Surgical Thromboembolism Prevention App and More from Down Under

We continue to see more and more patients diagnosed with conditions that require anticoagulation, including non-valvular atrial fibrillation, new or recurrent venous thromboembolism, mechanical heart valves, and arterial thrombosis. Frequently, these patients require surgery or other procedures during which the anticoagulation must be stopped or rapidly reversed. In the age of both warfarin and the new target-specific oral anticoagulants (TSOACs) this has become an increasingly complicated process. When to stop then restart a patient’s apixaban before an elective surgery? What about emergency surgery? How do you prevent thromboembolism in patients not on anticoagulation?

With so many potential patient care scenarios that require thromboembolism prevention and/or anticoagulation and numerous treatment choices, where can a provider turn for a good point of care resource? Previously here at iMedicalApps, we have highly recommended the outstanding American College of Cardiology’s Anticoag Evaluator for non-valvular atrial fibrillation or the excellent MAQI2 Anticoagulation Toolkit from the University of Michigan. We also recommend the CDC’s Anticoagulation Manager since it also covers anticoagulation recommendations for VTE, fetal loss, HIT, and arterial thrombosis in addition to atrial fibrillation. None of these apps include detailed information on surgical thromboembolism prevention. This is where the new app, CLOTS, from the Peter MacCadllum Cancer Center in Australia comes to the rescue.

Although the app is based in non-U.S. international/metric system units, it can still easily assist the busy provider in deciding what method of surgical thromboembolism prevention a given patient requires as well as how to manage anticoagulants pre- and post-op.

Evidence-based medicine

Developed by the Peter MacCallum Cancer Center in Victoria, Australia, CLOTS provides easy-to-follow algorithms to calculate surgical thromboembolism prevention, anticoagulant management pre- and post-op, warfarin reversal, and blood volume optimization data to iOS. The app is more surgical focus than the CDC or ACC coagulation apps. Although the app does not cite specific evidence-based guidelines or articles, it appears to provide information consistent with current U.S. guidelines.

Who would benefit from this app?

Nurses, students, pharmacists, residents, mid-levels, primary care providers, emergency medicine, internal medicine and hospitalist providers, surgeons, CRNAs/anesthesiologists or any provider who prescribes/manages patients on anticoagulation.

Disclaimer: The views expressed are those of the author(s) and do not reflect the official policy of the Department of the Army, the Department of Defense or the U.S. Government.

  • Price
    • Free
    • Comprehensive scenario-based information on surgical thromboembolism prevention
    • Uses easy-to-follow algorithms/calculators for recommendations
    • Covers gamut from NOACs to warfarin to transfusions
  • Dislikes
    • No references included
    • Calculators assume international/metric units
    • Not available for Android
  • Overall

    The CLOTS app comes from “Down Under” in Australia from a renown cancer hospital and enables users to quickly determine when to start, hold, stop, and restart anticoagulants around surgical procedures. The app is easy to use and seems to provide the same recs as does the ACC/CDC apps. Would appreciate seeing more references/hyperlinks to pertinent materials.


  • Overall Score
  • User Interface

    Easy-to-follow interface but cannot change to U.S. units.

  • Multimedia Usage

    Minimal multimedia information, but links to app website, ability to share app, etc.

  • Price


  • Real World Applicability

    The CLOTS app could be essential for those taking care of patients on anticoagulants awaiting surgery. The app gives specific, easy-to-calculate recs for stopping and restarting anticoagulants, warfarin reversal, etc. Although not the only app to make these calculations, it is one of the easiest to use (with some minor metric system changes).

  • Device Used For Review

    iPhone 8 running iOS 12.1

  • Available for DownloadiPhoneiPad