Blood Tests for Easy Bruising and Bleeding Gums
For patients presenting with easy bruising and bleeding gums, the recommended initial laboratory evaluation should include a complete blood count with platelet count, prothrombin time (PT), activated partial thromboplastin time (aPTT), fibrinogen, and a von Willebrand factor (VWF) screening panel. 1
Initial Laboratory Evaluation
Complete blood count (CBC) with platelet count
- Identifies thrombocytopenia (platelet count <150 × 10³/μL)
- Assesses for anemia which may accompany bleeding disorders
- Evaluates platelet size and morphology on peripheral smear
Coagulation studies
- Prothrombin time (PT) - evaluates extrinsic pathway
- Activated partial thromboplastin time (aPTT) - evaluates intrinsic pathway
- Thrombin time (TT) - detects fibrinogen disorders or heparin presence
- Fibrinogen level - identifies hypofibrinogenemia
Von Willebrand factor panel
- VWF antigen (VWF:Ag)
- VWF ristocetin cofactor activity (VWF:RCo)
- Factor VIII coagulant activity (FVIII:C)
- VWF:RCo/VWF:Ag ratio (ratio <0.5-0.7 suggests qualitative defects) 1
Interpretation of Results
Normal PT, prolonged aPTT:
- Suggests disorders of the intrinsic pathway:
Prolonged PT, normal aPTT:
- Suggests disorders of the extrinsic pathway:
- Factor VII deficiency
- Vitamin K deficiency (early)
- Liver disease (early) 2
Both PT and aPTT prolonged:
- Multiple factor deficiencies
- Liver disease
- Disseminated intravascular coagulation (DIC)
- Vitamin K deficiency 3
Normal PT and aPTT with bleeding symptoms:
- Platelet function disorders
- Von Willebrand disease (most common inherited bleeding disorder)
- Factor XIII deficiency 3, 2
Thrombocytopenia (low platelet count):
- Mild: 50-150 × 10³/μL - generally asymptomatic
- Moderate: 20-50 × 10³/μL - may have mild skin manifestations (petechiae, purpura)
- Severe: <10 × 10³/μL - high risk of serious bleeding 4
Advanced Testing
If initial tests suggest a specific disorder or are inconclusive despite clinical suspicion:
For suspected von Willebrand disease:
- VWF multimer analysis
- VWF collagen binding assay (VWF:CB)
- Ristocetin-induced platelet aggregation (RIPA) 1
For suspected platelet function disorders:
- Platelet function assays
- Bleeding time (less commonly used now)
- Platelet aggregation studies 3
For suspected coagulation factor deficiencies:
- Specific factor assays (Factors II, V, VII, VIII, IX, X, XI, XIII)
- Mixing studies to differentiate factor deficiencies from inhibitors 3
Clinical Considerations
Ensure proper sample collection to avoid pseudothrombocytopenia (collect blood in tubes containing heparin or sodium citrate if suspected) 4
Review medication history for drugs that affect platelet function (aspirin, NSAIDs, anticoagulants) or cause drug-induced thrombocytopenia 4
Consider underlying conditions that may cause acquired bleeding disorders:
- Lymphoproliferative disorders
- Myeloproliferative disorders
- Cardiovascular conditions
- Autoimmune diseases
- Malignancies 1
If immune thrombocytopenia is suspected, additional testing for autoimmune markers may be warranted 5
When to Refer to Hematology
Hematology consultation is recommended when:
- Initial evaluation indicates a bleeding disorder
- Suspicion remains high despite normal laboratory results
- Complex cases requiring specialized testing
- Patients requiring specialized management of identified bleeding disorders 2
Common Pitfalls to Avoid
- Failing to collect samples before transfusions or hemostatic treatments
- Not considering acquired von Willebrand syndrome in patients with no prior bleeding history 1
- Overlooking medication effects on platelet function or coagulation
- Misinterpreting isolated laboratory abnormalities without clinical correlation
- Not repeating abnormal tests to confirm findings