The study is planned as a single-center prospective randomized study and includes patients undergoing laparoscopic cholecystectomy. The aim of this study is to compare postoperative analgesic efficacy of erector spinae plane block and thoracic paravertebral block. Primary outcome is 24-hour postoperative opioid consumption.

All patients in the operating room receive the same anesthetic management under standard monitoring modalities. Both erector spinae plane block (ESPB) and thoracic paravertebral block (TPVB) are performed under ultrasound guidance at the T8 level using a linear probe and a longitudinal out-of-plane technique before induction of anesthesia. For ESPB, 10 mL of 0.375% bupivacaine is injected bilaterally between the deep fascia of the erector spinae muscle and the transverse process. For TPVB, 10 mL of 0.375% bupivacaine is injected bilaterally into the paravertebral space. After standard anesthesia induction, anesthesia is maintained with inhalation agents. Four milligrams of dexamethasone and 8 mg of ondansetron are administered for postoperative nausea and vomiting prophylaxis. As part of multimodal analgesia, all patients receive 1 g of paracetamol and 20 mg of tenoxicam.

All patients are followed according to a standardized postoperative analgesia protocol, which includes tramadol patient-controlled analgesia (10 mg bolus, 20-minute lockout). Postoperative static and dynamic pain scores are evaluated using the numeric rating scale (NRS) at 0, 1, 4, 6, 12, 18, and 24 hours. If the NRS score is greater than 3, 0.5 mg/kg meperidine is administered as rescue analgesia.

Inclusion Criteria:

• Elective cholecystectomy
• Age >18years
• American Society of Anesthesiologists classification I-III

Exclusion Criteria:

• Presence of contraindications for using regional anesthesia ( not having patient approval, bleeding diathesis or use of anticoagulants, infection at the injection site, and allergy to local anesthetics)
• Chronic analgesic use
• Open cholecystectomy or conversion to open cholecystectomy