Maternal Medicine - DVT & PE

Background

  • PE is the leading cause of maternal death, most occurring post-partum.
  • Hypercoaguable state begins early in pregnancy.
  • Thrombophilia screening is not sensible during pregnancy except under expert advice.
  • Pregnancy increases VTE risk x6, C-section x10-20.
  • Left-sided DVT is much more common (85%) than right-sided (15%).
  • Proximal DVT is much more common in pregnancy (72% of all DVT) than non-pregnancy (9%).

Diagnosis

  • Classical features are unreliable: leg oedema and pain are common in normal pregnancy.
  • High index of suspicion if chest pain or hypoxia.
  • For DVT:
    • Venography is the gold standard test, and involves negligible radiation exposure.
    • Doppler USS is more common, and a reasonable test.
    • D-dimer is not useful. False positives are common, and the high index of suspicion means that a negative result changes nothing.
  • For PE:
    • Perfusion scan is suggested as the first investigation.
    • CTPA is OK for the fetus, but may increase breast cancer risk. If breastfeeding, should discard milk for 24 hours.

Treatment

  • Higher dose LMWH: enoxaparin 1mg/kg bd, rather than 1.5mg/kd od.
  • Start treatment first if investigations may be delayed.
  • Some monitor anti-Xa levels.
  • Low risk of HIT, so no need to monitor platelets.
  • Convert to IV heparin around time of delivery.
  • Warfarin is safe during breastfeeding.