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'''Deep vein thrombosis''' (DVT) is a form of [[venous thromboembolism]] which occurs in deep veins, most commonly in the legs or groin. Its main importance is the risk of the deep venous thrombosis dislodging and traveling to the lungs, causing [[pulmonary embolism]] (PE). DVT mostly affects the distal deep veins, but may affect the larger, proximal veins as well, including the iliac, femoral, or popliteal veins. PE is a serious complication which can lead to death in 30 – 60% of cases, and is more common in case of proximal DVT.
<section begin="radiology" />'''Deep vein thrombosis''' (DVT) is a form of [[venous thromboembolism]] which occurs in deep veins, most commonly in the legs or groin. Its main importance is the risk of the deep venous thrombosis dislodging and traveling to the lungs, causing [[pulmonary embolism]] (PE). DVT mostly affects the distal deep veins, but may affect the larger, proximal veins as well, including the iliac, femoral, or popliteal veins. PE is a serious complication which can lead to death in 30 – 60% of cases, and is more common in case of proximal DVT.<section end="radiology" />


== Etiology ==
== Etiology ==
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== Diagnosis and evaluation ==
== Diagnosis and evaluation ==
=== Wells score for DVT ===
When DVT is suspected, we calculate the [[pre-test probability]] of DVT to determine how to proceed. The pre-test probability of DVT can be calculated with the Wells score:
When DVT is suspected, we calculate the [[pre-test probability]] of DVT to determine how to proceed. The pre-test probability of DVT can be calculated with the Wells score:
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*** Ultrasound positive: diagnostic of DVT
*** Ultrasound positive: diagnostic of DVT


=== D-dimer ===
[[D-dimer]] is a fibrin degradation product. Its level in the blood correlates with the activity of coagulation and fibrinolysis. It’s highly sensitive for VTE and DIC, in which case the level is increased., D-dimer is not specific. It can be elevated due to other conditions, like pregnancy, cancer, infection, kidney disease, surgery, etc. Thus, D-dimer is used to rule out VTE (if the pre-test probability is low), rather than diagnose it. If D-dimer is normal, VTE is effectively ruled out (high negative predictive value). It should not be measured in those with conditions known to cause positive D-dimer.
[[D-dimer]] is a fibrin degradation product. Its level in the blood correlates with the activity of coagulation and fibrinolysis. It’s highly sensitive for VTE and DIC, in which case the level is increased., D-dimer is not specific. It can be elevated due to other conditions, like pregnancy, cancer, infection, kidney disease, surgery, etc. Thus, D-dimer is used to rule out VTE (if the pre-test probability is low), rather than diagnose it. If D-dimer is normal, VTE is effectively ruled out (high negative predictive value). It should not be measured in those with conditions known to cause positive D-dimer.
 
<section begin="radiology" />
=== Imaging ===
[[Ultrasound]] is important in the evaluation of DVT. It may show the thrombus as a hyperechoic mass in the venous lumen. When applying pressure to the vein with the ultrasound probe, an obstructed vein will not be compressible. Doppler imaging may show absent blood flow. If these findings are present, the diagnosis of DVT is made.
[[Ultrasound]] is important in the evaluation of DVT. It may show the thrombus as a hyperechoic mass in the venous lumen. When applying pressure to the vein with the ultrasound probe, an obstructed vein will not be compressible. Doppler imaging may show absent blood flow. If these findings are present, the diagnosis of DVT is made.


If D-dimer and ultrasound are inconclusive, venography with [[CT]] or [[MRI]] may be used.
If D-dimer and ultrasound are inconclusive, [[venography]] with [[CT]] or [[MRI]] may be used.
 
<section end="radiology" />
=== Screening for etiology ===
Patients with VTE without clear risk factors, especially if recurrent, should be considered for screening for a hypercoagulable state ([[thrombophilia]]) and malignancy.
Patients with VTE without clear risk factors, especially if recurrent, should be considered for screening for a hypercoagulable state ([[thrombophilia]]) and malignancy.