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Zorluk: KolayDiagnostic Workup and Test Sequencing

A 45-year-old man is evaluated in the outpatient clinic for a three-day history of progressive left leg swelling and pain. He recently returned from a 12-hour international flight. His past medical history is unremarkable, and he takes no medications. Vital signs are stable. Physical examination reveals pitting edema, erythema, and marked tenderness along the deep venous system of the left calf. The left calf circumference is 5 cm larger than the right calf. Based on clinical criteria, the patient has a high pretest probability for a deep vein thrombosis. Which of the following is the most appropriate initial step in the diagnostic workup?

  1. A
    Plasma D-dimer assay
  2. B
    Computed tomography venography of the lower extremities
  3. Compression ultrasonography of the left lower extremityCevap
  4. D
    Magnetic resonance venography
  5. E
    Contrast venography

Cevap

Compression ultrasonography of the left lower extremity
In patients with a high pretest probability of deep vein thrombosis (DVT), the standard of care is to proceed directly to compression ultrasonography. This non-invasive test has high sensitivity and specificity for proximal DVT. Bypassing the D-dimer assay is appropriate because a negative D-dimer in a high-risk patient does not definitively rule out DVT, and a positive result would still dictate the need for an ultrasound.

Adım Adım Çözüm

1
Assess the patient's pretest probability for deep vein thrombosis based on the clinical presentation.
The patient has unilateral leg swelling, pitting edema, marked tenderness, and a recent history of prolonged immobilization (12-hour flight). The clinical scenario explicitly states the probability is high.
The diagnostic pathway for suspected deep vein thrombosis strictly depends on whether the pretest probability is low/intermediate versus high.
2
Determine the appropriate initial diagnostic test for a high-probability patient.
Compression ultrasonography is the required next step.
In high-risk patients, a D-dimer is not useful because a negative result cannot confidently rule out a thrombosis, and a positive result requires an ultrasound anyway. Therefore, diagnostic imaging is performed immediately.

Anahtar Kavram

Patients with a high pretest probability for deep vein thrombosis should undergo initial diagnostic evaluation with compression ultrasonography, bypassing the D-dimer assay.
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Diagnostic Workup and Test Sequencing

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