From the Guidelines

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

Aspirin is expected to reduce the risk of recurrent VTE by about one-third, which is less effective than anticoagulants 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, but it should be balanced against the risk of bleeding and inconvenience 1.
A study found that aspirin 100 mg once daily reduced the risk of recurrence in patients with unprovoked VTE after an initial treatment period of 6 to 18 months with a vitamin K antagonist 1.
The effectiveness of aspirin or other antiplatelet drugs to prevent VTE has been studied in relatively few hospitalized medical patients, and the results are limited by small numbers of outcome events and lack of reporting of rates of bleeding 1.

Benefits: reduced risk of recurrent VTE, low cost, oral administration, and low bleeding rates.
Risks: bleeding, inconvenience, and less effective than anticoagulants.

Aspirin should be considered in patients who are stopping anticoagulant therapy and do not have a contraindication to aspirin.
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.
Patients should be closely monitored for signs of bleeding and other adverse effects while taking aspirin for DVT prophylaxis.

The FDA Drug Labels for aspirin (PO) do not address this question.

From the Research

Aspirin has been shown to be effective in preventing deep vein thrombosis (DVT) in various patient populations, including those undergoing total hip replacement 2 and total knee arthroplasty 3, 4, 5.
A study published in 1986 found that aspirin reduced the incidence of phlebographic DVT in patients undergoing total hip replacement, with a significant reduction in DVT rates compared to the control group 2.
A 2024 meta-analysis found that aspirin was as effective as rivaroxaban in preventing VTE after primary total hip arthroplasty or total knee arthroplasty, with no significant difference in the incidence of VTE, PE, or major bleeding 3.
Another study published in 2016 found that preinjury aspirin use was associated with a reduced incidence of lower extremity DVT in trauma patients, particularly when used in combination with heparinoid prophylaxis 6.
Aspirin has been shown to be a safe and effective form of VTE prophylaxis after arthroplasty, with a low risk of bleeding complications and no requirement for routine blood tests 4, 5.

Aspirin has been compared to other anticoagulants, including low-molecular-weight heparin and rivaroxaban, and has been found to have a similar efficacy and safety profile 3, 5.
A 2020 systematic review and meta-analysis found that aspirin did not differ statistically significantly from other anticoagulants used for VTE prophylaxis after total hip and knee replacement, in terms of clinical effectiveness and safety profile 5.

The optimal dosage of aspirin for DVT prophylaxis is not well established, but studies have used doses ranging from 81-300 mg per day 3, 5.
Aspirin can be administered orally, and its use does not require routine blood tests or monitoring 4, 5.