Pectoralis (PECS) and Serratus Plane Blocks


The pectoralis (PECS) block and serratus plane block are regional anesthesia techniques that provide analgesia for the chest wall, particularly for breast or thoracic surgery. The nerve supply to the chest wall is complex, with the thoracic intercostal nerves providing most of the cutaneous innervation. The lateral cutaneous branches of the thoracic intercostal nerves will travel between the serratus anterior and pectoralis minor muscles before supplying the skin overlying the axilla and breast. The deeper fascial layers of the breast receive nerve supply from the lateral and medial pectoral nerves, which are branches of the brachial plexus. The lateral and medial pectoral nerves will travel between the pectoralis major and minor muscles.  

The PECS block will typically provide analgesic coverage of the breast and axilla. The serratus plane block will provide similar coverage but with more extensive coverage of the lateral chest wall.


PECS block: analgesia for breast or axilla surgery 

Serratus block: analgesia for breast, axilla, or thoracic surgery and analgesia for rib fractures

Block Technique

The Pectoralis blocks can be divided into two separate techniques. The PECS 1 block involves injection of local anesthetic between the pectoralis major and pectoralis minor muscles. The PECS 2 block includes the PECS 1 block with an additional deeper injection between the pectoralis minor and serratus anterior muscles. Both injections are performed at the level of the third or fourth rib along the anterior axillary line. The PECS 1 block is rarely performed on its own, as the PECS 2 provides better coverage of the breast and axilla. 

The serratus plane block is a similar technique that is performed further lateral and inferior to the PECS 2, with the injection placed in a plane deep to the serratus anterior muscle at the level of the fourth or fifth rib along the mid axillary line. The serratus plane block is thought to provide more lateral coverage of the chest wall.

Block Duration

For single shot techniques with long acting local anesthetics (bupivacaine or ropivacaine), analgesic duration is approximately 12 hours.

If a continuous technique is desired, then placement of a thoracic epidural should be considered for more prolonged analgesic needs. Catheter placement in the PECS or serratus planes are not commonly performed but can be considered in rare circumstances.

Special Considerations

Potential complications include incomplete coverage, hematoma, pneumothorax, and local anesthetic systemic toxicity. The long thoracic nerve is often anesthetized by the PECS or serratus plane blocks, which can confound the ability of a surgeon to check the integrity of the long thoracic nerve during axillary surgery.

Who do I contact if I feel my patient could benefit from a regional anesthesia technique?

When booking OR cases, surgeons can enter requests for regional anesthesia. The Department of Anesthesia schedules experienced providers to perform these blocks in all ORs. For regional anesthesia in inpatients reach out to the Acute Pain Service that covers your campus. 

Please see the link for the pain medicine consult services: - for-providers--request-consult-or-refer-a-patient


Abdallah FW, T Cil, D MacLean, C Madjdpour, J Escallon, J Semple, R Brull (2018). Too Deep or Not Too Deep? A Propensity-Matched Comparison of the Analgesic Effects of a Superficial Versus Deep Serratus Fascial Plane Block for Ambulatory Breast Cancer Surgery. Regional Anesthesia and Pain Medicine. 43(5): 480-487.

Abdallah FW, D MacLean, C Madjdpour, T Cil, A Bhatia, R Brull (2017). Pectoralis and Serratus Fascial Plane Blocks Each Provide Early Analgesic Benefits Following Ambulatory Breast Cancer Surgery: A Retrospective Propensity-Matched Cohort Study. Anesthesia & Analgesia. 125 (1): 294-302.

Blanco R, T Parras, JG McDonnell and A Prats-Galino (2013). Serratus plane block: a novel ultrasound-guided thoracic wall nerve block. Anaesthesia. 68: 1107-1113.

Bashandy GM, Abbas DN. Pectoral nerves I and II blocks in multimodal analgesia for breast cancer surgery: a randomized clinical trial. Reg Anesth Pain Med. 2015;40(1):68-74.

Chiu, C., Aleshi, P., Esserman, L.J. et al. Improved analgesia and reduced post-operative nausea and vomiting after implementation of an enhanced recovery after surgery (ERAS) pathway for total mastectomy. BMC Anesthesiol 18, 41 (2018).