From the Guidelines

Aspirin can be used for Deep Vein Thrombosis (DVT) prophylaxis, but it is not a recommended alternative to anticoagulation.

Aspirin is less effective at preventing recurrent VTE than anticoagulants, with 53 fewer events per 1,000 cases (from 84 fewer to 13 fewer) compared to no aspirin 1
The use of aspirin for DVT prophylaxis is suggested in patients who are stopping anticoagulant therapy and do not have a contraindication to aspirin, with a weak recommendation and low-certainty evidence 1
Aspirin's benefits must be balanced against its risk of bleeding and inconvenience, with 3 more events per 1,000 cases (from 6 fewer to 28 more) of major bleeding compared to no aspirin 1
The net benefit of extended anticoagulant therapy in patients with unprovoked VTE is substantially greater than the benefits of extended aspirin therapy 1

Aspirin may be considered in patients who have decided to stop anticoagulants, but its use should be reevaluated due to the potential risk of bleeding and inconvenience
The decision to use aspirin for DVT prophylaxis should be made on a case-by-case basis, taking into account the individual patient's risk factors and medical history
Anticoagulants are generally preferred over aspirin for DVT prophylaxis due to their greater efficacy in preventing recurrent VTE 1

From the FDA Drug Label

Aspirin can be used for Deep Vein Thrombosis (DVT) prophylaxis as it has anticoagulant properties, which may help prevent blood clots 2.

The drug label warns about stomach bleeding, which is a common risk associated with anticoagulant use.
It also advises against taking aspirin with other NSAIDs or anticoagulants, which could increase the risk of bleeding.
However, the label does not provide specific guidance on using aspirin for DVT prophylaxis, and it is essential to consult a doctor before using aspirin for this purpose, especially for patients with a history of stomach problems, high blood pressure, heart disease, liver cirrhosis, or kidney disease 2.

Aspirin has been studied as a potential prophylactic agent for deep vein thrombosis (DVT) in various patient populations, including those undergoing orthopedic surgery and trauma patients 3, 4, 5.
The evidence suggests that aspirin may be effective in preventing DVT, particularly in patients who have had a previous episode of venous thromboembolism (VTE) 3, 5.
A study published in 2023 found that aspirin was less effective than oral anticoagulants in preventing VTE after major orthopedic surgery, but had a lower risk of bleeding complications 6.
Another study found that preinjury aspirin use was associated with a significant protective effect against DVT in trauma patients, particularly when used in combination with heparinoid prophylaxis 4.

The efficacy of aspirin for DVT prophylaxis has been compared to other anticoagulants, such as low molecular weight heparins and warfarin, with mixed results 3, 7, 6.
Aspirin has been found to be less efficacious than low molecular weight heparins in some studies, but may be a reasonable alternative for patients who are at high risk of bleeding or have contraindications to other anticoagulants 3, 7.
The safety profile of aspirin for DVT prophylaxis is generally favorable, with a lower risk of major bleeding complications compared to oral anticoagulants 6.

Aspirin may be considered as a prophylactic agent for DVT in patients who are at high risk of VTE, such as those undergoing orthopedic surgery or who have had a previous episode of VTE 3, 5.
The use of aspirin for DVT prophylaxis should be individualized, taking into account the patient's risk factors for VTE and bleeding, as well as any contraindications to other anticoagulants 3, 6.
Further studies are needed to clarify the role of aspirin in DVT prophylaxis and to determine the optimal dosage and duration of treatment 3, 7, 6.