What are the contraindications for a nerve block?

Contraindications for Nerve Blocks

Deep peripheral nerve blocks (infraclavicular, parasacral sciatic, posterior lumbar plexus) are absolutely contraindicated in patients taking P2Y12 inhibitors (clopidogrel, prasugrel, ticagrelor) unless discontinued 5-7 days prior to the procedure. 1

Absolute Contraindications

Anticoagulation-Related (High-Risk Blocks Only)

Deep/non-compressible blocks are contraindicated in the following scenarios:

• Active P2Y12 inhibitor therapy (clopidogrel, prasugrel, ticagrelor) without appropriate discontinuation periods 1

  • Clopidogrel: requires 5-day discontinuation
  • Prasugrel: requires 7-day discontinuation
  • Ticagrelor: requires 5-day discontinuation

• Therapeutic anticoagulation unless dabigatran concentration is ≤30 ng/mL or appropriate reversal (idarucizumab) is administered 1, 2

• Coagulopathy or bleeding disorders that cannot be corrected 1

Patient-Related Absolute Contraindications

• Patient refusal 1
• Active infection at the injection site 1
• Very short life expectancy (for interventional pain procedures) 1

Relative Contraindications Requiring Risk-Benefit Assessment

Antiplatelet Therapy (Block Type-Dependent)

For deep/high-risk blocks (infraclavicular, parasacral sciatic, posterior lumbar plexus):

• Aspirin monotherapy is a relative contraindication; may proceed only if benefit/risk ratio is favorable 1

For superficial/low-risk blocks (femoral, axillary, popliteal sciatic):

• Mono or dual antiplatelet therapy may be acceptable with favorable benefit/risk ratio 1
• These blocks can be compressed if bleeding occurs, making them safer in anticoagulated patients 1

Special Clinical Situations

• COVID-19 infection: Nasal sphenopalatine ganglion blocks should be avoided due to aerosol generation risk 1

• Medications increasing bleeding risk: Anticoagulants (warfarin, heparin), antiplatelet agents, and antiangiogenesis agents (bevacizumab) require careful assessment 1

• Respiratory compromise risk: Avoid blocks that may impair respiratory function (interscalene, supraclavicular) in favor of alternatives (axillary, infraclavicular, superior trunk blocks) 1

Critical Safety Requirements

Mandatory Technical Standards

All nerve blocks (superficial or deep) must be performed with:

• Ultrasound guidance to reduce local anesthetic systemic toxicity risk 1, 2
• Experienced operator performing the technique 1
• Calculated safe dose of local anesthetic based on patient weight 2, 3
• Immediate resuscitation equipment availability 2, 3

Perineural Catheter Considerations

Catheter insertion and removal follow the same contraindications as initial block placement:

• Must not compromise postoperative resumption of anticoagulants/antiplatelets 1
• Removal requires optimal hemostatic conditions 1
• Risk of infection, obstruction, migration, and accidental removal must be considered 4, 5

Common Pitfalls to Avoid

Do not assume aspirin is safe for all block types—it remains a relative contraindication for deep blocks requiring individual risk assessment 1

Do not perform deep blocks without knowing anticoagulation status—the inability to compress these areas makes hemorrhage potentially catastrophic 1

Do not proceed with blocks near the head/neck in COVID-19 patients without airborne precautions in addition to standard droplet precautions 1

Do not use general hemostasis guidelines for peribulbar blocks—compression is impossible if bleeding occurs, requiring special consideration despite low overall bleeding risk 1