What would cause a large hematoma from a small IV line on the arm of a patient with a slightly elevated white blood cell count and normal red blood cell count, hemoglobin, and hematocrit?

Hematoma Formation from Small IV Line

The most likely cause of a large hematoma from a small IV line in this patient is inadequate direct pressure application after IV removal or traumatic venipuncture technique, not a coagulation disorder—the laboratory values show normal hemostasis parameters.

Laboratory Value Interpretation

The patient's complete blood count reveals:

• WBC 14.3: Mildly elevated, suggesting possible inflammation or stress response, but not indicative of coagulation dysfunction 1
• RBC 5.91, Hemoglobin 16.6, Hematocrit 50.9: All elevated together, consistent with either relative polycythemia from dehydration or true polycythemia 2, 3
• No coagulation abnormalities: These CBC parameters do not assess platelet function, clotting factors, or bleeding tendency 4

The elevated hematocrit (50.9) most likely represents dehydration-induced hemoconcentration, which actually increases blood viscosity rather than causing bleeding 2. This patient's blood should clot more readily, not less 3.

Primary Causes of IV-Related Hematomas

Technical Factors (Most Common)

• Inadequate compression after IV removal: Failure to apply firm, direct pressure for 3-5 minutes is the leading cause of post-venipuncture hematomas 5
• Traumatic insertion technique: Through-and-through puncture of the vein, multiple insertion attempts, or catheter movement within the vein damages vessel walls 5
• Premature patient movement: Flexing the arm or removing pressure dressing too early allows bleeding into surrounding tissue 5

Patient-Related Factors to Assess

Critical medication history (these are the actual coagulation concerns):

• Antiplatelet agents: Aspirin causes low bleeding risk, but P2Y12 antagonists (clopidogrel, prasugrel, ticagrelor) significantly increase hematoma formation 5
• Anticoagulants: Warfarin, heparin, low-molecular-weight heparin, or direct oral anticoagulants (dabigatran, rivaroxaban, apixaban) markedly increase bleeding risk 5
• NSAIDs: Ibuprofen, naproxen, and other NSAIDs impair platelet function 5

Other risk factors:

• Fragile vessels: Elderly patients, chronic steroid use, or sun-damaged skin have increased vessel fragility 5
• Renal disease: Causes platelet dysfunction despite normal platelet counts 5

What This Patient Does NOT Have

The CBC values provided do not indicate:

• Thrombocytopenia: No platelet count provided, but hematoma from low platelets requires counts <50 × 10⁹/L for spontaneous bleeding 5
• Coagulation factor deficiency: Would require PT/INR, aPTT, or fibrinogen testing—not assessed by basic CBC 5
• Hemolysis or bleeding disorder: Normal hemoglobin and hematocrit argue against ongoing blood loss 6

Diagnostic Approach

Immediate assessment:

1. Medication reconciliation: Specifically ask about aspirin, clopidogrel, warfarin, DOACs, NSAIDs, and herbal supplements (ginkgo, garlic, ginger) 5
2. Bleeding history: Prior excessive bleeding with dental work, surgery, or other venipunctures suggests underlying disorder 5
3. Hematoma characteristics: Size, expansion rate, and associated pain guide urgency 5

Laboratory evaluation if clinically indicated:

• Platelet count: Should be >75 × 10⁹/L for adequate hemostasis in bleeding patients 5
• PT/INR and aPTT: Assess clotting factor function if on anticoagulants or unexplained bleeding 5
• Fibrinogen level: More sensitive than PT/aPTT for detecting coagulopathy; should be >1.5 g/L 5

Management Recommendations

For current hematoma:

• Apply firm, continuous pressure for minimum 10 minutes without checking 5
• Elevate the affected arm above heart level 5
• Apply ice packs for 20 minutes every 2 hours for first 24 hours 5
• Monitor for compartment syndrome: Increasing pain, paresthesias, or pallor require urgent surgical evaluation 5

Prevention for future venipuncture:

• Hold direct pressure for 5 minutes minimum after IV removal, 10 minutes if on antiplatelet/anticoagulant therapy 5
• Use smallest gauge catheter necessary for clinical indication 5
• Avoid excessive probing during insertion; limit to 2 attempts per site 5
• Consider platelet transfusion before procedures if on P2Y12 antagonists with active bleeding 5

Critical Pitfall

Do not assume coagulopathy based on hematoma alone—the vast majority of IV-related hematomas result from inadequate compression technique, not bleeding disorders 5. The elevated hematocrit in this patient suggests hemoconcentration, which would reduce bleeding tendency, not increase it 2, 3. Only pursue extensive coagulation testing if there is documented anticoagulant use, personal/family bleeding history, or multiple unexplained bleeding episodes 5.