Radiology In Plain English radiology reports explained

Can CT detect a Deep Vein Thrombosis (DVT)?

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A deep vein thrombus is a clot that develops in a deep vein.  This can be in the arms, legs, or pelvis.  A deep vein thrombus can be a deadly condition because these clots can travel to your lungs.  This is called a pulmonary embolism.  A pulmonary embolism can be deadly in some cases.

A deep  vein thrombosis has many risk factors such as injury, chronic illness like cancer, immobility, obesity amongst many others.  A DVT is most common in the leg and can sometimes have symptoms like leg pain, swelling and redness of the skin.  A DVT is most often diagnosed with an ultrasound.

A DVT can also be found on CTs done for unrelated reasons.  A DVT can be without symptoms.  When radiologists look at CTs, we look at all the structures including the deep veins regardless of the patient’s history or complaints.  Every so often I will diagnose a DVT in patients who have unrelated problems.  This is especially common in patients who have chronic illness like cancer.

A Deep vein thrombosis will be a filling defect.  This is a dark spot in a blood vessel that is ordinarily completely highlighted by contrast injected through a vein.  Unfortunately, a dark spot in a blood vessel can also represent a mixing artifact.  That is, blood mixing with the contrast administered through a vein.   Usually, this has a more ill defined fuzzy appearance but can be hard to tell sometimes.  In DVT, the vein will also be larger than the other side.

In the case of an abdominal pelvic CT, I will look up into the visible lungs to make sure there is no pulmonary embolism.  I will call the referring doctor to let them know about the clot since it needs to be treated as soon as possible.

I will often recommend an ultrasound to confirm the diagnosis since this is the preferred test.  Sometimes a CT of the chest will be ordered to look for clots which have gone to the lungs.  This is most common when the patient has symptoms like chest pain.

A deep vein thrombosis diagnosis can be raised on CT in some cases.     Since the contrast is mixing with blood in vessels, this can be tricky sometimes and over called.  Since blood clots can be without symptoms, it would be reasonable to get an ultrasound to make sure there is no clot since this is the preferred test.

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About the author

A. Mendelson, MD
Radiology In Plain English radiology reports explained