The treatment of choice for acute venous thromboembolism is anticoagulant 
therapy with fast-acting drugs (unfractionated or low-molecular-weight heparin 
or fondaparinux) aimed at preventing thrombus extension, followed by extended 
prophylaxis with vitamin K antagonists aimed at preventing recurrence. 
Experience accumulated over the years has demonstrated that strict laboratory 
monitoring is required for unfractionated heparin and vitamin K antagonists, 
making use of these drugs problematic for patients and physicians and prompting 
researchers to develop new anticoagulants equally effective but without the 
requirement for laboratory monitoring. The results of clinical trials to date, 
albeit limited, suggest that these new drugs will probably keep their promise. 
However, the definitive answer will come subsequent to these clinical trials, 
when clinicians will start to use these drugs to treat patients in the real 
world. It is likely that some sort of laboratory monitoring will be required at 
least for selected categories of patients. Accordingly, clinical laboratories 
should still be prepared to monitor patients, although the numbers may hopefully 
decrease sharply in the next decade or so.