Introduction
Deep vein thrombosis, or DVT, is one of the main manifestations of venous thromboembolism and consists of thrombus formation within the deep venous system, usually in the lower limbs. Early recognition is essential, not only because of the risk of local progression, but above all because of the possibility of pulmonary embolism, a potentially fatal complication.
Assessment of clinical probability
The first step is to assess clinical probability using the Wells score for DVT. This tool stratifies patients into low, intermediate or high probability categories and guides the need for further testing. In patients with low or intermediate probability, D-dimer testing plays an important role. A negative result allows DVT to be safely excluded in most cases.
Role of D-dimer and venous ultrasound
When D-dimer levels are elevated, compression venous ultrasound should be performed. In patients with a high clinical probability, or whenever there is a strong suspicion of DVT, venous Doppler ultrasound should be performed directly, without prior D-dimer testing. This is the first-line examination for diagnostic confirmation, particularly in proximal thrombosis.
Distal and proximal DVT
Once the diagnosis has been confirmed, it is important to distinguish between distal and proximal DVT. Proximal thromboses involving the popliteal, femoral or iliac veins carry a higher risk of pulmonary embolisation and warrant systematic anticoagulation. Isolated distal thromboses require additional assessment of the risk of progression.
Risk of progression in distal DVT
In isolated distal DVT, factors such as severe symptoms, extensive thrombosis, proximity to the proximal veins, absence of a transient provoking factor, previous venous thromboembolism, active cancer or hospital admission increase the risk of thrombus extension. When these factors are present, anticoagulation is generally indicated. In their absence, serial ultrasound surveillance may be considered.
Anticoagulation
Once the need for treatment has been established, direct oral anticoagulants are currently the preferred option for most patients. Medicines such as apixaban, rivaroxaban, edoxaban and dabigatran have proven efficacy and are more convenient to use. However, alternative strategies should be considered in certain situations, including pregnancy, high-risk antiphospholipid syndrome, advanced renal impairment and selected cancer-associated settings.
Treatment duration
After anticoagulation is started, one of the most important decisions concerns treatment duration. The recommended minimum duration is 3 months. The decision to stop or extend treatment should be based on the balance between the risk of recurrent venous thromboembolism and the risk of bleeding.
Factors favouring discontinuation or extended treatment
When DVT is associated with a major transient risk factor, such as recent surgery, significant trauma or temporary immobilisation, 3 months of anticoagulation is generally sufficient. In contrast, when thrombosis occurs without an identifiable provoking factor, or in the presence of persistent factors such as active cancer, high-risk thrombophilia or previous venous thromboembolism, extended anticoagulation should be considered, provided that the bleeding risk is acceptable.
Bleeding risk
Periodic reassessment of bleeding risk is essential. Factors such as older age, previous major bleeding, renal or hepatic impairment, anaemia, thrombocytopenia, concomitant use of antiplatelet agents or non-steroidal anti-inflammatory drugs, and a history of frequent falls should be considered. These factors may influence the decision to continue or discontinue treatment.
Follow-up
During follow-up, general measures should be reinforced, including early mobilisation, management of cardiovascular risk factors, smoking cessation, weight reduction when indicated, and patient education regarding signs of recurrent thrombosis and bleeding complications.
Conclusion
This algorithm provides a systematic approach to DVT by integrating clinical probability, imaging confirmation, assessment of progression risk and an individualised decision on the duration of anticoagulation. The aim is to maximise prevention of recurrence and pulmonary embolism while minimising the risk of treatment-related bleeding complications.
