When to start empirical anticoagulant therapy for pulmonary embolism (PE) in pregnancy?

When to Start Empirical Anticoagulation for Pulmonary Embolism in Pregnancy

Empirical anticoagulation should be initiated immediately in pregnant women with high or intermediate clinical probability of pulmonary embolism (PE) while diagnostic workup is in progress. 1

Clinical Probability Assessment

• Base the decision to start empirical anticoagulation on clinical probability assessment using either clinical judgment or a validated prediction rule 1
• For pregnant women with suspected PE, formal diagnostic assessment with validated methods is recommended 1
• D-dimer measurement and clinical prediction rules should be considered to rule out PE during pregnancy or post-partum period 1
• In pregnant patients with symptoms of DVT, venous compression ultrasonography should be considered to avoid unnecessary radiation 1

Immediate Management Algorithm

High Clinical Probability or Hemodynamic Instability:

• Initiate intravenous unfractionated heparin (UFH) without delay, including a weight-adjusted bolus injection 1
• For high-risk PE with hemodynamic instability, consider thrombolysis or surgical embolectomy 1
• Bedside echocardiography or emergency CTPA should be performed for diagnosis depending on availability and clinical circumstances 1

Intermediate Clinical Probability:

• Start therapeutic, fixed doses of low-molecular-weight heparin (LMWH) based on early pregnancy weight while awaiting diagnostic confirmation 1, 2
• Continue diagnostic workup with appropriate imaging (perfusion scintigraphy or CTPA with low-radiation dose protocol) 1

Low Clinical Probability:

• Consider D-dimer testing first; if negative, PE can be safely ruled out 1
• If D-dimer is positive, proceed with diagnostic imaging before starting anticoagulation 1

Choice of Anticoagulant

• LMWH is the preferred anticoagulant for pregnant women with confirmed PE 1, 2
• UFH may be considered as an alternative, particularly in situations requiring rapid reversal 2
• NOACs (apixaban, dabigatran, edoxaban, rivaroxaban) are contraindicated during pregnancy and lactation 1, 2

Important Considerations

• Therapeutic doses of LMWH should be based on early pregnancy weight and administered throughout pregnancy 2
• Do not insert a spinal or epidural needle within 24 hours of the last LMWH dose 1, 2
• For high-risk PE near delivery, UFH infusion should be converted from LMWH at least 36 hours prior to anticipated delivery 1
• UFH infusion should be stopped 4-6 hours prior to anticipated delivery 1
• Do not administer LMWH within 4 hours of removal of an epidural catheter 1

Duration of Treatment

• Anticoagulant treatment should be administered for at least 6 weeks after delivery with a minimum overall treatment duration of 3 months 1
• After delivery, heparin treatment may be replaced by vitamin K antagonists (VKAs) 1, 2
• VKAs can be given to breastfeeding mothers 1

Common Pitfalls to Avoid

• Delaying anticoagulation in high-risk situations while waiting for diagnostic confirmation 1
• Failure to adjust LMWH dosing based on weight changes during pregnancy 2
• Inadequate planning for labor and delivery anticoagulation management 2
• Using NOACs during pregnancy or lactation 1, 2

Multidisciplinary Approach

• A team of multidisciplinary colleagues should collaborate in planning ante-, peri-, and post-partum care pathways 1
• Close collaboration between obstetrician, anesthesiologist, and attending physician is recommended for peripartum management 2