Low-Molecular-Weight Heparin and Venous Thrombosis

Excerpt

To the Editors: The study by Green and colleagues (1) compared unfractionated with low-molecular-weight heparins in preventing thrombotic complications in patients with recent spinal cord injury and paralysis. The investigators suggest that low-molecular-weight heparin is superior to unfractionated heparin.

In the trial, however, the three noninvasive methods dramatically failed to detect venous thrombosis accurately or reliably. First, more than half (four of seven) of the positive flow studies were falsely so, as determined by subsequent negative contrast venograms. Second, no thrombosis below the popliteal vein was noted. This finding is surprising in view of the occurrence of proximal clots, but