What is the recommended VTE (Venous Thromboembolism) prophylaxis for a pregnant woman undergoing a C-section?

VTE Prophylaxis Before C-Section

For women undergoing cesarean section without additional risk factors, do not use pharmacologic thromboprophylaxis—early mobilization alone is sufficient. 1

Risk Stratification Framework

The decision to use VTE prophylaxis depends entirely on the presence of additional risk factors beyond the cesarean delivery itself:

Low-Risk Patients (No Additional Risk Factors)

• Early mobilization is the only recommended intervention for women undergoing cesarean section without additional thrombosis risk factors (Grade 1B). 1
• Pharmacologic prophylaxis is explicitly recommended against in this population due to bleeding risks that outweigh minimal VTE risk. 1

Intermediate-Risk Patients (≥1 Major OR ≥2 Minor Risk Factors)

Use either prophylactic LMWH or mechanical prophylaxis (sequential compression devices/elastic stockings) while hospitalized (Grade 2B). 1

Major risk factors include: 2

• Prior VTE
• Thrombophilia (particularly homozygous Factor V Leiden or prothrombin 20210A mutation)
• Active cancer
• Prolonged immobility

Minor risk factors include: 2

• Advanced maternal age (typically ≥35-45 years)
• Obesity (BMI ≥30)
• Multiparity (≥3 prior deliveries)
• Emergency cesarean section
• Prolonged labor before cesarean
• Preeclampsia
• Smoking

Specific prophylaxis options: 1, 2

• Prophylactic LMWH: Enoxaparin 40 mg subcutaneously once daily starting postoperatively
• Mechanical prophylaxis: Sequential compression devices applied before surgery and continued until fully ambulatory
• For patients with contraindications to anticoagulation (active bleeding, coagulopathy), use mechanical prophylaxis exclusively 1

Very High-Risk Patients (Multiple Persistent Risk Factors)

Combine prophylactic LMWH with elastic stockings and/or intermittent pneumatic compression rather than LMWH alone (Grade 2C). 1

This applies to women with multiple additional risk factors that persist into the puerperium, such as:

• Prior VTE plus obesity plus emergency cesarean 1
• Known thrombophilia plus family history of VTE plus prolonged immobility 1

Timing and Duration Considerations

Initiation

• Sequential compression devices should be applied before surgery and maintained until the patient is fully ambulatory. 2
• Prophylactic LMWH should be initiated postoperatively once hemostasis is assured, typically 6-12 hours after cesarean delivery if no increased bleeding risk exists. 3

Duration

• Standard duration: Continue prophylaxis while hospitalized until fully ambulatory. 1
• Extended prophylaxis: For selected high-risk patients with persistent risk factors after discharge, consider extending prophylaxis up to 6 weeks postpartum (Grade 2C). 1

Special Populations

Patients with Renal Impairment

• If creatinine clearance <30 mL/min, use unfractionated heparin instead of LMWH (typically 5,000 units subcutaneously every 8-12 hours). 2, 4
• UFH has a shorter half-life and is cleared by the reticuloendothelial system rather than kidneys. 5

Patients with Class III Obesity (BMI ≥40)

• Consider intermediate-dose enoxaparin (e.g., enoxaparin 40 mg subcutaneously twice daily or 0.5 mg/kg once daily) rather than standard prophylactic dosing (Grade 2C). 2

Patients Already on Therapeutic Anticoagulation

• For women receiving adjusted-dose LMWH therapy, discontinue LMWH at least 24 hours prior to planned cesarean section to allow for safe neuraxial anesthesia (Grade 1B). 1
• Resume therapeutic anticoagulation postoperatively once hemostasis is assured. 1

Common Pitfalls to Avoid

• Do not use prophylactic anticoagulation in low-risk cesarean patients—this increases bleeding risk without meaningful VTE reduction. 1
• Do not delay mechanical prophylaxis—sequential compression devices must be applied before surgery, not after. 2
• Do not use warfarin or direct oral anticoagulants (DOACs) for prophylaxis in the immediate postpartum period—LMWH is the agent of choice. 1, 6
• Do not forget to assess for persistent risk factors at discharge—patients with ongoing thrombophilia, obesity, or immobility may require extended prophylaxis. 1
• Do not administer LMWH within 12 hours of neuraxial anesthesia placement or within 4 hours of catheter removal—this increases spinal hematoma risk. 3

Institutional Implementation

The Society for Maternal-Fetal Medicine recommends that each institution develop a standardized VTE risk assessment protocol and prophylaxis bundle for all women undergoing cesarean delivery. 2 This should include:

• Mandatory risk factor assessment on admission 2
• Automatic order sets for mechanical prophylaxis 2
• Clear criteria triggering pharmacologic prophylaxis 2
• Discharge planning for extended prophylaxis when indicated 2