Drug	Dose	Route	Notes
Thiamine (oral)	Per local policy	PO	Adequate for most admissions. Give before dextrose or parenteral nutrition.
Pabrinex (thiamine IV)	Per local policy	IV	When oral is not possible or not absorbed. Suspected Wernicke's is a separate, higher-dose treatment regimen — treat, do not prophylax, and involve neurology.
Cyclizine	50mg	TDS PO/IV/IM	First-line antiemetic. Safe in pregnancy.
Ondansetron	4–8mg	BD PO or IV	Off-label but widely used. Some evidence of small cleft palate risk <10 weeks — informed consent.
Metoclopramide	10mg	TDS PO/IV/IM	Avoid prolonged use (extrapyramidal). Max 5 days.
0.9% NaCl + KCl	1–2L over 6h	IV	Avoid dextrose-containing fluid until thiamine has been given. Exception: treat hypoglycaemia immediately — never delay glucose for a life-threatening low sugar.

When to escalate

Wernicke's features (confusion, nystagmus, ataxia) — high-dose IV Pabrinex, neurology,Mallory-Weiss tear — GI review, endoscopy if significant haematemesis,Severe hyponatraemia — slow correction (no faster than 10 mmol/L/24h to prevent pontine myelinolysis),Refractory HG — consider PEG/NJ tube or TPN, dietitian + gastroenterology

Reference: RCOG Green-top Guideline No. 69, 2nd edition (2024) — Nausea and vomiting in pregnancy and hyperemesis gravidarum

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