After obtaining ethical committee approval from Kahramanmaras University Anesthesiology and Reanimation Department and Urology Clinic, 60 patients between 18-65 years old who meet ASA I-II classification criteria with body mass index ≤40 will be informed about this study both verbally and in writing prior to their inclusion in this study using a randomization method according to Helsinki Declaration after obtaining their written consent. Patients who cannot give consent due to any reason or have allergy history against local anesthetics or contraindications for peripheral nerve blocks (local infection,coagulopathy etc.) or psychiatric disorders or receiving antipsychotic drugs will be excluded from this study. Routine preoperative evaluation including age, height, and weight measurements will be performed on all patients at pre-anesthesia clinic.

Patients will be randomized into three groups: Group K, who will receive analgesia with patient-controlled analgesia (PCA) with tramadol only; Group E20, who will receive PCA with 20cc volume of ESP block; and Group E30, who will receive PCA with 30cc volume of ESP block. After standard general anesthesia induction and endotracheal intubation, one of the three analgesic methods will be randomly applied, and the surgery will commence. All patients will receive patient-controlled analgesia. Patients in Group K will not receive any local anesthetic injection. When the patient is transferred to the postoperative care unit, intravenous PCA device will be attached, and pain scores using Visual Analog Scale (VAS), rated from 0 (no pain) to 10 (worst pain ever experienced), at rest and during coughing will be evaluated at 2, 4, 6, 12, 18, and 24 hours postoperatively. The values will be recorded. When the patient experiences pain, analgesic agents will be administered according to the patient-controlled analgesia protocol. The time of first analgesic requirement and total amount of consumed analgesic agent within 24 hours will be recorded. Postoperative QUIPS: Quality Improvement in Postoperative Pain Management questionnaire will be administered, and side effects such as nausea/vomiting or sedation will be noted. Additionally, patient satisfaction regarding these methods and their willingness for repeat surgery or recommendation level on a scale from poor to excellent (very poor/poor/fair/good/excellent)will also be evaluated and recorded

Inclusion Criteria:

• between 18-65 years old
• ASA I-II classification
• Body mass index ≤40
• Helsinki Declaration after obtaining their written consent
• Patients undergoing Retrograde Intrarenal Surgery

Exclusion Criteria:

• Allergy history against local anesthetics
• Contraindications for peripheral nerve blocks (local infection,coagulopathy etc.)
• Psychiatric disorders or receiving antipsychotic drugs
• Patients with contraindications for spinal anesthesia,
• Coagulopathy,
• Known allergies to the drugs to be used,
• Infection at the site of the procedure,
• Dermatological diseases such as psoriasis that prevent aseptic preparation of the skin at the injection site,
• Septicemia or bacteremia,
• Shock or severe hypovolemia,
• Patients who are not volunteers