VTE in pregnancy

Question 1

Outline an intrapartum plan for a woman on therapeutic LMWH:

Answer 1

• Plan IOL at 39/40 if no other indication:
  
  • Stop LMWH 24 hours prior.
  • If very high risk for clot can have IV UFH.
• Surgical considerations:
  
  • Abdo and rectus drains
  • Interrupted sutures or staples
• If spontaneous labour:
  
  • Stop LMWH when labour starts.
  • Monitor APPT
  • Can attempt protamine sulfate reversal if APTT prolonged close to delivery.
• Rules around regional anaesthesia:
  
  • Stop IV UFH 6 hours before.
  • Stop therapeutic LMWH 24 hours before.
  • Do not give LMWH for 4 hours after.
  • Do not remove epidural catheter <12 hours after dose.

Question 2

Counsel patient about risks and benefits of CTPA

Answer 2

Risks:

• Significantly more radiation exposure to breast tissue than VQ scan

Benefits:

• Low radiation dose to fetus
• Quick and readily available
• Utility if abnormal CXR: can diagnose pneumonia, pulmonary oedema, aortic dissection
• Can breastfeed

Question 3

Counsel patient about risks and benefits of VQ scan:

Answer 3

Risks:

• Slightly increased risk of childhood cancer
• Unable to breastfeed for 12 hours after scan.
• Less accurate if CXR abnormal

Benefits:

• Substantially less radiation to breast tissue
• Good at diagnosing peripheral PE
• Less prone to suboptimal image quality/artefacts.

Question 4

What is the dosing for therapeutic LMWH and how long should it continue for?

Answer 4

LMWH 1.5 mg/kg sc once daily using pre-pregnancy or early pregnancy weight.

Adjust lower dose if CrCl <30 mL/min

Duration: at least 3 months total duration and at least up to 6 weeks postpartum.