For a 63‑year‑old woman on warfarin (Coumadin) for a prior pulmonary embolism who requires two hip/back injections, how should warfarin be held and what low‑molecular‑weight heparin (LMWH) bridging regimen should be used?

Warfarin Interruption and LMWH Bridging for Procedural Anticoagulation

Direct Answer

For this 63-year-old woman on warfarin for prior pulmonary embolism requiring two hip/back injections, stop warfarin 5 days before the procedure, start therapeutic-dose LMWH on day 3 pre-procedure, give the last LMWH dose at half the daily dose 24 hours before the procedure, and resume full-dose LMWH 48-72 hours post-procedure given the high bleeding risk of spinal/paraspinal injections. 1

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Pre-Procedure Warfarin Interruption Protocol

Timing of Warfarin Cessation

• Stop warfarin 5-6 days before the procedure to allow adequate time for INR normalization 1
• Check baseline labs (hemoglobin, platelet count, creatinine, INR) 7-10 days before the procedure 1
• Assess INR the day before the procedure; proceed only if INR ≤ 1.5 1
• If INR is 1.5-1.8 on the day before procedure, consider low-dose oral vitamin K reversal (1-2 mg) 1

When to Initiate LMWH Bridging

• Start therapeutic-dose LMWH 3 days before the procedure (after warfarin has been stopped for 2-3 days) 1
• The last pre-procedural LMWH dose should be administered no less than 24 hours before surgery at half the total daily dose 1

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LMWH Dosing Regimens

Therapeutic-Dose Options

• Enoxaparin: 1 mg/kg subcutaneously twice daily OR 1.5 mg/kg once daily 1
• Dalteparin: 100 IU/kg subcutaneously twice daily OR 200 IU/kg once daily 1
• Tinzaparin: 175 IU/kg subcutaneously once daily 1

Why LMWH is Used for Bridging

• LMWH provides predictable anticoagulation with a shorter half-life (14-17 hours) compared to warfarin (42 hours), allowing precise peri-procedural control 1, 2
• LMWH has more predictable pharmacokinetics than unfractionated heparin and does not require aPTT monitoring in most patients 2
• For patients with prior pulmonary embolism, the risk of recurrent thromboembolism during the brief interruption of anticoagulation is substantial, necessitating bridging therapy 1

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Post-Procedure Resumption Protocol

High Bleeding Risk Procedures (Spinal/Paraspinal Injections)

Hip and back injections, particularly if epidural or near the spinal canal, are considered high bleeding risk procedures. 1

• Day 0-1 (day of procedure): Resume warfarin at maintenance dose on the evening of or morning after the procedure 1
• Day 1 post-procedure: Do NOT restart LMWH; continue warfarin only 1
• Day 2-3 post-procedure: Restart LMWH at the previous therapeutic dose (48-72 hours after the procedure) 1
• Day 4 post-procedure: Check INR; discontinue LMWH if INR > 1.9 1
• Day 7-10 post-procedure: Recheck INR to ensure therapeutic range (2.0-3.0) 1

Target INR for Pulmonary Embolism

• Maintain INR between 2.0-3.0 (target 2.5) throughout long-term anticoagulation 3, 4, 5

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Critical Pitfalls to Avoid

Timing Errors

• Never give LMWH within 24 hours of a high bleeding risk procedure, as this significantly increases hemorrhagic complications 1
• Never resume full-dose LMWH immediately after spinal/paraspinal procedures; wait 48-72 hours to assess for bleeding 1
• Never stop LMWH before INR is therapeutic (≥2.0) for at least 24 hours when resuming warfarin, as this creates a dangerous anticoagulation gap 3, 4

Monitoring Failures

• Check INR before the procedure to confirm it is ≤1.5; proceeding with elevated INR risks serious bleeding 1
• Do not assume warfarin has cleared after 5 days without checking INR, especially in elderly patients or those with hepatic dysfunction 1

Special Considerations for This Patient

• Given her history of pulmonary embolism (high thrombotic risk), bridging with therapeutic-dose LMWH is mandatory—do not use prophylactic doses 1
• If the patient has renal impairment (creatinine clearance <30 mL/min), consider unfractionated heparin instead of LMWH or use anti-Xa monitoring 6, 7
• Platelet count should be monitored during LMWH therapy to detect heparin-induced thrombocytopenia 6

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Summary Timeline

Day	Action
Day -7 to -10	Assess patient, check baseline labs (Hgb, platelets, creatinine, INR) [1]
Day -5 or -6	Stop warfarin [1]
Day -3	Start therapeutic-dose LMWH (e.g., enoxaparin 1 mg/kg twice daily) [1]
Day -1	Give last LMWH dose at half the daily dose, at least 24 hours before procedure; check INR (must be ≤1.5) [1]
Day 0	Perform procedure; resume warfarin at maintenance dose that evening [1]
Day 1	Continue warfarin only; no LMWH [1]
Day 2-3	Restart full-dose LMWH (48-72 hours post-procedure) [1]
Day 4	Check INR; stop LMWH if INR >1.9 [1]
Day 7-10	Recheck INR to confirm therapeutic range [1]