Unfractionated heparin (UH), administered subcutaneously in low doses of 5000 U every 12 h, is safe and effective in preventing
thrombosis in most patients. However, in persons with neurological disease, surgical replacement of joints, or operations for
cancer, low-dose UH is often inadequate or unsafe, and dose-adjusted UH,
warfarin, or low molecular weight heparins (
LMWH) may be needed. In
trauma patients,
LMWH is significantly more effective than UH in reducing the frequency of DVT with a minimal increase in
bleeding risk.
LMWH also significantly decreases
thromboembolism in patients with acute
spinal cord injury and complete motor
paralysis, and with less
bleeding as compared to UH. In
acute stroke, a
heparinoid was more effective than either placebo or UH (5000 U every 12 h) in preventing
deep-vein thrombosis in
acute thrombotic stroke, and the risk of
bleeding was low. Following total hip or knee replacement,
LMWH is more efficacious than
warfarin but may be associated with perioperative
bleeding. The duration of thrombo-prophylaxis following
arthroplasty is controversial; venography demonstrates thrombi in approximately 29% of patients after hospital discharge, but only 3% have clinical symptoms. Lastly, perioperative
thrombosis in
cancer patients having abdominal surgery has been decreased by
LMWH, and experience with outpatient treatment in the long-term management of Trousseau's syndrome has been positive.