Breast cancer is the most common malignancy in women. Modified radical mastectomy, a surgical procedure in the treatment of breast cancer, is one of the standard treatments. Postoperative pain can seriously reduce the quality of life in patients, and inadequately treated acute pain can trigger chronic pain syndrome. Therefore, thoracic paravertebral block and thoracic epidural block are effective in postoperative analgesia. However, the use of these blocks is limited due to complications. In recent years, less invasive blocks, such as pectoral nerve block (PECS I-II), Serratus anterior plane block (SAPB), Erector spinae plane block (ESPB), and Serratus Posterior Superior intercostal Plane Block (SPSİPB) have been applied. In this study, it was aimed to compare the analgesic effectiveness of ESPB and SPSİPB applications in patients undergoing breast surgery.

Postoperative pain will be assessed during resting and coughing with a visual analog scale (0-10 cm) and nausea and vomiting with a Postoperative Nausea Vomiting Score at the postoperative 1, 4, 8, 12, and 24 hours. The amount of tramadol consumed in the postoperative period will be recorded. Patient satisfaction will be assessed with the Likert scale at postoperative 24 hours.

Inclusion Criteria:

• Those aged 18-65
• Those with ASA scores I-II-III
• Those with a body mass index (BMI) between 18-35
• Patients who will undergo breast surgery

Exclusion Criteria:

• Those under the age of 18 and over the age of 65
• Those with ASA score IV and above
• Those with a history of allergy to the drugs to be blocked
• Those with a history of bleeding diathesis
• Patients with infection in the area to be blocked
• Those with a BMI below 18 and above 35
• Patients who underwent surgery under emergency conditions