When can aspirin (acetylsalicylic acid) be restarted after a subdural hematoma has resolved?

When to Restart Aspirin After Subdural Hematoma

Aspirin should be discontinued immediately upon diagnosis of subdural hematoma and can be restarted at 7-10 days for patients with very high thromboembolism risk, or at 1-2 weeks for most other patients, after confirming hemorrhage stability on brain imaging. 1

Immediate Management

• All antiplatelet agents, including aspirin, must be discontinued immediately upon diagnosis of subdural hematoma to prevent hematoma expansion 2, 1
• The acute period of highest risk for hematoma expansion is the first 1-2 weeks after hemorrhage 2, 1
• Obtain baseline brain imaging (CT or MRI) to document the hemorrhage extent 1

Risk Stratification Before Restarting

High Thromboembolism Risk (Consider Earlier Restart at 7-10 Days)

• Mechanical heart valves - these patients have the highest thrombotic risk 2, 1
• Atrial fibrillation with CHADS2 score ≥4 1
• Recent acute coronary syndrome or coronary stent placement (especially within 6 months) 2
• History of prior stroke or TIA while off antiplatelet therapy 2

High Hemorrhage Recurrence Risk (Consider Delaying or Avoiding Restart)

• Lobar location of subdural hematoma - suggests possible cerebral amyloid angiopathy with higher rebleeding risk 2, 1
• Multiple microbleeds on MRI - indicates underlying microangiopathy 2, 1
• Elderly patients with lobar hemorrhage - particularly high risk for amyloid angiopathy 1
• Large residual subdural hematoma on imaging - 62.5% rebleeding risk if large remnant present 3

Timing Algorithm

For Very High Thromboembolism Risk Patients:

• Restart aspirin at 7-10 days after the original hemorrhage 1
• Obtain repeat brain imaging before restarting to confirm hemorrhage stability 1
• This applies to mechanical heart valves and high CHADS2 score atrial fibrillation 1

For Standard Risk Patients:

• Wait at least 1-2 weeks before restarting aspirin 2, 1
• Confirm hemorrhage stability with repeat CT or MRI before restarting 1
• Research data shows median restart time of 2-4 weeks is commonly used 4

For High Hemorrhage Risk Patients:

• Wait 3-4 weeks or longer before considering restart 2
• For lobar hemorrhages with suspected amyloid angiopathy, consider avoiding restart entirely or using alternative strategies 2, 1
• Do not restart if large residual subdural hematoma persists - 82.1% of patients in one study waited until complete resolution 3

Special Considerations

Chronic Subdural Hematoma (Post-Surgical):

• Meta-analysis shows resuming antithrombotics does not increase hemorrhagic complications (14.8% vs 18.6%, p=0.591) but significantly reduces thromboembolism (2.9% vs 6.8%, p<0.001) 5
• Early resumption (<2 weeks) shows similar hemorrhagic risk to late resumption 5
• However, restarting with residual hematoma carries 41.2% rebleeding risk overall 3

Hemorrhagic Transformation of Ischemic Stroke:

• Aspirin may be continued if the hemorrhagic transformation is asymptomatic and minimal, depending on the underlying indication 2, 1
• This represents a different pathophysiology than primary subdural hematoma 2

Critical Pitfalls to Avoid

• Never delay obtaining repeat imaging before restart - clinical assessment alone is insufficient 1
• Do not restart both antiplatelet agents simultaneously if patient was on dual therapy - the thrombotic risk can be managed with aspirin alone initially 2
• Avoid restarting if any residual subdural collection remains visible unless thrombotic risk is extremely high (mechanical valve) 3
• Do not use higher aspirin doses - standard low-dose aspirin (81 mg) is appropriate when restarting 2

Documentation Requirements

• Document the specific indication for aspirin (coronary disease, stroke prevention, etc.) 4
• Record the thrombotic risk assessment (CHADS2 score, valve type, stent timing) 1
• Confirm imaging shows hemorrhage stability or resolution before restart 1
• Note any high-risk features for rebleeding (lobar location, microbleeds, amyloid angiopathy) 2, 1