What would cause ecchymosis in the anterior hip or groin region in a patient with pain during active hip flexion, potential iliopsoas muscle pathology, and taking anticoagulant medications such as warfarin (coumarin) or aspirin (acetylsalicylic acid)?

Ecchymosis in the Anterior Hip/Groin Region: Anticoagulant-Related Iliopsoas Hemorrhage

In a patient with anterior hip/groin pain during active hip flexion and taking anticoagulants (warfarin or aspirin), the most likely cause of ecchymosis is spontaneous iliopsoas muscle hemorrhage, a potentially life-threatening complication that occurs in 12-14% of patients with bleeding disorders and is significantly increased by anticoagulant therapy. 1, 2, 3

Primary Mechanism: Anticoagulant-Induced Bleeding

Warfarin (Coumarin) Effects

• Warfarin inhibits vitamin K-dependent clotting factors (II, VII, IX, X) and anticoagulant proteins C and S, resulting in sequential depression of coagulation cascade over 72-96 hours. 4
• The drug has a narrow therapeutic index, and bleeding risk increases exponentially when INR exceeds 3.0-3.5. 5, 4
• Major bleeding is defined as clinically overt bleeding with hemoglobin decrease ≥2 g/dL, which commonly occurs with iliopsoas hematomas. 6, 2

Aspirin (Acetylsalicylic Acid) Contribution

• Aspirin inhibits platelet aggregation and causes gastric erosions, doubling bleeding risk when combined with other anticoagulants through both pharmacokinetic interactions and direct antiplatelet effects. 5, 4
• Approximately one-third of patients presenting with hip fractures take aspirin regularly, creating significant bleeding risk when combined with other thromboprophylactic medications. 1

Clinical Presentation of Iliopsoas Hemorrhage

Cardinal Symptoms

• Thigh, hip, and/or groin pain (present in nearly all cases) 2, 3
• Hip flexion contracture—the patient holds the hip in flexed position to minimize pain 2, 3
• Femoral nerve paresthesia in the distribution of the femoral nerve 2, 3, 7
• Hemoglobin drop >2 g/dL 2
• Pain aggravated by active hip flexion and hip extension 8, 9

Physical Examination Findings

• Abdominal tenderness may be present 3
• Quadriceps weakness (knee extensor weakness) due to femoral nerve compression 7, 9
• Visible ecchymosis in the anterior hip/groin region from blood tracking superficially 2, 3

Diagnostic Approach

Imaging Confirmation

• Ultrasonography confirms iliopsoas hematoma in all cases and should be the initial imaging modality. 3, 9
• Computed tomography (CT) demonstrates fluid collection in the iliopsoas bursa/muscle and displacement of the femoral nerve. 8, 7, 9
• MRI provides detailed soft tissue evaluation and can differentiate between bursitis and hematoma. 1, 9

Laboratory Assessment

• Check INR immediately—target should be <2 for surgery and <1.5 for neuraxial procedures. 1
• Complete blood count to assess hemoglobin drop (typically >2 g/dL). 2
• Coagulation studies to guide reversal therapy if needed. 1

Risk Factors Specific to This Scenario

Anticoagulant-Related Factors

• Warfarin therapy carries 3% annual risk of major bleeding with 0.6% case fatality rate. 1
• Combination of warfarin plus aspirin approximately doubles bleeding risk compared to warfarin alone. 5, 6
• High-intensity anticoagulation (INR 3.0-4.5) resulted in 53 major bleeding complications versus 6 on aspirin alone in the SPIRIT trial. 1

Patient-Specific Risk Factors

• Age ≥65 years increases bleeding risk. 4
• History of gastrointestinal bleeding or previous hemorrhage. 5, 4
• Renal insufficiency or anemia. 4
• Highly variable INRs. 4

Critical Pitfalls to Avoid

Delayed Recognition

• Patients typically wait 3.8 ± 4 days before seeking medical attention, allowing hematoma expansion and nerve compression. 2
• Do not dismiss groin pain in anticoagulated patients as simple musculoskeletal strain. 8, 7

Inadequate Anticoagulation Management

• For warfarin reversal in major bleeding with elevated INR, administer 4-factor prothrombin complex concentrate (25-50 U/kg IV) plus vitamin K 5-10 mg by slow IV infusion. 6
• Small amounts of vitamin K may be used to reverse warfarin effects to achieve INR <2 for surgery. 1
• Aspirin should be withheld during inpatient stay unless indicated for unstable angina or recent/frequent transient ischemic attacks. 1

Misdiagnosis of Iliopsoas Pathology

• Hip flexion pain with iliopsoas involvement can mimic FAI syndrome, labral tears, or bursitis—but ecchymosis strongly suggests hemorrhage rather than inflammatory pathology. 1
• Electromyography can confirm femoral neuropathy and determine lesion severity and location. 9

Treatment Implications

Conservative vs. Surgical Management

• Surgical drainage is indicated when symptoms are severe and disabling, particularly with femoral nerve palsy. 7
• Mean duration of therapy is 18.7 ± 11.9 days with hospitalization of 12.3 ± 9.1 days. 2
• Physical therapy should begin 6.0 ± 2.4 days after initiation of hemostatic therapy and last approximately 20 days. 3
• Ultrasonographic findings typically resolve within 3 months from initial episodes. 3

Recurrence Risk

• Low frequency of recurrent bleeding (2.8%) after appropriate treatment. 2
• Patients with inhibitors to clotting factors remain hospitalized significantly longer (19.1 ± 5.8 days vs. 7.6 ± 7.8 days). 2