Women's Health

Hyperemesis gravidarum

Hyperemesis gravidarum is severe nausea and vomiting of early pregnancy that prevents normal eating and drinking and limits daily function; assess clinically for dehydration, weight loss, electrolyte disturbance and alternative diagnoses, then escalate antiemetics and fluids through community, ambulatory or inpatient care.

In a nutshell

Hyperemesis gravidarum is severe early-pregnancy nausea and vomiting that prevents normal eating and drinking and limits daily function. Assess hydration, weight, nutrition, oral-medication tolerance, PUQE/HELP score, electrolytes and alternative diagnoses. Urine ketones are not a reliable marker of dehydration or severity. Escalate from community antiemetics to ambulatory or inpatient fluids, give thiamine before dextrose or parenteral nutrition, and prevent VTE in hospital.

Classic presentation

Early-pregnancy vomiting with inability to retain food, fluids or medicines, dehydration, weight loss and substantial functional impairment; complications may include electrolyte or renal disturbance and thiamine deficiency.

Key points

HG is diagnosed clinically when early-pregnancy nausea or vomiting prevents normal eating and drinking and strongly limits activities; dehydration contributes but is not defined by a urine dipstick.
Use PUQE or HELP plus history, examination, weight, oral intake and laboratory results to assess severity and response.
Ketonuria is not an indicator of dehydration or HG severity and should not be used alone to decide admission or monitor response.
Community care uses antiemetics and oral support; ambulatory day care is appropriate when community measures fail but the patient is clinically suitable; inpatient care is needed when oral treatment fails, dehydration or significant weight loss persists, or comorbidity is present.
Use normal saline with potassium replacement as indicated and daily electrolyte monitoring; give thiamine before dextrose or parenteral nutrition in patients with vomiting or severely reduced intake.
Use first-line antihistamine, phenothiazine or doxylamine/pyridoxine treatment, then different classes or combinations; ondansetron is a supported second-line option and metoclopramide needs extrapyramidal-risk awareness.
Offer LMWH thromboprophylaxis to admitted patients unless contraindicated and assess VTE risk in community care.
Consider steroids only for refractory disease after standard treatment and with specialist oversight; address mental health and the wider impact of HG throughout care.

First-line investigation

Structured clinical assessment with PUQE or HELP, hydration and weight assessment, appropriate blood tests and urine culture, with pregnancy ultrasound to assess gestation, viability, multiple pregnancy or trophoblastic disease.

Management

Recognise complications and escalate safely

Urgently assess instability, AKI, electrolyte or acid-base disturbance, Wernicke features, hypoglycaemia, severe distress and alternative acute diagnoses; arrange obstetric/medical admission when present.^1,2

Assess severity without overvaluing ketones

Use history, examination, hydration, weight, oral intake, daily function, PUQE or HELP scoring and appropriate blood tests; urine ketones do not grade dehydration or HG severity.^1,2
Consider UTI and other alternative diagnoses, and arrange ultrasound to confirm pregnancy and assess for multiple or trophoblastic pregnancy without delaying treatment.^1,3

Prevent nutritional, renal and thrombotic complications

Use saline and electrolyte replacement with monitoring, give thiamine before dextrose or parenteral nutrition when intake has been poor, assess VTE risk and offer LMWH to admitted patients unless contraindicated.^1,4

Step antiemetics and choose the right care setting

Start pregnancy-safe antiemetics, use different classes or combinations when response is inadequate, offer ambulatory IV therapy after community-treatment failure and admit when oral treatment fails, dehydration or significant weight loss persists, or comorbidity is present.^1,2,4
Reserve corticosteroids for refractory symptoms after standard treatment and use them with specialist oversight, monitoring for maternal adverse effects.^1,2

Plan review, readmission prevention and psychological support

Give a written antiemetic and hydration plan, clear return precautions and prompt review after discharge; address nutrition, mental health, domestic and social support, recurrent HG planning and ongoing antenatal care.^1,3

Exam traps

Do not use ketonuria as a proxy for dehydration or severity; the 2024 RCOG guideline explicitly advises against it.
Give thiamine before dextrose or parenteral nutrition when vomiting or reduced intake is prolonged; Wernicke encephalopathy is preventable but serious.
Do not treat all vomiting as HG without considering UTI, gastroenteritis, abdominal pathology, endocrine or metabolic disease and pregnancy complications.
Do not use a fixed PUQE cut-off as the sole reason to admit; combine scores with dehydration, weight loss, oral-medication failure, comorbidity and social safety.
Do not leave VTE prevention out of inpatient management: dehydration and immobility increase risk.

Illustrations

Pregnancy hormones and nausea severityDiagram showing early-pregnancy hormonal and placental factors associated with nausea and vomiting, while avoiding a single-cause or fixed-threshold explanation.PassFinals · original

Vomiting complications and treatment prioritiesDiagram tracing persistent vomiting through reduced intake, dehydration, electrolyte and renal complications, thiamine deficiency and thrombotic risk, with assessment and treatment points.PassFinals · original

Clinical severity assessmentIllustration of structured history, examination, PUQE or HELP scoring and treatment response; urine ketones are not presented as a stand-alone severity score.PassFinals · original

Key sources

This page is exam revision material, not medical advice, and must not be used for patient care. Always check drug doses against the BNF and current guidance. Full disclaimer.