The primary objective of this study is to demonstrate whether the Erector Spinae Plane Block provides effective analgesia in patients undergoing robotic colorectal surgery and whether it contributes positively to the postoperative process.

With the advantages of ultrasound in recent years, the application of regional anesthesia methods such as trunk and peripheral nerve blocks has become a crucial component of multimodal analgesia strategies in postoperative pain management. Among regional techniques, the erector spinae plane block, in particular, has been shown to provide effective analgesia after numerous surgeries in recent years and is increasingly being used. Because the erector spinae plane block provides effective analgesia in a wide range of thoracic and abdominal surgeries, such as thoracotomy, cholecystectomy, and bariatric surgery, and because it is a simple and safe block, it is gaining increasing acceptance in daily practice for the treatment of chronic and acute pain. The aim of postoperative analgesia management is to provide effective analgesia by using multimodal techniques, thus reducing opioid consumption and related complications, providing early mobilization and shorter hospital stay, and increasing patient comfort.

Once the effectiveness of the Erector Spinae Plane Block has been demonstrated in patients undergoing robotic colorectal surgery, it will be implemented routinely in our clinic, aiming to reduce postoperative narcotic analgesic consumption, protect patients from narcotic analgesic side effects, facilitate early patient mobilization, shorten hospital stays, and increase patient comfort.

Because no additional procedures or medications were administered to patients outside of routine procedures, no additional risks are anticipated.

Pain is a subjective symptom, and to minimize interpatient variability, it will be assessed using the Numeric Rating Scale (NRS), a standardized scale.

The Postoperative Nausea Vomiting Impact Scale Score will be used to assess postoperative nausea and vomiting.

All volunteers participating in the study, whether or not a block is applied, will receive intravenous analgesia postoperatively using patient-controlled analgesia devices containing 4 mg/ml tramadol, with no basal infusion, a lockout time of 30 minutes, a bolus dose of 3 ml, and no baseline infusion. Data on the time of patients' first analgesic needs, the total number of analgesic requests and at what time, and the total tramadol dose administered will be obtained and recorded from the PCA devices.

Inclusion Criteria:

• ASA I-III
• Male and female gender
• Ages 18-75
• Malignant patients undergoing robotic colorectal surgery

Exclusion Criteria:

• ASA>III
• Coagulopathy
• Morbid obesity
• History of chronic analgesic use
• Data loss due to limited cooperation during NRS follow-up

De-identifying, formatting and transferring data into a standardized, usable electronic format can be time-consuming.

The block was performed with the patients' consent. The control group did not receive the block. Therefore, due to the nature of the procedure, the patients were not blinded.

The block operator was not blinded.

The primary investigator assessing the patient outcomes did not know which patients received the block and which did not.