Venous Thrombosis - The Current Status
There is strong evidence to define the incidence of venous thromboembolism (VTE) in high-risk situations, underlying haematological factors that increase the risk, short- and long-term sequelae and optimal management. VTE is particularly frequent following abdominal and lower limb orthopaedic surgery. The duration for increased risk, for example after joint replacement operations, is now known to be prolonged for some 4-6 weeks. There is also convincing evidence to relate VTE to many medical disorders and to travellers' thrombosis. Underlying coagulation abnormalities that increase the risk are endogenous due to thrombophilia, and exogenous from intercurrent illness, blood dyscrasias, oral contraception or hormone-replacement therapy. Spontaneous VTE is usually due to one or more of these predisposing factors. Prophylaxis regimes have been developed for subjects at increased risk, varying from simple lower limb compression through regimes with low molecular weight heparin, oral warfarin or newer agents. Trials show reduced incidence of deep vein thrombosis or non-fatal pulmonary embolism but no reduction for fatal pulmonary embolism, undoubtedly reflecting the need for larger patient numbers. If VTE is detected, therapeutic regimes are proven to minimise risk of serious early or late sequelae - a major advance has been to safely manage most patients out of hospital. The problem in practice is to strictly implement prophylactic and therapeutic regimes in all patients. Acute clinical deep vein thrombosis is best detected or excluded by the duplex ultrasound scan. A negative D-dimer test can define most patients who do not have deep vein thrombosis but is realistically only an excuse to avoid performing ultrasound scans out of hours. Prophylactic ultrasound screening may be cost-effective in high-risk patients as so many have silent VTE that could present with fatal pulmonary embolism or late post-phlebitic syndrome.