The subject of the study is to compare the analgesic efficacy of transversalis fascia plan block and erector spina plane block applied with ultrasonography in patients who have undergone inguinal hernia operation. The aim of the study is to compare two different regional anesthesia methods applied in the postoperative period in terms of 24-hour opioid consumption, pain scores, additional analgesic need, and side effects and complications in the postoperative period.

An identification number (ID) number will be randomly assigned to each patient, whose written consent was obtained before the surgery, when they are admitted to the postoperative recovery room. In the postoperative period, patients will be followed up with these numbers in patient follow-up. Which group the patients will be included in will be determined by the closed envelope method.

The anesthetist, who will perform the regional block, will give the block to be applied in a sealed envelope by an assistant staff outside the study, and at the same time, the patient will not know which block has been made. The anesthesiologist who made the block will not participate in the pain follow-up of the patients. Postoperative pain assessment and data collection will be performed by another investigator blinded to the study.

Spinal anesthesia will be applied to all patients and inguinal hernia operation will be appropriate. Patients taken to the recovery room will be divided into two groups. Transversalis fascia plan block (Group T) will be applied to the patients in a group after local cleansing of the skin area, accompanied by ultrasonography. The patients in the other group will be treated with an erector spina plane block (Group E) following local cleansing of the skin area, accompanied by ultrasonography.

In both block management, 0.25% bupivacaine (Buvasin Vem İlaç, Turkey) (15 ml physiological saline + 15 ml 0.5% bupivacaine) total amount of 30 ml, same volume and same concentration will be used.

After the block procedure, the patient will be observed in the recovery room for side effects. Patient-controlled analgesia (PCA) will be used as a standard in the treatment of postoperative pain in patients in both groups without any complications. Tramadol HCL, which is routinely used for postoperative pain control for PCA, will be used (3 mg/ml, total volume 100 mL).

Evaluation of postoperative pain will be done with numerical rating scale (NRS).Pain levels will be questioned in two different ways as rest and cough.

Inclusion Criteria:

• Those who underwent unilateral inguinal hernia surgery under elective conditions
• 18-65 years
• ASA I-III
• Patients with written consent who agreed to participate in the study

Exclusion Criteria:

• Body mass index > 35 kg/m²,
• Coagulopathy and local infection or hematoma in the area to be blocked,
• Allergic to a local anesthetic agent or one of the drugs used in the study,
• Those with a history of chronic opioid and corticosteroid use,
• Unable to use the patient-controlled analgesia system,
• Those with psychiatric illness,
• Cases with a surgical time of less than 30 minutes and more than 120 minutes for better standardization of studies,
• Patients who do not agree to participate in the study will not be included in the study.

Researched data and statistical analyzes will be available from the journal in which the clinical study was published.

The patient will not know which study group he is in. The anesthetist, who will perform the regional block, will give the block to be applied in a sealed envelope by an assistant staff outside the study, and at the same time, the patient will not know which block has been made. The anesthesiologist who made the block will not participate in the pain follow-up of the patients. Postoperative pain assessment and data collection will be performed by another investigator blinded to the study.