Compression of left common iliac vein is independently associated with left-sided deep vein thrombosis

ObjectiveLeft-sided lower extremity deep vein thrombosis (DVT) is more common than right-sided DVT. This difference was found to be caused by the compression of the left iliac common vein (LCIV). To evaluate and compare LCIV compression in unilateral DVT patients and the normal population and investigate the association of LCIV compression with the risk of left-sided DVT.MethodsA retrospective analysis of records and computed tomography imaging was conducted in 19 right DVT, 60 left DVT, and 218 control subjects. The influences of LCIV diameter and stenosis on the risk of left DVT were investigated using logistic regression analysis.ResultsIn control subjects, 51.8% had greater than 50% compression of the LCIV, and 24.3% had greater than 70% compression. Mean LCIV diameter was smaller in left DVT (2.39 mm) than in right DVT (6.18 mm) or normal control (5.39 mm). Mean LCIV stenosis was higher in left DVT (77.57%) than in right DVT (38.01%) or normal control (49.31%). The odds of left DVT increased by a factor of 2.69 for each millimeter decrease in LCIV diameter and 2.78 for each 10% increase in LCIV stenosis. With LCIV stenosis >75%, the risk of left DVT was associated with an 11-fold increase, and with LCIV diameter <2.5 mm, the risk was associated with a 13.5-fold increase. Unprovoked and provoked left DVT patients had similar LCIV compression, and left DVT patients had more significant LCIV compression than right DVT patients.ConclusionsLCIV compression was a normal anatomical pattern with an increased risk of left DVT. LCIV compression might be the essential and prereqisite factor for left DVT. Patients with severe LCIV compression should receive more emphasis on left DVT prophylaxis because they are the high-risk population of left DVT.