Traditionally, patients with acute deep vein thrombosis (DVT) are treated with strict bed rest for several days to avoid clots from breaking off and causing pulmonary emboli. The purpose of this study is to give a precise estimate of short term complications like pulmonary embolism, bleeding, heparin-induced thrombocytopenia (HIT) and death in a cohort of consecutive patients who were admitted because of acute symptomatic DVT, all treated by compression and walking exercises instead of conventional bed-rest and nearly all by low-molecular-weight heparin.

In 1289 consecutive patients the following five endpoints were registered for the period of hospital-stay: 1. Frequency of pulmonary embolism (PE) at admission (V/Q lung scan), 2. Frequency of new PE's after 10 days (second lung scan), 3. Fatal events (autopsy), 4. Frequency of malignant disease, 5. Bleeding complications and HIT.

1. 190/356 (53.4% of iliofemoral, 355/675 (52.6%) of femoral and 84/239 (35.1%) of lower leg vein thrombosis showed PE (difference iliofemoral and femoral versus lower leg DVT p < 0.001). Two thirds of these PE were asymptomatic. 2. New PE after 10 days in comparison to the baseline scan occurred in 7.4%, 6.4% and 3.4% respectively. 3. Fatal events, all investigated by autopsy, were caused by PE in 3 patients aged over 76 years (0.23%), by malignant diseases in 12 (0.9%) and due to other causes in 2 (0.15%). 4. 232 patients (18%) had associated malignant diseases, from which 33% were detected by our screening. 5. Non-fatal bleeding complications were seen in 3.3%, including 5 patients (0.4%) with major bleeding. Three patients (0.2%) suffered from HIT II.

The low incidence of recurrent and fatal pulmonary emboli in this series affirms the value of early ambulation with heavy leg compression in patients with symptomatic acute leg deep venous thrombosis. In addition, the presence of pulmonary emboli in one-third of those with calf vein thrombi emphasizes the importance of fully diagnosing and treating calf clots.