As discussed in Recommendation 3, patients who have a known bleeding disorder or active liver disease are at elevated risk for bleeding. Due to the serious complications that can occur in these patients, the work group deemed it appropriate to issue a consensus-based recommendation in spite of a lack of relevant, published data. It is the consensus of the work group that mechanical compressive devices are appropriate for these patients, as pharmacologic prophylaxis may exacerbate the risk of bleeding. Using mechanical compressive devices is of low risk and consistent with current practice. Consultation with a hematologist or other specialist may be warranted in some cases, especially when a patient is both at an elevated risk of bleeding and at an elevated risk of VTED.