For most surgical procedures, anticoagulation can be safely instituted after 1 2-24 hours of demonstrated hemostasis. Some situations may temper that interval, including the nature of the operation, for example neurosurgery where bleeding into a closed space can be disastrous or when there is an ongoing difficulty with bleeding at the operative site. In low-risk patients, warfarin therapy can be restarted with a daily dose of 5 mg until the INR is above 2.0. This patient is at somewhat greater risk due to her complicating illnesses (atrial fibrillation and a heart murmur), and therefore probably should be considered for bridging therapy with unfractionated heparin, starting 1 2-24 hours after surgery and continuing until the INR is in a therapeutic range for 1 -2 days. She can then return to her maintenance warfarin dose. Cardiac ultrasound imaging to determine any valvular abnormality would assist in that decision. Instead of unfractionated heparin, some high-risk patients may be managed with a daily prophylactic dose of LMWH over the 3-5 days of reinstituting warfarin to establish a therapeutic INR. This may be especial ly useful for surgeries with increased thrombogenic potential, such as hip or knee replacement.