Comparison of Serratus Posterior Superior Intercostal Plane Block and Rhomboid Intercostal Block in Patients Undergoing Breast Cancer Surgery

This randomized clinical trial aims to evaluate and compare the analgesic efficacy of the Serratus Posterior Superior Intercostal Plane (SPSIP) and Rhomboid Intercostal Block in patients undergoing Breast Cancer Surgery With Axillary Lymph Node Dissection. The primary outcome is Visual Analog Scale (VAS) during the first 24 hours after surgery. Secondary outcomes include total opioid consumption, requirement for rescue analgesia, block performance time, block-related and systemic side effects (hematoma, pneumothorax, local anesthetic toxicity, vascular puncture, infection), Patient satisfaction assessed using a Likert scale, quality of recovery assessed using the QoR-15 questionnaire.

Inclusion Criteria: * Female patients aged 18-65 years * ASA physical status I-III * Scheduled for elective breast cancer surgery with axillary lymph node dissection * Body mass index (BMI) between 18 and 35 kg/m² * Ability to understand and use the patient-controlled analgesia (PCA) device * Ability to provide written informed consent Exclusion Criteria: * Refusal to participate * Allergy to local anesthetics * Infection at the injection site * Coagulopathy or ongoing anticoagulant therapy * Chronic opioid use or opioid dependence * Severe hepatic or renal insufficiency * Pregnancy or breastfeeding * Cognitive impairment or inability to communicate pain scores * Body mass index (BMI) \35 kg/m²