Hyperemesis Gravidarum

Overview – Hyperemesis Gravidarum

Hyperemesis gravidarum is a severe and debilitating form of nausea and vomiting that occurs during pregnancy, most often in the first trimester. While mild nausea affects nearly all pregnant women to some degree, hyperemesis gravidarum is characterised by intractable vomiting, dehydration, electrolyte imbalances, and weight loss. It requires prompt identification and supportive management to prevent maternal and fetal complications.

Definition

• Severe, persistent nausea and vomiting during pregnancy that results in:
  • Weight loss >5% of pre-pregnancy body weight
  • Dehydration
  • Electrolyte disturbances
  • Often necessitates hospitalisation

Aetiology

• Believed to result from rapidly rising levels of human chorionic gonadotropin (hCG) and oestrogen
• May be more likely in:
  • Multiple gestations
  • Molar pregnancies
  • First pregnancies

Clinical Features

• Onset: Typically in first trimester
• Nausea and vomiting that is:
  • Severe and intractable
  • Not responsive to simple dietary or pharmacologic changes
• May lead to:
  • Poor oral intake
  • Fatigue
  • Light-headedness
  • Signs of dehydration

Investigations

Rule Out Other Causes

• Gastrointestinal:
  • Gastritis
  • Gallstones
• Genitourinary:
  • Pyelonephritis / urinary tract infection
• Endocrine:
  • Thyrotoxicosis
• Obstetric:
  • HELLP syndrome
  • Multiple pregnancy (USS)

Blood Tests

• Full Blood Examination (FBE)
• Electrolytes
• Renal function / Creatinine
• Liver Function Tests (LFTs)

Imaging

• Ultrasound to assess for:
  • Multiple gestation
  • Anatomical abnormalities
  • Molar pregnancy
  • Gallstones

Management

General Principles

• Rule out differential diagnoses (e.g. infection, endocrine)
• Encourage:
  • Frequent small meals
  • Oral electrolyte solutions (e.g. Hydralyte, Powerade)
  • Ginger tablets
  • Trial cessation of prenatal vitamins

Pharmacological

• First-line:
  • Doxylamine + Pyridoxine (Vitamin B6)
• Alternatives:
  • Dimenhydrinate
  • Metoclopramide
  • Vitamin B6 lozenges

Severe Cases

• Thiamine supplementation (to prevent Wernicke’s encephalopathy)
• Hospital admission for:
  • Intravenous fluid and electrolyte correction
  • Monitoring of input/output
• If refractory:
  • Total Parenteral Nutrition (TPN) in catabolic states

Complications

• Electrolyte disturbances (e.g. hypokalaemia, metabolic alkalosis)
• Dehydration
• Mallory-Weiss tears (due to repeated vomiting)
• Wernicke’s encephalopathy (due to thiamine deficiency)
• Intrauterine Growth Restriction (IUGR) due to maternal malnutrition

Differential Diagnosis

• Urinary tract infection / pyelonephritis
• Gastroenteritis or gastritis
• Cholelithiasis / gallstones
• Molar pregnancy
• Multiple gestation
• Thyrotoxicosis
• HELLP syndrome
• Diabetic ketoacidosis (especially in Type 1 diabetes)

Summary – Hyperemesis Gravidarum

Hyperemesis gravidarum is a serious condition that goes beyond the typical nausea of pregnancy, requiring careful clinical evaluation and targeted supportive therapy. Early recognition and multidisciplinary care are essential to avoid significant maternal and fetal complications. For a broader context, see our Obstetrics Overview page.