Iliac vein compression as risk factor for left- versus right-sided deep venous thrombosis: case-control study

Abstract

Purpose: To determine if compression of the left common iliac vein (LCIV) by the right common iliac artery is associated with left-sided deep venous thrombosis (DVT).

Materials and methods: This institutional review board-approved case-control study was performed in a cohort of 230 consecutive patients (94 men, 136 women; mean age, 57.5 years; range, 10-94 years) at one institution who had undergone contrast material-enhanced computed tomography of the pelvis prior to a diagnosis of unilateral DVT. Demographic data and information on risk factors were collected. Two board-certified radiologists determined iliac vein compression by using quantitative measures of percentage compression {[1 minus (LCIV diameter at point of maximal compression/distal right common iliac vein diameter)] times 100%}, as well as qualitative measures (none, mild, moderate, severe), with estimates of measurement variability. Logistic regression analysis was performed (independent variable, left vs right DVT; dependent variable, iliac vein compression). Cutpoints of relevant compression were evaluated by using splines. Means (with 95% confidence intervals [CIs]) and odds ratios (ORs) (and 95% CIs) of left DVT per 1% increase in percentage compression were calculated.

Results: Patients with right DVT were more likely than those with left DVT to have a history of pulmonary embolism. Overall, in all study patients, mean percentage compression was 36.6%, 66 (29.7%) of 222 had greater than 50% compression, and 16 (7.2%) had greater than 70% compression. At most levels of compression, increasing compression was not associated with left DVT (adjusted ORs, 1.00, 0.99, 1.02) but above 70%, LCIV compression may be associated with left DVT (adjusted ORs, 3.03, 0.91, 10.15).

Conclusion: Increasing levels of percentage compression were not associated with left-sided DVT up to 70%; however, greater than 70% compression may be associated with left DVT.

Supplemental material: http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.12111580/-/DC1.

Figure 1:

Patient flow diagram.

Figure 2:

Data entry form. AA = abdominal aorta.

Figure 3:

Density plots of compressed LCIV diameter according to side of DVT.

Figure 4:

Density plots of percentage LCIV compression values according to side of DVT and reference used in the denominator to define compression. Left: LCIV as the reference. Right: RCIV as the reference.

Figure 5:

Odds of left DVT versus percentage LCIV compression (using distal RCIV as reference denominator) is modeled by using logistic regression with splines (solid line with dots) with 95% confidence limits (upper and lower lines). Knots are set at 0% and 70% with reference at 36.6%. Density plot with distributions of percentage compression values by side of DVT is overlaid on top of regression lines (blue line = patients with left-sided DVT, orange line = patients with right-sided DVT). kdensity = Frequency of patients with left-sided DVT or right-sided DVT with a given level of percentage stenosis.