Ultrasound-Guided PEC I vs SAP Block for Postoperative Analgesia in Modified Radical Mastectomy

Postoperative pain following modified radical mastectomy (MRM) is often moderate to severe and may negatively affect patient recovery, increase opioid consumption, and contribute to postoperative complications such as nausea, vomiting, and hemodynamic instability. Regional analgesic techniques have become an integral component of multimodal analgesia strategies aiming to improve pain control while minimizing opioid-related adverse effects. Among these techniques, ultrasound-guided Pectoral Nerve Block (PEC I ) and Serratus Anterior Plane Block (SAPB) have gained increasing attention for breast surgeries. This randomized double-blind controlled clinical trial was designed to compare the efficacy of ultrasound-guided PEC I block versus ultrasound-guided SAPB for postoperative analgesia in female patients undergoing modified radical mastectomy under general anesthesia. After obtaining approval from the Research Ethics Committee of the Faculty of Medicine, Ain Shams University, and written informed consent from all participants, a total of 64 female patients aged 35-60 years with ASA physical status I or II scheduled for MRM were enrolled. Patients were randomly allocated into two equal groups (32 patients each) using a computer-generated randomization sequence with sealed opaque envelopes to ensure allocation concealment. All patients received standardized general anesthesia. Following induction of anesthesia and under complete aseptic precautions, the assigned regional block was performed using ultrasound guidance. Patients in Group I received an ultrasound-guided PEC I block, where 20 ml of 0.25% bupivacaine was injected into the interpectoral plane between the pectoralis major and pectoralis minor muscles. Patients in Group II received an ultrasound-guided serratus anterior plane block, with 20 ml of 0.25% bupivacaine injected between the serratus anterior muscle and the external intercostal muscles. Postoperative pain intensity was assessed using the Numeric Rating Scale (NRS) for 24 hours. Hemodynamic parameters including heart rate and mean arterial blood pressure were recorded intraoperatively and postoperatively at predefined intervals. The results demonstrated that SAPB provided superior postoperative analgesia compared to PEC I block. Patients in the SAPB group experienced significantly lower pain scores during the first 6 postoperative hours, a significantly longer time to first rescue analgesia, and a significant reduction in total postoperative pethidine consumption. Furthermore, the SAPB group showed better hemodynamic stability during intraoperative and early postoperative periods, with significantly lower heart rate and mean arterial blood pressure. The incidence of postoperative nausea and vomiting was significantly higher in the PEC I group. These findings suggest that ultrasound-guided serratus anterior plane block is a more effective and safer regional analgesic technique than pectoral nerve block for postoperative pain management in patients undergoing modified radical mastectomy, offering improved analgesia, reduced opioid requirements, and fewer adverse effects.