What is the PECS II (Pectoral Nerve Block II) peripheral nerve block?

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Last updated: March 11, 2026 • View editorial policy

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What is the PECS II Peripheral Nerve Block?

The PECS II (Pectoral Nerves Block Type II) is a fascial plane block that involves injecting local anesthetic between the pectoralis major and minor muscles (PECS I component) plus an additional injection between the pectoralis minor and serratus anterior muscles to anesthetize the pectoral nerves, intercostobrachial nerve, intercostal nerves III-VI, and the long thoracic nerve for breast and chest wall surgery. 1

Anatomical Technique

The block consists of two injection sites:

  • First injection (PECS I component): Local anesthetic is deposited in the fascial plane between the pectoralis major and minor muscles 1
  • Second injection (PECS II component): Local anesthetic is placed between the pectoralis minor and serratus anterior muscles at the level of the third rib 1, 2

The block is performed using ultrasound guidance to visualize the muscle layers and ensure accurate needle placement 1, 3, 2

Nerves Targeted

The PECS II block aims to anesthetize:

  • Medial and lateral pectoral nerves 3, 2
  • Intercostobrachial nerve 1, 4, 2
  • Lateral cutaneous branches of intercostal nerves III, IV, V, and VI 1, 2
  • Long thoracic nerve 1, 4, 2

Clinical Applications

Primary indications include:

  • Breast surgery: Modified radical mastectomy, lumpectomy, wide excisions, and breast reconstruction 1, 4, 5
  • Axillary procedures: Axillary clearance and lymph node dissection 1, 4, 2
  • Chest wall surgery: Non-breast-related thoracic procedures 3
  • Breast implant procedures: Subpectoral prosthesis placement and tissue expanders where pectoral muscle distension causes significant pain 2

Clinical Efficacy

Evidence from breast surgery demonstrates:

  • Reduced pain scores: PECS II blocks provide lower pain scores compared to no block or placebo, particularly in the first 2 postoperative hours 1
  • Decreased opioid consumption: Both intraoperative fentanyl and postoperative morphine requirements are significantly reduced 1, 4, 5
  • Comparable to paravertebral block: Meta-analyses show similar pain relief and analgesic consumption between PECS and paravertebral blocks 1
  • Time-limited superiority: PECS II provides better early analgesia (first 2-18 hours), but paravertebral blocks demonstrate superior pain control after 18 hours 1

Guideline Recommendations

According to the 2020 PROSPECT guidelines for oncological breast surgery:

  • PECS blocks are recommended (Grade A) for major breast surgery when axillary node dissection is not performed or when paravertebral block is contraindicated 1
  • Paravertebral block remains the preferred technique for major breast surgery with axillary dissection due to more reliable T1 nerve coverage 1
  • PECS blocks may be combined with local anesthetic wound infiltration for comprehensive coverage 1

Important Caveats

Critical limitations to understand:

  • Incomplete axillary coverage: Neither PECS nor paravertebral blocks reliably provide sufficient analgesia to the axilla (T1 nerve distribution) due to anatomical reasons 1
  • Injection site matters: Conventional PECS II (between pectoralis minor and serratus anterior) provides superior axillary spread compared to subserratus plane injection deep to serratus anterior 6
  • Inferior to erector spinae plane block: After the first postoperative hour, erector spinae plane blocks demonstrate lower pain scores and opioid consumption compared to PECS blocks 1

Technical Considerations

For optimal results:

  • The block is described as simple and easy to learn with ultrasound guidance 4, 2
  • Common local anesthetics used include bupivacaine and ropivacaine 7, 1
  • The technique can serve as an alternative or rescue block when paravertebral blocks or thoracic epidurals fail 2
  • No significant block-related complications have been reported in clinical trials 5

References

2
Research

Ultrasound description of Pecs II (modified Pecs I): a novel approach to breast surgery.

Revista espanola de anestesiologia y reanimacion, 2012

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