Serratus vs ESP Block for Postoperative Pain in Unilateral Breast Surgery

Inclusion Criteria: * Female patients aged 18-65 years * ASA physical status I-III * Body mass index (BMI) between 18 and 35 kg/m² * Scheduled for elective unilateral breast surgery (mastectomy with or without sentinel lymph node biopsy) * Ability to understand and provide written informed consent Exclusion Criteria: * Infection at the site of block application * Known allergy to local anesthetics * Coagulopathy or anticoagulant therapy * Chronic opioid use * Pregnancy * Inability to communicate or cooperate * Refusal to participate * Failed block * Requirement of additional intraoperative analgesia outside the study protocol * Development of serious intraoperative complications