The most appropriate initial diagnostic test to evaluate suspected deep vein thrombosis (DVT)?

The most appropriate initial diagnostic test to evaluate suspected deep vein thrombosis (DVT)?

• A. Duplex ultrasound (compression ultrasound) of the leg
• B. D-dimer test alone
• C. CT venography
• D. MRI of the leg

Answer: (A)

Duplex ultrasound with compression of the leg veins is the best initial test for suspected DVT because it directly assesses whether a vein can be compressed; a noncompressible vein indicates a thrombus. This technique is quick, noninvasive, widely available, and gives immediate information about proximal veins where DVT has the most clinical consequence. D-dimer alone is not diagnostic because it’s nonspecific and elevated in many conditions, so it can rule in little by itself and cannot confirm DVT. CT venography and MRI are more invasive, costly, and less accessible as first-line tests, and they expose the patient to contrast and, in the case of CT, radiation. If ultrasound is negative but clinical suspicion remains, repeat imaging or alternative studies may be considered, but the initial evaluation is best served by compression duplex ultrasound.

Duplex ultrasound with compression of the leg veins is the best initial test for suspected DVT because it directly assesses whether a vein can be compressed; a noncompressible vein indicates a thrombus. This technique is quick, noninvasive, widely available, and gives immediate information about proximal veins where DVT has the most clinical consequence. D-dimer alone is not diagnostic because it’s nonspecific and elevated in many conditions, so it can rule in little by itself and cannot confirm DVT. CT venography and MRI are more invasive, costly, and less accessible as first-line tests, and they expose the patient to contrast and, in the case of CT, radiation. If ultrasound is negative but clinical suspicion remains, repeat imaging or alternative studies may be considered, but the initial evaluation is best served by compression duplex ultrasound.