🔑 Key Learning

  • Pregnancy is a hypercoagulable state, increasing VTE risk; D-dimer is not useful in pregnancy
    • 1st line treatment: LMWH
  • Thyrotoxicosis: propylthiouracil in first trimester, switch to carbimazole for 2nd/3rd trimester. 
  • Obstetric cholestasis presents with itching, jaundice and raised bile acids; risk of stillbirth increases with bile acid levels
  • Acute fatty liver of pregnancy presents with hepatitis and very high ALT; prompt delivery is the treatment
  • Pruritic rashes include
    • Polymorphic eruption - pink papules and urticarial plaques, often within stretch marks
    • Pemphigoid gestationis - autoimmune blistering

🩸 Venous Thromboembolism in Pregnancy

Pathophysiology

  • Increased clotting factors (VII, VIII, X, fibrinogen)
  • Decreased protein S
  • Venous stasis from IVC compression

Investigations

  • Do not use D-dimer - will be raised anyway due to pregnancy 
  • Suspected DVT: compression duplex ultrasound
  • Suspected PE:
    • If DVT symptoms present → duplex US
      • If positive → treat as PE without CTPA (can avoid radiation risk)
    • If no DVT symptoms → CTPA or V/Q after discussion
      • CTPA: increased breast cancer risk (~10% increase)
      • V/Q: increased childhood cancer risk

Management

  • First-line: subcutaneous LMWH (e.g. enoxaparin)

🧠 Thyroid Problems in Pregnancy

Thyrotoxicosis

  • First trimester: propylthiouracil (due to teratogenicity of carbimazole)
  • Second and third trimester: switch to carbimazole (due to hepatotoxicity risk of PTU)
  • Aim: keep maternal thyroxine in upper third of normal

Hypothyroidism

  • Monitor TSH every trimester and 6–8 weeks post-partum
  • Increase levothyroxine dose by ~50% during pregnancy

🧴 Biliary Problems in Pregnancy

Obstetric Cholestasis (Intrahepatic Cholestasis of Pregnancy)

Timing

  • Typically third trimester

Diagnosis

  • Itching with elevated bile acids ≥19 µmol/L

Clinical Features

  • Generalised pruritus (palms and soles)
  • Jaundice, dark urine

Complications and Delivery Timing

  • Mild (19–39): background stillbirth risk → aim delivery by 40 weeks
  • Moderate (40–99): increased risk stillbirth after 38 weeks → delivery at 38–39 weeks
  • Severe (≥100): higher risk stillbirth→ consider delivery at 35–36 weeks

Management

  • No pharmacological treatments reduce adverse outcomes or bile acid levels
  • Ursodeoxycholic acid not routinely offered (removed in most recent guideline)
  • Symptom relief: emollients, chlorphenamine

Acute Fatty Liver of Pregnancy (AFLP)

Pathophysiology

  • Acute hepatic failure from fat accumulation in hepatocytes

Timing

  • Most common in third trimester

Clinical Features

  • Abdominal pain, nausea, vomiting, jaundice, ascites
  • ALT often > 500
  • Thrombocytopenia suggests HELLP instead

Management

  • Urgent delivery

🌡️ Rashes in Pregnancy

Polymorphic Eruption of Pregnancy (PEP)

Clinical Features

  • Also known as pruritic urticarial papules and plaques of pregnancy (PUPPP)
  • Intensely itchy, third trimester rash
  • Starts in abdominal striae as pink papules → urticarial plaques
  • May spread to trunk and limbs
  • Resolves after delivery
Left side view of the abdomen at nearly 36 weeks' gestation, showing the papules and plaques of PUPPP.
Frontal view of the abdomen at nearly 36 weeks' gestation, on which the papules and plaques of PUPPP can clearly be seen

Management

  • Antihistamines
  • Topical corticosteroids (oral if severe)

Pemphigoid Gestationis

Pathophysiology

  • An autoimmune, blistering rash of pregnancy 
  • An IgG autoantibody (called PG factor) develops and targets BP-180 proteins within the basement membrane between the epidermis and dermis.

Clinical Features

  • Starts around umbilicus in second or third trimester
  • Urticarial rash → tense fluid-filled blisters
  • May spread to trunk, limbs, buttocks

Management

  • Topical corticosteroids if mild
  • Systemic corticosteroids if severe

📝 Exam Clues & Clinchers

  • Pregnancy + leg swelling → suspect DVT → duplex US
  • Suspected PE + DVT symptoms → US first; if positive, no need to do CTPA
  • Hyperthyroid in pregnancy → PTU in first trimester, switch to carbimazole later
  • Itchy palms/soles + raised bile acids in late pregnancy → obstetric cholestasis
  • ALT > 500 + third trimester + acute hepatitis signs → acute fatty liver
  • Umbilical-centred itchy blistering rash → think pemphigoid gestationis
  • Very itchy rash in striae, no blisters → think polymorphic eruption

🔗 Useful Links and References