Venous Thrombosis II: Clinical Manifestations and Diagnostic Studies

Superficial vein thrombosis (SVT) affects veins near the skin surface and presents with localized pain, tenderness, redness, and a palpable cord-like structure. Deep vein thrombosis (DVT) occurs in deeper veins and causes unilateral leg edema, pain, warmth, dilated superficial veins, and paresthesias. DVT is more dangerous because it can lead to pulmonary embolism, a life-threatening complication.

DVT presents with unilateral leg edema, pain, tenderness upon palpation, dilated superficial veins, a sense of fullness in the calf or thigh, warm skin, redness, and paresthesias. Patients may also experience systemic temperature elevation above 100.4°F. If the inferior vena cava is involved, both legs become edematous and cyanotic.

Laboratory tests measure coagulation markers including activated partial thromboplastin time (aPTT), international normalized ratio (INR), and prothrombin time (PT). Elevated D-dimer levels above 250 ng/mL and fibrin monomer complexes above 6.1 mg/L indicate thrombus formation and suggest venous thromboembolism, helping confirm diagnosis.

Duplex ultrasound combines compression with spectral and color Doppler imaging to assess vein compressibility and detect intraluminal filling defects. In normal findings, veins collapse with external pressure. Failure to collapse suggests a thrombus is present, making duplex ultrasound a primary noninvasive imaging study for venous thrombosis diagnosis.

Invasive imaging studies like computed tomography venography (CTV) with contrast evaluate veins in the pelvis, thighs, and calves and can be combined with CT angiography for comprehensive venous thromboembolism evaluation. Magnetic resonance venography (MRV) assesses blood flow through veins and distinguishes between acute and chronic thrombi, though it is less accurate for calf veins.

Untreated DVT can lead to pulmonary embolism (PE), a life-threatening condition where a clot dislodges and travels to the lungs, causing respiratory distress or sudden death. DVT may also progress to involve the superior vena cava, causing symptoms in the arms, neck, back, and face. Accurate assessment and diagnosis are crucial for preventing these serious complications.

SVT is typically less dangerous than DVT but can cause localized discomfort and lead to cellulitis or, rarely, clot extension into the deep venous system. DVT is more concerning due to its potential to cause life-threatening pulmonary embolism. Accurate diagnosis distinguishes these conditions and guides appropriate treatment to prevent serious complications.