Hematologists managing venous thrombosis in unusual sites face a variety of challenges, as thrombosis in these locations may have unique and obscure provoking factors. In a review article published in the European Journal of Haematology, Joseph J Shatzel, MD, of the Oregon Health and Science University in Portland, Oregon, and colleagues outlined the most recent literature regarding thrombosis of cerebral, retinal, upper extremity, hepatic, portal, splenic, mesenteric, and renal veins. The authors summarized the incidence, pathophysiology, provoking factors, and recommended treatments for each type of unusual thrombosis.

“The [clinical] evidence is poor,” Dr Shatzel told Hematology Advisor. “The role of the clinician is to take the best data they have and make the smartest management plan they can.” He noted that these types of thrombosis require clinicians to develop an individualized workup and treatment plan for each patient.

General Guidelines for Management

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For patients with idiopathic hepatic vein and splanchnic vein thrombosis, the authors recommended conducting workups for myeloproliferative neoplasm, antiphospholipid syndrome, and paroxysmal nocturnal hemoglobinuria. For patients with renal vein thrombosis, the authors suggested evaluation for nephrotic syndrome and malignancy.

The authors also suggested initiating anticoagulation in all patients with thrombosis in unusual venous sites, with the exception of retinal vein thrombosis and asymptomatic, incidentally found splanchnic vein thrombosis. Anticoagulation therapy should be given to patients for 3 to 6 months but could be given indefinitely, and the importance of tailoring the duration of treatment to the site of thrombosis was emphasized.

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The review noted a lack of scientific evidence in adequately determining the risks and benefits of anticoagulation in splanchnic vein thrombosis and prophylactic anticoagulation in nephrotic syndrome. “We need more research and we need more guidelines,” said Dr Shatzel.

Managing Retinal Vein Occlusion

Retinal vein occlusion (RVO) is a sight-threatening illness which often presents with acute, painless, unilateral vision loss. Occlusion of a branch retinal vein can be asymptomatic, or it can present with double vision or hemianopsia. RVO differs from traditional venous thrombosis in that its risk factors are similar to those of small vessel arterial disease. Current evidence suggests that hypertension, diabetes mellitus, smoking, and obesity may increase the risk of RVO. Conversely, increased physical activity, alcohol use, and increased HDL cholesterol levels may be protective.