Zwicker ZI et al. - Tumor cells are known to shed TF-bearing microparticles in vitro, and circulating TF-bearing microparticles can be measured in plasma samples from patients with advanced cancer. The authors currently use an impedance-based flow cytometer to accurately size and enumerate TF-bearing microparticles to explore the association between cancer thrombosis and elevations in circulating TF-bearing microparticles.