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Venous Thromboembolism

Superficial Vein Thrombosis: A Review

Author/s: 
Gregory Piazza, Darsiya Krishnathasan, Nada Hamade

Importance: Superficial vein thrombosis (SuVT) is characterized by thrombus in the superficial veins, typically in the lower or upper extremities, and has an estimated annual incidence of 64 to 131 per 100 000 person-years. Approximately 10% of patients with SuVT progress to deep vein thrombosis (DVT) or pulmonary embolism (PE).

Observations: Endothelial injury (caused by infection or intravenous devices), venous stasis (such as from chronic venous insufficiency or prolonged immobility), and hypercoagulability (due to cancer or pregnancy) are pathophysiologic factors associated with SuVT. Clinical risk factors for lower extremity SuVT are similar to those of DVT and PE and include pregnancy, varicose veins, and active cancer. The incidence of SuVT is greater in females than males (78-167 compared with 49-116 per 100 000 person-years). In contrast with lower extremity SuVT, upper extremity SuVT is primarily caused by indwelling intravenous catheters. Patients typically present with a tender, red, palpable cord under the skin in the upper or lower extremity. D-dimer testing has a sensitivity of approximately 48% to 74.3% and, therefore, is not reliable for excluding SuVT. Approximately 25% of patients with lower extremity SuVT present with concomitant DVT, likely because risk factors for SuVT and DVT are similar and because SuVT can extend into deep veins. In people without classic symptoms and signs of SuVT, ultrasonography can establish the presence and extent of the thrombus. Management may include elastic compression stockings and nonsteroidal anti-inflammatory drugs. For patients with SuVTs that are at least 5 cm long or those with persistent or worsening symptoms despite several days of conservative therapy, treatment includes anticoagulation with fondaparinux 2.5 mg. Alternative anticoagulation treatment includes rivaroxaban 10 mg once daily and low-molecular-weight heparins (eg, enoxaparin 40 mg once daily), which may reduce subsequent venous thromboembolic events. SuVT located within 3 cm of a deep vein should be treated with therapeutic doses of anticoagulation such as direct oral anticoagulants.

Conclusions and relevance: SuVT typically presents as a tender, painful, palpable cord under the skin. Management may include elastic compression stockings, nonsteroidal anti-inflammatory drugs, and systemic anticoagulation with fondaparinux 2.5 mg or rivaroxaban 10 mg. SuVTs within 3 cm of a deep vein should be treated with therapeutic dose anticoagulation.

Keywords 
surgery vascular surgery Venous Thromboembolism Cardiology anticoagulants

Diagnosis and Treatment of Polycythemia Vera: A Review

Author/s: 
Douglas Tremblay, Marina Kremyanskaya, John Mascarenhas, Ronald Hoffman

Importance: Polycythemia vera (PV), a myeloproliferative neoplasm characterized by an increased red blood cell mass and increased risk of thrombosis, affects approximately 65 000 people in the US, with an annual incidence of 0.5 to 4.0 cases per 100 000 persons.

Observations: Erythrocytosis (hemoglobin >16.5 mg/dL in men or >16.0 mg/dL in women) is a required diagnostic criterion, although thrombocytosis (53%) and leukocytosis (49%) are common. Patients may have pruritus (33%), erythromelalgia (5.3%), transient visual changes (14%), and splenomegaly (36%) with abdominal discomfort. More than 95% of patients have a JAK2 gene variant, which helps distinguish PV from secondary causes of erythrocytosis, such as tobacco smoking or sleep apnea. Among 7 cohorts (1545 individuals), the median survival from diagnosis was 14.1 to 27.6 years. Prior to or at the time of PV diagnosis, arterial thrombosis occurred in 16% of patients and 7% had venous thrombotic events, which could involve unusual sites, such as splanchnic veins. PV is also associated with an increased bleeding risk, especially in patients with acquired von Willebrand disease, which can occur with extreme thrombocytosis (platelet count, ≥1000 × 109/L). All patients with PV should receive therapeutic phlebotomy (goal hematocrit, <45%) and low-dose aspirin (if no contraindications). Patients who are at higher risk of thrombosis include those aged 60 years or older or with a prior thrombosis. These patients and those with persistent PV symptoms may benefit from cytoreductive therapy with hydroxyurea or interferon to lower thrombosis risk and decrease symptoms. Ruxolitinib is a Janus kinase inhibitor that can alleviate pruritus and decrease splenomegaly in patients who are intolerant of or resistant to hydroxyurea. About 12.7% of patients with PV develop myelofibrosis and 6.8% develop acute myeloid leukemia.

Conclusions and Relevance: PV is a myeloproliferative neoplasm characterized by erythrocytosis and is almost universally associated with a JAK2 gene variant. PV is associated with an increased risk of arterial and venous thrombosis, hemorrhage, myelofibrosis, and acute myeloid leukemia. To decrease the risk of thrombosis, all patients with PV should be treated with aspirin and therapeutic phlebotomy to maintain a hematocrit of less than 45%. Cytoreductive therapies, such as hydroxyurea or interferon, are recommended for patients at high risk of thrombosis.

Keywords 
Polycythemia Vera Hematologic Cancer oncology Hematology Venous Thromboembolism Leukemias
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