What to do with enoxaparin (low molecular weight heparin) 30 mg injection in a patient with a recent subdural hemorrhage?

Management of Enoxaparin 30 mg in a Patient with Recent Subdural Hemorrhage

Immediately discontinue the enoxaparin 30 mg injection and do not restart prophylactic-dose anticoagulation in this patient with a recent subdural hemorrhage. 1

Immediate Action Required

Stop the enoxaparin immediately – The Neurocritical Care Society and Society of Critical Care Medicine explicitly recommend discontinuing low molecular weight heparin (LMWH) when intracranial hemorrhage is present or suspected. 1 This is a Good Practice statement that applies universally to all patients with any form of intracranial bleeding, including subdural hemorrhage.

Reversal Decision Algorithm

The decision to reverse prophylactic enoxaparin depends on the dose and clinical context:

• For prophylactic doses (like 30 mg): Routine reversal is NOT recommended unless the aPTT is significantly prolonged. 1 The 30 mg dose is a standard prophylactic regimen, not therapeutic dosing.

• For therapeutic doses: If this were a therapeutic dose (1 mg/kg twice daily), reversal with protamine would be strongly recommended. 1

Check an aPTT immediately – If the aPTT is significantly prolonged despite the prophylactic dose, consider reversal with protamine sulfate. 1 This is particularly important if:

• The patient has renal insufficiency (enoxaparin accumulates) 2
• There is evidence of hemorrhage expansion on imaging 1
• The patient is hemodynamically unstable 3

Protamine Reversal Protocol (If Indicated)

If reversal is deemed necessary based on prolonged aPTT or clinical deterioration:

• Dosing for enoxaparin 30 mg:

  • If given within 8 hours: administer 30 mg protamine (1 mg protamine per 1 mg enoxaparin, maximum 50 mg single dose) 1, 4
  • If given within 8-12 hours: administer 15 mg protamine (0.5 mg protamine per 1 mg enoxaparin) 1, 4
  • If >12 hours since last dose: protamine likely not needed 1

• Administration technique: Give by slow IV injection over 10 minutes to minimize hypotension risk. 1, 4

• Monitor for adverse reactions: Watch for hypotension, bradycardia, and anaphylactoid reactions, especially in patients with fish allergies or prior protamine exposure. 4

Critical Monitoring

Obtain urgent head CT to assess for:

• Subdural hemorrhage expansion 5
• New intracranial bleeding 6, 7
• Mass effect requiring neurosurgical intervention 8

The literature documents multiple cases of delayed subdural hematomas and hemorrhage expansion in patients receiving even prophylactic enoxaparin after head trauma. 6, 7 One case series reported 3 acute subdural hematomas related to therapeutic enoxaparin doses that resulted in death or severe neurological disability. 7

Alternative VTE Prophylaxis

Switch to mechanical prophylaxis immediately:

• Apply intermittent pneumatic compression (IPC) devices to both lower extremities within 24 hours 1
• Use thigh-high IPC devices, which are recommended for high-risk immobile patients 1
• Continue IPC until the patient becomes independently mobile or for up to 30 days 1
• Assess skin integrity daily while using IPC 1

Do NOT use anti-embolism stockings alone – these are ineffective for post-stroke VTE prophylaxis. 1

When to Consider Restarting Pharmacologic Prophylaxis

Pharmacologic VTE prophylaxis should only be reconsidered after:

• Documented stable head CT for at least 48 hours (some centers use 72 hours) 5
• Neurosurgical clearance if applicable
• Resolution of any coagulopathy
• Careful risk-benefit assessment given the patient's recent subdural hemorrhage

A 2025 study demonstrated that weight-based enoxaparin initiated 48 hours after stable head CT resulted in only 1.6% intracranial hemorrhage expansion in trauma patients with intracranial hemorrhage. 5 However, this patient already has a subdural hemorrhage while on enoxaparin, making them higher risk.

Special Considerations and Pitfalls

Renal function matters: If this patient has renal insufficiency (CrCl <30 mL/min), enoxaparin accumulates significantly, increasing bleeding risk 2.25-fold. 2 Even prophylactic doses can reach therapeutic levels in severe renal failure. 2

Age considerations: Elderly patients have higher bleeding risk with enoxaparin. 2 The FDA label documents that major bleeding complications occur in 2-4% of surgical patients receiving prophylactic enoxaparin. 9

Cerebral atrophy increases risk: Infants and patients with diffuse brain injury or cerebral atrophy have accentuated risk of intracranial hemorrhage from enoxaparin. 8 If this patient has underlying brain atrophy, the risk-benefit ratio strongly favors avoiding anticoagulation.

Do not switch to unfractionated heparin: Switching between enoxaparin and UFH increases bleeding risk. 2 If therapeutic anticoagulation becomes absolutely necessary later (e.g., for acute DVT/PE), this requires careful multidisciplinary discussion.