🔑 Key Learning

  • Severe form of pregnancy-related vomiting, typically in the first trimester.
  • Associated with weight loss, dehydration, and electrolyte disturbance.
  • Strongly linked to elevated hCG levels (e.g. multiple pregnancy, molar pregnancy).
  • 1st line antiemetics: promethazine, cyclizine, or prochlorperazine.
  • Always consider thiamine supplementation to prevent Wernicke’s encephalopathy.

🧬 Pathophysiology

  • Exact cause unknown.
  • Thought to be related to high levels of hCG and oestrogen.
  • More common in:
    • Multiple pregnancies
    • Molar pregnancies
    • Nulliparity
    • Previous history of hyperemesis

đź‘€ Clinical Features

  • Persistent, protracted nausea and vomiting (beyond typical morning sickness)
  • >5% pre-pregnancy weight loss
  • Dehydration: dry mucous membranes, reduced skin turgor, dark urine
  • Electrolyte derangement:
    • Hypokalaemia
    • Hyponatraemia
    • Ketonuria
  • Can result in Wernicke’s encephalopathy if not treated appropriately

đź’Š Management

1st Line Antiemetics

Offer one of the following oral antiemetics and reassess after 24–72 hours:

  • Cyclizine 
  • Promethazine 
  • Prochlorperazine 
  • Chlorpromazine 
  • Doxylamine/pyridoxine (Xonvea) – the only licensed treatment for nausea/vomiting in pregnancy (prescribe depending on local formulary)

2nd Line Options (if inadequate response), consider:

Switch to one of the following:

  • Metoclopramide – max 5 days (risk of extrapyramidal side effects)
  • Domperidone – max 7 days (risk of cardiac side effects)
  • Ondansetron – max 5 days; advise re. small increased risk of cleft lip/palate if used in 1st trimester

Combination Therapy

  • If monotherapy is ineffective:
    • Add a second agent rather than switching class
    • Some women may require 3 or more antiemetics in combination

3rd Line: Corticosteroids

  • Offer oral prednisolone 40–50 mg daily only if all antiemetic combinations fail
  • Taper to the lowest effective maintenance dose
  • Prescribe in addition to antiemetics
  • Monitor blood pressure and screen for diabetes mellitus during treatment

🧴 Additional Measures

  • IV/oral rehydration to correct dehydration and electrolytes
  • Thiamine (e.g. Pabrinex): to prevent Wernicke’s encephalopathy in prolonged vomiting
  • Consider hospital admission if oral intake inadequate or biochemical abnormalities present
  • Nutritional support if severe/prolonged: may require enteral or parenteral nutrition

đź“ť Exam Clues & Clinchers

  • Early pregnancy with severe vomiting, weight loss, and ketonuria → Think hyperemesis
  • Molar pregnancy or multiple gestation → Higher hCG → ↑ risk

đź”— Useful Links and References