Table 1.
Overview of the Similarities and Differences Between a Seroma and Hematoma in the Setting of TJA
| Seroma | Hematoma | |
|---|---|---|
| COMPOSITION | Serous exudate (lymph, fibrin, WBC, cytokines) Scant Blood Products | Majority of Blood products, (RBC, fibrin, platelets, cytokines) |
| TIMEFRAME TO APPEARANCE | 2 weeks or more | 2–7 days |
| ASSOCIATED LABS | Loosely associated with Nutrition labs* | Declining hemoglobin and Hematocrit |
| PHYSICAL EXAM FINDINGS | Fluid Wave | Firm Mass; Ecchymosis |
| COMMON LOCATION(S) | Subcutaneous tissue superficial to muscle fascia | Subcutaneous tissue superficial to muscle fascia; superficial to muscle by deep to fascia; intramuscular; intra-articular |
| ULTRASOUND | Anechoic | Hyperechoic |
| CT SCAN | 0–20 Hounsfield Units | Hounsfield Units: 30–45 (uncoagulated) 60–100 (coagulated) *CT Angiography to help identify bleeding vessel |
| MRI | Hypointense T1 Hyperintense T2 & STIR Septations, fluid-fluid levels |
Hyperintense T1 & T2 & STIR |
| APPEARANCE OF ASPIRATION FLUID | Translucent yellow-orange serous | Early hematoma dark red *Difficult to aspirate mature coagulated hematoma |