FFinalistSouthampton · 2027
Obstetrics & gynaecology
AKT · Obstetrics & gynaecology/Early pregnancy

Hyperemesis gravidarum

Severe pregnancy nausea/vomiting (high βhCG)

Overview

Severe, persistent nausea and vomiting of pregnancy causing dehydration, weight loss (>5%) and electrolyte/ketone disturbance — beyond ordinary morning sickness. Associated with high βhCG (multiple/molar pregnancy).

Recognise

  • Protracted vomiting, unable to keep food/fluids down, weight loss >5%
  • Dehydration, ketosis, electrolyte disturbance (hypokalaemia, hyponatraemia)
  • Peaks ~8–12 weeks; PUQE score grades severity

Red flags

  • Severe dehydration, ketonuria, hyponatraemia/hypokalaemia → admit; consider Wernicke’s (give thiamine)

Differentials & how to tell them apart

Molar pregnancyvery high hCG, "snowstorm" USS, large-for-dates uterus
Multiple pregnancyhigh hCG, multiple sacs on USS
Gastroenteritis/UTI/DKAfever/diarrhoea, dysuria, glucose
ThyrotoxicosisTFTs

Investigations

Urine ketones/dip, U&E, FBC, weight; USS to exclude multiple/molar pregnancy; TFTs (mild gestational thyrotoxicosis common).

Management

First-line antiemetic (cyclizine or promethazine) + fluids/hydration

  1. 1First-line antiemetic: antihistamine (cyclizine, promethazine) or phenothiazine (prochlorperazine).Gate: If first-line fails → ondansetron or metoclopramide (limit metoclopramide to 5 days — extrapyramidal effects)
  2. 2Admit if unable to tolerate oral/dehydrated: IV rehydration, replace electrolytes, THIAMINE (prevent Wernicke’s), VTE prophylaxis, antiemetics.
Antiemetics (cyclizine, promethazine, prochlorperazine) — first-line
Ondansetron / metoclopramide — second-line
IV fluids + thiamine + VTE prophylaxis — if admitted

Key points

Always give thiamine and avoid glucose-only fluids first (Wernicke’s risk). Exclude molar/multiple pregnancy with USS.

Monitor & prognosis

Weight, ketones, electrolytes, hydration.

Usually settles by mid-pregnancy.

Source: RCOG; NICE CKS Nausea/vomiting in pregnancy