Aspirin for Post-Operative VTE Prophylaxis

Evidence-Based Recommendations by Surgical Context

The American College of Chest Physicians (ACCP) explicitly advises against using aspirin as the sole method of thromboprophylaxis in non-orthopedic surgical patients (Grade A recommendation) 4, 1, 2, 3
Aspirin should only be considered in non-orthopedic surgery when LDUH and LMWH are contraindicated or unavailable—it is not a first-line option 1, 2, 3
Low-dose aspirin (160 mg daily) reduces symptomatic DVT by 28% (RR 0.72, 95% CI 0.53-0.96) and fatal PE by 58% (RR 0.42, 95% CI 0.25-0.72) compared to placebo in orthopedic patients 1, 2, 3
The American College of Chest Physicians recommends thromboprophylaxis with aspirin only when concomitant risk factors are present (Grade A-B recommendation) in knee arthroscopy patients 4
Simple knee arthroscopy has low thrombotic risk (9% asymptomatic DVT, 3% proximal DVT), so routine prophylaxis is not indicated 4
Aspirin prophylaxis may be considered following vascular surgery, particularly for arterial thrombosis prevention 5
For PTA/PTAS procedures: aspirin 325 mg daily should be continued indefinitely post-procedure (combined with clopidogrel for first 4 weeks) 6

Patients with elevated PE risk: Aspirin is not recommended when there is specifically high risk for pulmonary embolism 4
Active bleeding: Aspirin must be withheld until bleeding is controlled 5
High VTE risk with high bleeding risk: Use mechanical prophylaxis (IPC) instead of any pharmacologic agent 8
Patients already on dual antiplatelet therapy (DAPT): Adding anticoagulation to DAPT significantly increases bleeding risk; use mechanical prophylaxis instead 8
LMWH and other anticoagulants are more effective than aspirin for preventing asymptomatic DVT detected by venography 4, 1

Aspirin should be withheld until bleeding is controlled in ET patients with elevated platelet counts 5
Prophylaxis with aspirin may be considered following vascular surgery in patients with myeloproliferative neoplasms 5
Guidelines specifically recommend against using aspirin for VTE prevention in critically ill COVID-19 patients 10
Post-discharge aspirin can be considered as an alternative to LMWH/DOACs for low-risk patients after orthopedic-type procedures 10
For isolated lower extremity injuries with/without immobilization, ACCP advises against routine prophylaxis (Grade 1A) 4
If risk factors present, LMWH preferred over aspirin in lower extremity injuries 4