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Content Update

September 26, 2023

New data evaluating the role of aspirin for the prevention of venous thromboembolism: Since the 2012 CHEST guidelines on venous thromboembolism (VTE) prevention, there have been additional randomized controlled trials (RCTs) evaluating the role of aspirin in prevention of VTE in orthopedic and fracture procedures. This potentially adds an inexpensive, widely available, and oral option for select patients. The EPCAT II trial studied a direct oral anticoagulant (DOAC) plus aspirin regimen in patients undergoing total hip or total knee replacement surgeries and demonstrated noninferiority to extended aspirin therapy after an initial acute DOAC treatment. More recently, the PREVENT CLOT study compared aspirin 81 mg BID to low molecular weight heparin (LMWH) in adults with a fracture and found aspirin to be noninferior to LMWH in preventing death.



Upon completion of the chapter, the reader will be able to:

  1. Identify risk factors and signs and symptoms of deep vein thrombosis (DVT) and pulmonary embolism (PE).

  2. Describe the processes of hemostasis and thrombosis.

  3. Determine a patient’s risk of developing venous thrombosis.

  4. Formulate an appropriate prevention strategy for a patient at risk for DVT.

  5. Select and interpret laboratory test(s) to monitor antithrombotic medications for safety and efficacy.

  6. Identify factors that place a patient at high risk of bleeding while receiving antithrombotic medications.

  7. State at least two potential advantages of newer anticoagulants (ie, low-molecular-weight heparins [LMWHs], fondaparinux, oral direct thrombin inhibitors [DTIs], and oral direct factor Xa inhibitors) over traditional anticoagulants (ie, unfractionated heparin and warfarin).

  8. Manage a patient with toxicity secondary to an anticoagulant with or without bleeding.

  9. Identify relevant factors such as drug–drug and drug–food interactions to optimize anticoagulant medication selection.

  10. Formulate an appropriate treatment plan, including duration and monitoring, for a patient who develops a DVT or PE.


Venous thromboembolism (VTE) is one of the most common cardiovascular disorders in the United States. VTE is manifested as deep vein thrombosis (DVT; ie, thrombus causing obstruction of a deep vein in the leg, pelvis, or abdomen) and pulmonary embolism (PE; ie, thrombus causing obstruction of a pulmonary artery or one of its branches and resulting in pulmonary infarction) (Figure 11–1).1,2 A thrombus is a blood clot attached to the vessel wall composed of platelets, fibrin, and clotting factors that may partially or completely occlude the lumen of a blood vessel and compromise blood flow and oxygen delivery to distal tissue. It is often provoked by prolonged immobility or vascular injury and most frequently seen in patients hospitalized for a serious medical illness, trauma, or major surgery. VTE can also occur with little or no provocation in patients who have an underlying hypercoagulable disorder.

FIGURE 11–1.

Venous circulation. (From Witt DM, Clark NP, Vazquez SR. Venous thromboembolism. In: DiPiro ...

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