Hyperemesis gravidarum (HG) = severe, persistent nausea and vomiting in pregnancy → leads to weight loss, dehydration, and electrolyte imbalance. ⚠️ More severe than typical “morning sickness” and often requires hospital care. Incidence: ~1 in 100 pregnancies in the UK.

🧬 Pathophysiology

High β-hCG and oestrogen levels (peaks in first trimester).
More common in multiple pregnancy 👶👶, molar pregnancy, and personal/family history of HG.
Potential roles: genetic predisposition, thyroid dysfunction, gastrointestinal motility disorders.

📋 Clinical Features

Persistent nausea and vomiting 🤢 (cannot tolerate oral intake).
Weight loss >5% of pre-pregnancy weight ⚖️.
Signs of dehydration: dry mucous membranes, tachycardia, hypotension.
Electrolyte imbalance → hypokalaemia, hyponatraemia.
Ketonuria (starvation ketosis) on urine dipstick.
Dizziness, fatigue, reduced urine output.

🔍 Investigations

🧪 Urine dipstick: ketones, specific gravity.
🩸 Bloods: U&E (K⁺, Na⁺), LFTs, FBC, TFTs (exclude hyperthyroidism).
💉 Venous blood gas: check for metabolic alkalosis/acidosis.
🖥️ Ultrasound: exclude multiple pregnancy and trophoblastic disease.

📊 Hyperemesis Gravidarum – Summary Table

Category	Feature	Investigation	Management	OSCE Tip
🤢 Clinical	Persistent vomiting, >5% weight loss, dehydration, ketonuria	History, examination, urine dipstick	Supportive care, IV fluids, thiamine	Always assess hydration & weight loss ⚖️
🧪 Labs	Electrolyte disturbances, LFT changes, ketones	U&E, LFTs, FBC, VBG	Correct electrolyte imbalances, monitor biochemistry	Identify hypokalaemia → cardiac risk ⚡
💊 Medical	Refractory vomiting	Clinical assessment	Antiemetics: first-line antihistamines (cyclizine/promethazine), second-line metoclopramide/ondansetron, corticosteroids if severe	Start thiamine before dextrose 🧠
🏥 Hospital	Unable to tolerate oral intake, persistent ketonuria	Clinical + labs	IV fluids (NS + KCl), nutritional support (enteral feeding/TPN if needed)	Monitor maternal and fetal wellbeing 🩺
⚠️ Red Flags	Molar pregnancy, hyperthyroidism, severe electrolyte imbalance	Ultrasound, TFTs, beta-hCG	Specialist referral, treat underlying cause	Consider molar pregnancy if uterus large-for-dates

🚩 Complications

Maternal: dehydration, electrolyte imbalance, Wernicke’s encephalopathy, Mallory–Weiss tears, thromboembolism.
Fetal: intrauterine growth restriction (IUGR), low birth weight, preterm birth if prolonged/severe.

📌 Prognosis

Typically improves by 16–20 weeks, but may persist in some women.
Recurrence in subsequent pregnancies: 15–20%.
Supportive care and reassurance are key.

📖 Clinical Pearls

💡 Always give thiamine before IV dextrose to prevent Wernicke’s encephalopathy.
❌ Avoid ondansetron in first trimester unless refractory (small potential teratogenic risk).
⚠️ Suspect molar pregnancy if HG is severe, early onset, or uterus large-for-dates.
👩‍⚕️ Multidisciplinary care (dietitians, obstetricians, mental health) is important.

📚 References

RCOG Green-top Guideline No. 69: Nausea and Vomiting in Pregnancy
NICE CKS: Nausea and Vomiting in Pregnancy
BMJ Best Practice: Hyperemesis gravidarum

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Hyperemesis Gravidarum