The Day Begins: Pre-Anesthesia Clinic

The pre-anesthesia clinic is bustling with preparations for a diverse surgical roster, including orthopedic joint replacements, oncologic resections, and cardiac procedures. Regional anesthesia (RA) offers significant advantages—opioid-sparing analgesia, faster recovery, and reduced hospital stays. However, many patients are on antithrombotic therapy, which raises the risk of catastrophic complications such as epidural hematomas or deep plexus hemorrhages. These bleeding events, if not decompressed promptly, may result in irreversible neurologic injury such as paraplegia.

Meeting the Patients: A Spectrum of Antithrombotics

Examples of patients commonly encountered include:

• A 78-year-old on apixaban for atrial fibrillation, requiring a femoral nerve block for knee replacement.
• A 65-year-old on enoxaparin (LMWH) for DVT prophylaxis after orthopedic surgery, planned for a paravertebral block for mastectomy.
• A 55-year-old on dual antiplatelet therapy (clopidogrel and aspirin) following coronary stenting, awaiting hip fracture repair, where a lumbar plexus block is being considered.

For each case, the indication, dose, half-life, clearance (especially renal), and reversibility of the antithrombotic must be evaluated. Renal impairment or polypharmacy may prolong effects unpredictably. Bleeding into closed or non-compressible spaces, particularly around the spinal canal or deep plexus structures, poses a devastating risk.

Why Anticoagulation Guidelines Matter in Regional AnesthesiaBenefits of RA

• Reduces opioid use.
• Improves postoperative recovery.
• Shortens hospital stay.

Reasons for Strict Guidelines

• Catastrophic complications: Epidural or spinal hematomas may cause paralysis unless decompressed within 6–12 hours. Deep plexus blocks (lumbar plexus, paravertebral) also carry high bleeding risks.
• Critical timing: Antithrombotics vary in half-life, clearance, reversibility, and renal dependence. Regional anesthesia must coincide with minimal drug activity.
• Increasing prevalence: Widespread use of DOACs, DAPT, and LMWH requires careful drug-specific planning.
• Medico-legal responsibility: ASRA-ESRA guidelines form the standard of care. Documentation, informed consent, and risk discussion are mandatory.

The Current Standard: ASRA-ESRA 2025 Guidelines

The 5th Edition of the ASRA-ESRA Guidelines (2025) provides a structured framework:

• Timing: Hold times depend on half-life, renal clearance, and drug reversibility.
• Risk stratification of block types:
• High risk: neuraxial, lumbar plexus, paravertebral.
• Intermediate risk: femoral, adductor canal.
• Low risk: superficial fascial plane blocks (e.g., TAP, ESP, SCB).
• Interdisciplinary input: Coordination with cardiologists, surgeons, and hematologists is essential.
• Documentation and consent: Explicit records protect against medico-legal risks.
• Lab monitoring: Drug-specific assays (e.g., anti-Xa, thrombin time, platelet counts) are emphasized.

What’s New in the 2025 Guidelines

Key updates compared with 2018 include:

• Dosing terminology: Shift from “prophylactic vs therapeutic” to “low-dose vs high-dose.”
• DOAC timing: Hold 72–120 hours, adjusted for renal function.
• LMWH: Emphasis on anti-Xa monitoring in renal dysfunction.
• Laboratory use: Encouragement of assays for DOACs and renal impairment cases.
• Block stratification: Explicit risk-based classification.
• Reversal agents: Guidance on antidotes such as idarucizumab (dabigatran) and andexanet alfa (Xa inhibitors).
• Catheter removal: Based on anti-Xa thresholds (<0.1 IU/mL for LMWH).

Laboratory Investigations in Antithrombotic PatientsUnfractionated Heparin (UFH)

• aPTT: Delay RA if >35 seconds; safe 4–6 hours after last dose.
• Platelets: Monitor for HIT if <100,000/µL.
• Anti-Xa: Safe when <0.1 IU/mL.

Low Molecular Weight Heparin (LMWH)

• Platelets: Stop LMWH and investigate HIT if <100,000/µL.
• Creatinine/eGFR: Extend hold times if <30 mL/min.
• Anti-Xa: Delay RA until <0.1 IU/mL.

Warfarin

• INR: Safe when ≤1.4.
• Management: Hold 5–7 days; use vitamin K or FFP if urgent reversal required.

Direct Oral Anticoagulants (DOACs: apixaban, rivaroxaban, edoxaban)

• Creatinine clearance: Extend hold times if <50 mL/min.
• Anti-Xa levels: Safe when <30 ng/mL.
• PT/INR/aPTT: Not reliable.

Dabigatran

• Renal clearance critical: Hold 72–120 hours depending on CrCl.
• Thrombin time or ecarin clotting time: Confirm absence of activity before RA.
• Idarucizumab available for reversal.

Antiplatelets

• Aspirin: Safe alone.
• Clopidogrel/Ticagrelor/Prasugrel: Require 5–10 day hold before RA, depending on drug.
• Platelet function testing: Useful in high-risk cases.

Perioperative Antithrombotic Management

• Aspirin/NSAIDs: No delay needed.
• Clopidogrel: Hold 5–7 days.
• Prasugrel: Hold 7–10 days.
• Ticagrelor: Hold 10 days.
• UFH: Wait 4–6 hours after last dose.
• LMWH: Hold 12 hours (low dose), 24 hours (high dose).
• Fondaparinux: Hold 36–105 hours depending on renal function.
• DOACs: Hold ≥72 hours, longer in renal impairment.
• Dabigatran: 72–120 hours depending on renal clearance.
• Thrombolytics: Avoid RA within 48 hours.

Challenging Scenarios

• Recent DOAC ingestion: Avoid neuraxial; consider GA or superficial blocks; reversal with andexanet alfa or idarucizumab.
• Mechanical valve with LMWH bridging: Delay until anti-Xa <0.1 IU/mL; avoid catheters.
• Post-stenting on DAPT: Avoid neuraxial; consider superficial blocks such as ESP or TAP.
• CKD patients: Extend DOAC hold; confirm with drug levels.
• Emergency surgery: GA or superficial blocks safer; coordinate reversal if urgent.

Special Populations

• Elderly: Reduced clearance; favor superficial blocks with lab confirmation.
• Neurosurgical patients: Avoid neuraxial; strict LMWH protocols.
• CKD: Extended hold times; anti-Xa monitoring essential.
• Obese patients: Ultrasound guidance preferred.
• Pediatric: Individualize; confirm drug clearance before RA.

Documentation: Safety and Medico-Legal Protection

Documentation should include:

1. Patient and procedure details (demographics, surgery, planned block).
2. Antithrombotic details (drug, dose, indication, last dose timing, renal function, lab values).
3. Risk assessment (block category, hold times, lab monitoring, catheter plan).
4. Multidisciplinary input (surgeon, cardiologist, hematologist, nephrologist).
5. Patient counseling and consent (verbal and written, bleeding risks explained).
6. Final anesthesia plan (chosen block, precautions, antithrombotic restart timing).

Take-Home Points

• Perform RA only when antithrombotic activity is minimal (anti-Xa <0.1 IU/mL, INR ≤1.4).
• Tailor decisions to drug type, block risk, renal clearance, and laboratory results.
• Avoid high-risk blocks in anticoagulated patients unless drug effect is absent.
• Laboratory monitoring is critical in DOACs, renal impairment, and high-risk procedures.
• Fixed hold times are not sufficient; context and patient-specific factors must guide decisions.
• Interdisciplinary coordination is essential.
• Comprehensive documentation ensures both patient safety and medico-legal protection.