What bleeding parameters should be investigated in a patient with excessive hematoma and ecchymosis 2 days post-Coronary Artery Bypass Grafting (CABG) who is on aspirin (acetylsalicylic acid)?

Bleeding Parameters to Investigate Post-CABG with Aspirin

In a patient with excessive hematoma and ecchymosis 2 days post-CABG on aspirin, you should immediately obtain: complete blood count with platelet count, PT/INR, aPTT, fibrinogen level, and platelet function testing (if available), while recognizing that aspirin alone typically causes only modest bleeding increases and other factors are likely contributing. 1

Initial Laboratory Assessment

Essential First-Line Tests

• Complete Blood Count (CBC) with platelet count: Assess for thrombocytopenia, anemia severity, and hematocrit to quantify blood loss 1
• Prothrombin Time (PT/INR): Rule out coagulopathy from liver dysfunction, vitamin K deficiency, or unrecognized warfarin use 1
• Activated Partial Thromboplastin Time (aPTT): Detect intrinsic pathway defects, heparin effect, or factor deficiencies 1
• Fibrinogen level: Identify consumptive coagulopathy or dilutional effects from massive transfusion 1

Critical Context About Aspirin

Aspirin monotherapy causes only modest increases in post-CABG bleeding (approximately 130 mL additional blood loss) and should not cause the degree of bleeding you're describing. 2 This means you must look beyond aspirin as the sole culprit.

Secondary Investigations Based on Clinical Suspicion

If Platelet Dysfunction is Suspected

• Platelet function testing (VerifyNow Aspirin assay or similar): Aspirin-sensitive patients have significantly higher blood loss (555 mL vs 406 mL at 12 hours) compared to aspirin-resistant patients 3
• Bleeding time (if platelet function testing unavailable): Though less specific, can indicate platelet dysfunction 1

If Recent P2Y12 Inhibitor Use is Possible

This is critical because the patient may have been on dual antiplatelet therapy that was incompletely discontinued:

• Verify medication history carefully: Clopidogrel should be stopped ≥5 days before CABG, prasugrel ≥7 days, and ticagrelor ≥3 days 1
• If clopidogrel was stopped <5 days preoperatively: This dramatically increases bleeding risk (9.6% major bleeding vs 6.3% when stopped ≥5 days) 1
• Combined aspirin + clopidogrel within 7 days: Associated with 2.2-fold increased risk of excessive transfusion (OR 2.2,95% CI 1.1-4.3) 4

Additional Coagulation Studies

• Thromboelastography (TEG) or Rotational Thromboelastometry (ROTEM): Provides comprehensive assessment of clot formation and fibrinolysis in real-time 1
• D-dimer and fibrin degradation products: If disseminated intravascular coagulation (DIC) is suspected 1
• Factor assays (VIII, IX, XI): If congenital bleeding disorder suspected based on history 1

Common Pitfalls to Avoid

Don't Assume Aspirin is the Primary Culprit

Aspirin doses ≤100 mg daily may not significantly increase postoperative bleeding at all. 2 The 2024 ESC guidelines note that aspirin should be continued until surgery and restarted within 24 hours, indicating its bleeding risk is considered acceptable. 1

Don't Miss Occult P2Y12 Inhibitor Use

• Patients may not report clopidogrel/ticagrelor use accurately 1
• Even 1-4 days after clopidogrel discontinuation increases transfusion requirements without necessarily increasing life-threatening bleeding 1

Don't Overlook Surgical/Technical Causes

Excessive hematoma and ecchymosis 2 days post-op may indicate:

• Inadequate surgical hemostasis 1
• Chest tube malfunction or clotting 1
• Developing pericardial effusion/tamponade 1

Consider Heparin Rebound

• Protamine reversal may be incomplete 1
• Check aPTT to assess for residual heparin effect 1

Algorithmic Approach to Investigation

Step 1: Obtain CBC, PT/INR, aPTT, fibrinogen immediately 1

Step 2: Review medication reconciliation for any P2Y12 inhibitors within 7 days of surgery 1

Step 3: If basic coagulation studies are normal and bleeding is disproportionate, obtain platelet function testing 3

Step 4: If fibrinogen is low or aPTT prolonged, consider TEG/ROTEM for comprehensive assessment 1

Step 5: Ensure surgical causes are excluded with physical examination and imaging (chest X-ray, echocardiogram if tamponade suspected) 1

Management Implications

While investigating, do not discontinue aspirin unless life-threatening bleeding occurs, as aspirin is recommended to be restarted within 24 hours post-CABG for graft patency. 1, 5 The bleeding is likely multifactorial rather than aspirin-related alone. 2