Common diagnostic tools
for DVT include:

• D-dimer test
• Duplex Doppler ultrasound
• Venography
• MRI
• CT scan

Diagnosing DVT

In addition to a physical exam and medical history, other tests are usually necessary to make a definite diagnosis of DVT. Your healthcare provider will determine which tests are appropriate for you. The most commonly prescribed tests include:

• D-dimer test: this blood test is used to measure elevated levels of a type of plasma present when a thrombus is forming.
• Duplex Doppler ultrasound: a noninvasive test that shows how blood is flowing through the vessels and also measures the speed of blood flow. Duplex ultrasound is also useful for estimating the diameter of a blood vessel and how much obstruction, if any, is present.
• Venography: x-rays taken after dye is injected into a vein to study areas of normal and abnormal blood flow.
• MRI (magnetic resonance imaging): a noninvasive procedure that uses a magnetic field to provide three-dimensional images of internal tissues and organs.
• CT scan (computed tomography): an imaging technique that allows for cross-sectional views of body organs and tissues.