Abdominal surgery causes severe postoperative pain due to retraction of the abdominal wall and direct manipulation of visceral organs. It leads to delayed postoperative recovery, increased postoperative morbidity and mortality. Intrathecal morphine, epidural analgesia and patient-controlled intravenous analgesia are used in postoperative pain management of abdominal surgeries. Intrathecal morphine is frequently used in many centers because it provides effective pain control. However; morphine has undesirable effects such as urinary retention, postoperative nausea and vomiting, and respiratory depression. Modified thoracoabdominal nerves block through perichondrial approach is a technique defined by the modification of the thoracoabdominal nerves block through perichondrial approach, in which local anesthetics are delivered only to the underside of the perichondral surface. The primary implication of this study is to compare postoperative pain scores and opioid consumption in patients undergoing major abdominal surgery with intrathecal morphine or modified thoracoabdominal nerves block through perichondrial approach.

Inclusion Criteria:

• Patients over 18 years old
• Patients undergoing major abdominal surgery

Exclusion Criteria:

• Patients with solid organ dysfunction
• Patients who receive opioid or corticosteroid medication prior to surgery
• Patients with bleeding diathesis
• Patients with psychiatric disorders
• Patients who can not be contacted after surgery