Prevention of Venous Thromboembolism (VTE)

Created 22/02/2022, last revision 04/11/2023

  • deep vein thrombosis (DVT) is a condition characterized by the formation of blood clots in veins. It most commonly occurs in the deep veins of the calf or thigh but can also appear in other parts of the body (such as the deep pelvic veins, veins in the abdomen, or arms)
  • immobility increases the risk of DVT
  • without prevention, DVT is detected in the first two weeks in up to 50% of immobile patients  [Brandstater, 1992]
    • thrombi form in the paretic leg and/or the pelvic veins
    • approx. 2/3 of thrombi occur below the knee and are often asymptomatic, though there is a risk of proximal thrombus extension
    • most symptomatic DVTs are located proximally (thigh, pelvis)
    • most DVTs occur between days 3-7
  • the most feared complication is pulmonary embolism (PE)  Pulmonary embolism on CTA
  • in bedridden patients, regular calf examinations are advisable (for swelling and palpation pain); nonetheless, many thromboses remain asymptomatic
  • recommended VTE prophylaxis:

Mechanical prophylaxis

  • early physical therapy and verticalization
  • intermittent pneumatic compression – IPC (e.g., Venaflow, Kendall, etc.) (AHA/ASA 2019 I/B-R)
    • the effect of IPC and LMWH is comparable  [Wan, 2015]
    • the CLOTS 3  trial showed a reduction in 30-day mortality (13.1⇒10.8%) and incidence of DVT (12.1%⇒8.5%); in this study, a proportion of patients in both arms had LMWHs as well
    • IPC should be interrupted for as short time as possible (skin hygiene, physical therapy) ⇒ IPC is designed for continuous use (CLOTS 3)
  • do not use elastic compression stockings
Intermittent pneumatic compresion (Venaflow) used in prevention of venous thromboembolism (VTE)


  • in general, the benefit of prophylactic administration of subcutaneous heparin (UFH or LMWH) in patients with acute stroke is not well established (AHA/ASA 2019 IIb/A)
    • there were no significant effects on death or disability for LMWH compared with UFH
    • LMWH was associated with a statistically significant reduction in mostly asymptomatic DVTs
  • in routine practice, medical prophylaxis is used; according to data from the PREVAIL trial, enoxaparin 40 mg 1xd may be preferred to heparin 2x 5000 IU given its better clinical benefits-to-risk ratio and convenience of once-daily administration [Sherman, 2007]


According to the AHA/ASA guidelines 2019, IPC is the preferred prophylactic method.
The most effective approach is a combination of LMWH and IPC (Wan, 2015)

How to proceed in different types of stroke

Ischemic stroke

  • the most effective is a combination of IPC + LMWH. In thrombolysed patients, postpone LMWHs for 24 hours
  • LMWH administration at doses higher than prophylactic is not recommended due to an increased incidence of hemorrhagic complications)
Subarachnoid hemorrhage

  • IPC should be initiated on the day of diagnosis
  • LMWH only after securing the aneurysm
Intracerebral hemorrhage  (AHA/ASA guidelines 2022)

  • IPC should be initiated on the first day (AHA/ASA guidelines 2022 1/B)
  • LMWH can be initiated between 24-72 hours from ICH onset if bleeding is stable (confirmed by stationary brain CT), coagulation is normal, and blood pressure is compensated  (AHA/ASA 2022 2b/C)
  • graduated compression stockings, whether knee-high or thigh-high, are not beneficial for VTE prophylaxis (AHA/ASA 2022 3/B

Consider implantation of Inferior Vena Cava (IVC) filter in SAH or ICH patients with acute PE or DVT (AHA/ASA 2010 class IIb, LoE C)

Inferior vena cava filter
Inferior vena cava filter

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Prevention of Venous Thromboembolism (VTE) in stroke patients