Comparison of Quadro-Iliac Plane Block and Transversalis Fascia Plane Block for Open Inguinal Hernia Repair

Inguinal hernia repair is one of the most commonly performed surgical procedures worldwide. Open inguinal hernia repair may be associated with moderate to severe postoperative pain, and inadequate acute pain control may adversely affect recovery and contribute to the development of chronic pain. The PROSPECT recommendations support the use of local and/or regional analgesic techniques as part of multimodal analgesia for open inguinal hernia repair. The sensory innervation of the inguinal region involves the subcostal, iliohypogastric, ilioinguinal, and genitofemoral nerves.

The transversalis fascia plane block (TFPB), described by Hebbard, is an interfascial plane block in which local anesthetic is injected into the plane between the transversus abdominis muscle and the transversalis fascia, targeting the T12-L1 region. The analgesic efficacy of TFPB for open inguinal hernia repair has been evaluated in randomized controlled studies.

The quadro-iliac plane block (QIPB) is a recently described interfascial plane block introduced by Tulgar et al. in 2024. In a cadaveric study, injectate spread to the ilioinguinal, iliohypogastric, subcostal, and genitofemoral nerves was reported. To our knowledge, no study has directly compared QIPB and TFPB for postoperative analgesia in patients undergoing open inguinal hernia repair.

This is a prospective observational cohort study to be conducted at Vezirköprü State Hospital between October 30, 2026, and February 28, 2027. The decision to perform QIPB or TFPB in patients included in the study will not be made according to the research protocol, and no randomization will be performed. The block technique to be applied will be determined independently of the patient's inclusion in the study, according to the routine clinical practice and clinical judgment of the attending anesthesiologist responsible for the patient. The investigators will not provide any guidance regarding the selection of the block technique. Patients receiving QIPB or TFPB as part of routine clinical practice will be prospectively followed and evaluated as two cohorts.

Following standard monitoring (electrocardiography, noninvasive blood pressure, and pulse oximetry), patients will be placed in the sitting position, and spinal anesthesia will be performed under aseptic conditions using a 25-G Quincke spinal needle via a midline approach at the L3-L4 or L4-L5 intervertebral space. After confirmation of free cerebrospinal fluid (CSF) flow, 13 mg of 0.5% hyperbaric bupivacaine and 15 μg of fentanyl will be administered intrathecally. For postoperative analgesia, 1 g of intravenous paracetamol and 50 mg of intravenous dexketoprofen will be administered.

At the end of surgery, block procedures will be performed under aseptic conditions and ultrasound guidance (Mindray) by anesthesiologists experienced in the respective block technique. For QIPB, the patient will be placed in the lateral decubitus position, and a convex ultrasound probe will be used to identify the quadratus lumborum muscle at its attachment to the iliac crest. The local anesthetic will be injected into the quadro-iliac plane between the posterior surface of the quadratus lumborum muscle and the inner surface of the iliac crest. TFPB will be performed with the patient in the supine position using a linear ultrasound probe, with the injection administered immediately beneath the fascia of the transversus abdominis muscle. An 80-mm Braun block needle will be used for both block procedures. As part of routine clinical practice, 40 mL of 0.25% bupivacaine will be used in patients receiving QIPB, whereas 30 mL of 0.25% bupivacaine will be used in patients receiving TFPB. Block performance time will be defined as the time from initial contact of the ultrasound probe with the patient until completion of the local anesthetic injection and will be recorded in seconds.

Postoperative analgesia will be continued in a standardized manner according to the institution's routine clinical practice. All patients will receive 1 g of intravenous paracetamol every 8 hours and 50 mg of intravenous dexketoprofen every 12 hours. When the NRS score is 4 or higher, intravenous tramadol at a dose of 1 mg/kg will be administered as rescue analgesia.

NRS scores will be recorded at rest and during coughing at 2, 4, 6, 12, and 24 hours postoperatively. The time to first rescue analgesic requirement, rescue tramadol use, block performance time, and adverse events including nausea, vomiting, hypotension, bradycardia, local anesthetic systemic toxicity, and other adverse events related to the block procedure will be monitored and recorded.