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

Overview

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.

Adult patients scheduled for elective unilateral open inguinal hernia repair under spinal anesthesia will be enrolled. After written informed consent, eligible patients will be randomly assigned in a 1:1 ratio to one of two groups. In the intrathecal morphine group, patients will receive spinal anesthesia with 15 mg of 0.5% hyperbaric bupivacaine plus 100 mcg intrathecal morphine. No TFP block will be performed in this group. In the TFP block group, patients will receive spinal anesthesia with 15 mg of 0.5% hyperbaric bupivacaine without intrathecal morphine. In addition, an ultrasound-guided unilateral TFP block will be performed on the surgical side before surgery using 30 mL of 0.25% bupivacaine, within the maximum safe dose limits. All patients will receive a standardized multimodal postoperative analgesia protocol. Pain scores, rescue analgesic consumption, opioid-related adverse effects, quality of recovery, and safety outcomes will be recorded during the first 24 postoperative hours. Persistent or chronic postoperative inguinal pain may be evaluated exploratorily during follow-up if sufficient data are available.