Transversalis Fascia Plane Block Versus Low-Dose Intrathecal Morphine for Open Inguinal Hernia Repair

Open inguinal hernia repair is commonly associated with early postoperative pain, which may delay mobilization, reduce patient satisfaction, and increase opioid consumption. Low-dose intrathecal morphine may provide prolonged postoperative analgesia after spinal anesthesia; however, it may also be associated with opioid-related adverse effects such as nausea, vomiting, pruritus, urinary retention, sedation, and respiratory depression. The transversalis fascia plane block is an ultrasound-guided fascial plane block that targets the sensory innervation of the lower abdominal wall, particularly the T12-L1 dermatomal region and the ilioinguinal and iliohypogastric nerve distribution. Although TFP block has been evaluated in lower abdominal procedures, direct comparison with low-dose intrathecal morphine in open inguinal hernia repair is limited. This prospective, randomized, controlled, assessor-blinded trial aims to compare ultrasound-guided TFP block with low-dose intrathecal morphine in adult patients undergoing elective unilateral open inguinal hernia repair under spinal anesthesia. The primary outcome is total rescue opioid consumption during the first 24 postoperative hours. Secondary outcomes include pain scores at rest and with movement, time to first rescue analgesia, opioid-related adverse effects, quality of recovery, patient satisfaction, mobilization time, readiness for discharge, block success, sensory block distribution, and block-related complications.

Inclusion Criteria: * Adult patients aged 18-80 years * Patients scheduled for elective unilateral open inguinal hernia repair * ASA physical status I-III * Patients planned to undergo spinal anesthesia * Patients able to understand and report postoperative pain scores * Patients who provide written informed consent Exclusion Criteria: * Refusal to participate * Bilateral inguinal hernia repair * Recurrent inguinal hernia repair * Emergency, incarcerated, or strangulated hernia * Need for general anesthesia * Contraindication to spinal anesthesia * Coagulopathy or anticoagulant use contraindicating neuraxial or peripheral block * Infection at the injection site * Known allergy to local anesthetics, morphine, or study medications * Chronic opioid use * Preoperative chronic groin pain or neuropathic pain history * Severe hepatic or renal failure * Neurological or psychiatric condition preventing communication or pain assessment * Expected inability to complete postoperative follow-up