the causes for this condition are the following: * Obstruction by deep vein thrombosis or tumors (most commonly renal cell carcinoma) * Compression through external pressure by neighbouring structures or tumors, either by significantly compressing the vein or by promoting thrombosis by causing turbulence by disturbing the blood flow. This is quite common during the third trimester of pregnancy when the uterus compresses the vein in the right side position. * Iatrogenic causes may be suspected in patients with a medical history of liver transplantion, vascular catheters, dialysis and other invasive procedures in the vicinity * Budd-Chiari syndrome
Inferior vena cava syndrome
Superior vena cava syndrome
Mediastinitis
Aortocaval compression syndrome
Subclavian steal syndrome
Pulmonary hematoma
COACH syndrome
Fat embolism syndrome