How many hours before an operation should fondaparinux (a selective Factor Xa inhibitor) be stopped?

Fondaparinux Discontinuation Before Surgery

Fondaparinux should be stopped more than 36 hours before elective surgery. 1

Standard Preoperative Timing

• The last injection of fondaparinux must be given more than 36 hours before surgery to allow adequate clearance of anticoagulant effect 1, 2
• This timing is based on fondaparinux's half-life of approximately 17 hours, requiring roughly 2 half-lives for sufficient drug elimination 1, 3
• For CABG specifically, the American College of Cardiology recommends discontinuing fondaparinux 24 hours before surgery and transitioning to unfractionated heparin 1, 2

Special Considerations for Neuraxial Procedures

• For neuraxial procedures (spinal/epidural anesthesia), fondaparinux requires a longer discontinuation period of more than 48 hours 1
• The target is to achieve anti-Xa levels below the detection threshold (<0.1 mg/mL or <0.1 U anti-Xa/mL) before performing these high-risk procedures 1
• This extended timeframe is critical because spinal or epidural hematomas can result in permanent paralysis 4

Clinical Evidence Supporting 36-Hour Window

• A comparative study of fondaparinux versus enoxaparin in CABG patients demonstrated significantly higher postoperative bleeding when fondaparinux was discontinued less than 36 hours before surgery compared to more than 36 hours 5
• This finding validates the guideline recommendation and provides direct clinical evidence for the 36-hour cutoff 5

Bridging Strategy for High-Risk Patients

• In patients with acute heparin-induced thrombocytopenia (HIT) requiring surgery within 1 month of diagnosis, the long half-life of fondaparinux creates high thrombotic risk during the extended discontinuation period 1
• For these high-risk patients, consider switching to shorter-acting agents (argatroban or bivalirudin) rather than using fondaparinux perioperatively 1
• Argatroban requires only 4 hours discontinuation and bivalirudin only 2 hours, providing safer perioperative management 1

Postoperative Resumption

• Fondaparinux can be restarted from the 6th postoperative hour after bleeding risk assessment 1
• The FDA label specifies the initial postoperative dose should be given no earlier than 6 to 8 hours after surgery once hemostasis is established 4
• Administration earlier than 6 hours significantly increases major bleeding risk 4

Critical Pitfalls to Avoid

• Do not use the 24-hour discontinuation window recommended for CABG bridging protocols as a general rule—this applies only when transitioning to unfractionated heparin for cardiac surgery 1, 2
• Do not confuse fondaparinux timing with shorter-acting anticoagulants like enoxaparin (12-24 hours) or bivalirudin (3 hours) 1, 2
• In patients with renal impairment (CrCl 30-50 mL/min), anticoagulant effects persist even longer than the standard 36-hour window due to reduced clearance 4
• After discontinuation, anticoagulant effects may persist 2-4 days in patients with normal renal function and even longer with renal impairment 4