Thrombo-embolic Phenomenon

CASE: 65 yo lady, has colon ca, admitted today, scheduled to have surgery in 3 days. What’s her risk for DVT?

  • High, why? multiple risk factors: age, gender, cancer, hospitalisation, immobility
  • Use caprini risk assessment tool to objectively asses the risk of DVT


How to prevent DVT?

  • Early mobilization: going to the bathroom, walking in the hallway
  • Mechanical prophylaxis:
    • Elastic stockings are not that effective -> associated w\ skin abrasion
    • Intermittent pneumatic compression devices
  • Anticoagulants: heparin;
    • LMWH: smaller, selected molecules with homogenous size -> predictable absorption
    • Unfractionated: heterogenous, different sizes -> absorption is unpredictable
    • Aspirin is not used for DVT prophylaxis


  • Advantages of LMWH over unfractionated -> used once per day, less risk of heparin-induced thrombocytopenia (HIT)
  • For DVT prophylaxis, both types of heparin are given SQ:
    • LMWH -> 40 mg daily
    • Unfractionated -> 5000 units TID


  • Start DVT prophylaxis at admission
  • Hold DVT prophylaxis 12 hrs pre-op
  • Resume DVT prophylaxis 8 hrs post-op (homeostasis occurs 6-8 hours after cutting)
  • Continue for the duration of hospitalization for most pts
  • Extend if cancer + orthopaedic (hip\knee replacement) surgery patients -> 4 weeks (up to 35 days)


  • Before giving anticoagulants -> asses the risk of bleeding; active bleeding, gastric ulcer, intracranial haemorrhage, INR (>1.5 is a risk), APTT, ptt count (<50,000 is a risk)
  • If high risk of bleeding -> use mechanical prophylaxis (intermittent pneumatic compression)
  • IVC filter:
    • Lowers the risk of PE, but has a higher risk of DVT
    • Indications: prev recent PE where you can’t use anticoagulants during procedure -> use it temporarily to cover that period


CASE: 3 days post-op, pt comes w\ SOB and hypoxia. What to do?

  • H&P, may include Wells score for PE
  • D-dimer is not recommended (has high negative predictive value in low clinical suspicion pts)
  • Do spiral CT
  • If high clinical suspicion, we can give heparin until we get the result of CT (w\ low risk of bleeding)
  • Treatment dose of heparin for PE?
    • Enoxaparin: 1 mg\kg\12 hrs
    • Unfractionated: using protocol -> 80 units bolus, followed by 18 units/kg/hr


  • Very imp to reach anticoagulation as soon as possible -> failure -> recurrence
    • This is why using Enoxaparin is preferred -> the dose of 1 mg\kg\12 hrs is predictable and therapeutic
    • But using unfractionated heparin -> we need to use a protocol to reach therapeutic aptt; otherwise, it might take some time


Other cardioembolic events in surgical pts:

  • Stroke (risk is A fib -> 6% per yr)
  • Acute limb ischemia
  • Mesenteric ischemia


Side note:

  • Pt is taking aspirin -> hold it 7 days pre-op (depends on procedure, if small -> no need to stop it)
  • Pt is taking Plavix -> hold it 5 days pre-op (higher risk of bleeding)


Caprini score:

Thromboebolic 1

Thromboebolic 2



Download the PDF version: here


  • Dr Aldorzi’s lecture

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