When to hold therapeutic Low Molecular Weight Heparin (LMWH) prior to surgery?

From the Guidelines

Therapeutic low molecular weight heparin (LMWH) should be held 24 hours before surgery for most procedures, as recommended by the most recent guidelines 1. When to hold therapeutic LMWH prior to surgery is a critical decision that balances the risk of thromboembolism against the risk of perioperative bleeding.

Key Considerations

• For patients receiving twice-daily therapeutic doses (such as enoxaparin 1 mg/kg twice daily), the last dose should be given the morning of the day before surgery.
• For once-daily dosing regimens (such as enoxaparin 1.5 mg/kg daily), the last dose should be given 24 hours before the procedure.
• The timing recommendations are based on the pharmacokinetics of LMWH, which has a half-life of approximately 4-7 hours in patients with normal renal function, with peak anti-Xa activity occurring 3-5 hours after administration 1.

Special Considerations

• For high bleeding risk procedures (neurosurgery, cardiac surgery, or major spine surgery), LMWH should be held for 48 hours before surgery.
• For patients with renal impairment (creatinine clearance <30 mL/min), the holding period should be extended to 48 hours due to delayed drug clearance.

Resumption of Therapeutic LMWH

• Resumption of therapeutic LMWH typically occurs 24-72 hours after surgery, depending on the bleeding risk of the procedure and adequate hemostasis, often starting with prophylactic dosing before returning to therapeutic levels 1. The most recent and highest quality study 1 suggests administering the last pre-operative LMWH bridging dose at approximately 24 hours over administering the last dose 10 to 12 hours before a surgery/procedure, which aligns with the general recommendation to hold therapeutic LMWH 24 hours before surgery for most procedures.

From the FDA Drug Label

1. 6 Low-Dose Prophylaxis of Postoperative Thromboembolism

The most widely used dosage has been 5,000 units 2 hours before surgery and 5,000 units every 8 to 12 hours thereafter for 7 days or until the patient is fully ambulatory, whichever is longer.

The therapeutic LMWH (Low Molecular Weight Heparin) should be held prior to surgery, but the provided label is for heparin, not LMWH. However, based on the information for low-dose prophylaxis of postoperative thromboembolism, it can be inferred that the dose is typically administered 2 hours before surgery.

• It is essential to note that the label provided is for heparin, not LMWH.
• The decision to hold therapeutic LMWH prior to surgery should be based on the specific LMWH product being used and the patient's individual clinical situation.
• As the label does not directly address the question for LMWH, the information provided is not directly applicable to LMWH 2.

From the Research

Therapeutic LMWH and Surgery

When to hold therapeutic Low-Molecular-Weight Heparin (LMWH) prior to surgery is a critical decision that depends on various factors, including the type of surgery, patient's risk of thromboembolism, and bleeding risk.

• The decision to hold LMWH should be based on the patient's individual risk factors and the type of surgery they are undergoing.
• According to 3, LMWH is often used as bridging therapy in patients on long-term oral anticoagulants who require temporary interruption of anticoagulation for surgery.
• The study found that LMWH was associated with similar rates of adverse events, including thromboembolism and bleeding, compared to unfractionated heparin.

Timing of LMWH Discontinuation

The timing of LMWH discontinuation prior to surgery is crucial to minimize the risk of bleeding.

• There is no specific guideline on when to hold therapeutic LMWH prior to surgery, but it is generally recommended to discontinue LMWH 12-24 hours before surgery, depending on the patient's renal function and the type of surgery.
• A study by 4 compared the use of LMWH and unfractionated heparin in critically ill COVID-19 patients and found that therapeutic anticoagulation conveyed no survival benefit over prophylactic anticoagulation.
• Another study by 5 found that LMWH does not appear to bioaccumulate based on repeated measurements of trough anti-Xa levels, and thrombocytopenia occurred in 9.3% of patients receiving LMWH.

Patient-Specific Factors

Patient-specific factors, such as renal function and bleeding risk, should be taken into account when deciding when to hold therapeutic LMWH prior to surgery.

• A study by 6 found that long-term LMWH was associated with less bleeding compared to vitamin K antagonist therapy in patients with proximal vein thrombosis.
• Another study by 7 found that enoxaparin, a type of LMWH, was more effective than unfractionated heparin in reducing the risk of death, myocardial infarction, or angina relapse in patients with unstable angina or non-Q-wave myocardial infarction.