Risk of bleeding may be increased; caution in patients with increased risk of bleeding (bacterial endocarditis; congenital or acquired bleeding disorders; active ulcerative or angiodysplastic GI diseases; severe uncontrolled hypertension; hemorrhagic stroke; or use shortly after brain, spinal, or ophthalmology surgery; in patients treated concomitantly with platelet inhibitors; recent GI bleeding; thrombocytopenia or platelet defects; renal impairment; hepatic impairment; hypertensive or diabetic retinopathy; or in patients undergoing invasive procedures). Risk of major bleeding may be increased if initial dose is administered earlier than recommended (initiation recommended at 6-8 hours following surgery). Do not administer with other agents that increase the risk of hemorrhage unless they are essential for the management of the underlying condition (e.g. warfarin for treatment of venous thromboembolism). Although considered an insensitive measure of fondaparinux activity, there have been postmarketing reports of bleeding associated with elevated APTT. Discontinue if bleeding occurs. Thrombocytopenia has occurred with administration, including reports of thrombocytopenia with thrombosis similar to heparin-induced thrombocytopenia (discontinue therapy if platelets fall to <100000/mm^3^). Use with caution in patients with moderate renal dysfunction (CrCl 30-50 mL/minute); contraindicated in patients with CrCl <30 mL/minute (discontinue if severe dysfunction or labile function develops). Patients with recent or anticipated neuraxial anesthesia (epidural or spinal anesthesia) are at risk of spinal or epidural hematoma and subsequent paralysis (risk is increased by concomitant agents which may alter hemostasis, as well as traumatic or repeated epidural or spinal puncture). The administration of fondaparinux is not recommended prior to and during primary percutaneous coronary intervention (PCI) in patients with STEMI, due to an increased risk for guiding-catheter thrombosis. Patients with UA/NSTEMI or STEMI undergoing any PCI should not receive fondaparinux as the sole anticoagulant. Following sheath removal, fondaparinux therapy should not resume for at least 2 hours in patients with UA/NSTEMI and 3 hours in patients with STEMI. Avoid administration 24 hours before and 48 hours after coronary artery bypass graft (CABG) surgery. Appropriate use for subcutaneous administration; not for I.M. administration.