This study aims to compare the efficacy of the ESP and SPSIP blocks in managing postoperative pain following breast surgery. Breast surgery, particularly after oncological and reconstructive procedures, often leads to significant postoperative pain. Effective pain control is crucial for accelerating recovery, reducing the risk of complications, and facilitating early discharge. Both ESP and SPSIP blocks involve the administration of local anesthetics into fascial plane spaces to achieve peripheral nerve blockade and control pain. This study will evaluate the effectiveness of these blocks in terms of pain scores, opioid consumption, and overall patient satisfaction to determine the optimal approach for postoperative pain management in breast surgery.

Breast surgery is one of the most frequently performed procedures, and effective postoperative pain management is critical to its success. Proper pain control not only facilitates early mobilization but also reduces the risks of pulmonary complications, deep vein thrombosis, and embolism. It helps prevent stress-induced endocrine and metabolic responses, shortens hospital stays, and lowers healthcare costs. Regional anesthesia is a highly effective strategy for postoperative pain control, minimizing opioid use and its associated side effects such as sedation, nausea, vomiting, and constipation.

Among the commonly used regional anesthesia techniques in breast surgery are the Erector Spinae Plane (ESP) block, Serratus Anterior Plane block, and Pectoral block. While the ESP block appears more effective, conflicting evidence exists regarding its efficacy in postoperative pain management, with variability in block spread across individuals. The recently introduced Serratus Posterior Superior Intercostal Plane (SPSIP) block, a periparavertebral block, offers a wider distribution range from C3 to T7 dermatomes, suggesting potential for more comprehensive postoperative analgesia in breast procedures.

The ESP block is performed under ultrasound guidance, using an in-plane technique to advance the needle from caudal to cranial (or vice versa), targeting the lateral part of the T6 transverse process, where local anesthetic is injected between the erector spinae muscle and the transverse process. For the SPSIP block, the needle is advanced between the second and third ribs towards the medial scapula, reaching the fascial plane between the serratus posterior superior muscle and the intercostal muscles. After hydrodissection confirms placement, local anesthetic is injected.

This study aims to compare the efficacy of ESP and SPSIP blocks in managing postoperative pain in breast surgery by evaluating pain scores, opioid consumption, and patient satisfaction. Since no study has yet directly compared these blocks, the findings will make a significant contribution to the existing literature.

Inclusion Criteria

• Age between 18 and 65 years.
• Scheduled for breast surgery (Modified Radical Mastectomy with or without axillary lymph node dissection, Mastopexy, Reduction Mammoplasty).
• Preoperative anesthesia risk classified as ASA I-III according to the American -Society of Anesthesiologists (ASA) classification.
• Patients who provide informed consent for participation in the study.

Exclusion Criteria

• History of coagulation disorders.
• Patients using aspirin or medically prescribed anticoagulants.
• Patients with severe systemic diseases (ASA IV).
• Patients undergoing emergency surgery.
• Patients younger than 18 or older than 65 years.
• Patients who do not develop adequate sensory block after the procedure.
• Presence of infection at the block site.
• Patients with thoracic deformities.
• Patients who decline to participate in the study.

Only individuals as female will be eligible to participate in this study, as the focus is on breast surgeries, which are performed on female patients.

The study will be conducted in a double-blind design. Neither the patients nor the researchers assessing pain management will know which treatment has been applied. The anesthesia team, present in the operating room and responsible for administering the blocks, will be aware of the group assignments, but the research team responsible for postoperative evaluations will not have access to this information. The operating room coordinator will assign each patient to the appropriate group according to a randomization list and will only share this information with the anesthesia team. The research team evaluating postoperative pain scores and collecting data will do so without knowledge of the patients' treatment group, ensuring objectivity in the assessments through blinding.