Pectoral Nerve Block and Serratus Posterior Superior Intercostal Plane Block in Breast Cancer Surgery

Patients in this group will receive an ultrasound-guided Serratus Posterior Superior Intercostal Plane (SPSIP) block with 30 mL of 0.25% bupivacaine hydrochloride injected into the fascial plane between the serratus posterior superior muscle and the third rib, 30 minutes before surgery.

Patients in this group will receive an ultrasound-guided PECS II block with 30 mL of 0.25% bupivacaine hydrochloride (20 mL between the pectoralis minor and serratus anterior muscles, and 10 mL between the pectoralis major and minor muscles), 30 minutes before breast cancer surgery.