Aim: Transversus abdominis plane (TAP) block has been shown to provide effective postoperative analgesia in open inguinal hernia surgeries. However, although there are studies reporting that the quadro-iliac plane block provides adequate analgesia in the lower abdomen, there is no study specifically investigating its use in open inguinal hernia repair cases. The aim of this study was to contribute to the literature by determining which method is more effective for postoperative analgesia after open inguinal hernia surgery and whether it reduces opioid-related complications.
Introduction Open inguinal hernia repair is a common surgical procedure that can be performed under general or regional anesthesia. Although considered minimally invasive, open inguinal hernia repair may cause moderate to severe postoperative pain and may even progress to chronic pain, which can be equally distressing. Incisional pain is the most important factor determining how soon patients can return to work after surgery. Postoperative chronic pain, with a reported incidence ranging % 10, is one of the major complications of surgical hernia repair . Severe pain may delay postoperative ambulation, reduce patient satisfaction, and contribute to the development of chronic pain; these conditions are also associated with increased pulmonary and cardiac complications. Moreover, inadequate pain control may prolong hospital stay.
Postoperative pain arises from multiple causes. In open inguinal hernia repair, the predominant pain experienced by patients is a combination of visceral and incisional pain. Postoperative pain is a common complication that may trigger a neuroendocrine stress response characterized by increased secretion of catabolic and immunosuppressive pituitary hormones and activation of the sympathetic nervous system . The use of regional anesthesia and analgesia as part of multimodal analgesia has been shown to reduce the neuroendocrine stress response associated with pain and surgical trauma. Therefore, pain management should be approached using multimodal analgesia.
To reduce postoperative pain following inguinal hernia repair, nonsteroidal anti-inflammatory drugs, paracetamol, opioids, local anesthetics, and various regional anesthesia techniques are commonly used. However, opioids may cause adverse effects such as postoperative nausea and vomiting, constipation, and respiratory depression. Multimodal analgesia techniques have been widely implemented in postoperative pain management . Truncal blocks-including the transversus abdominis plane block (TAPB), quadratus lumborum block (QLB), rectus sheath block, and hernia block-play an important role in multimodal analgesia.
The anterolateral abdominal wall consists of the rectus abdominis, external oblique, internal oblique, and transversus abdominis muscles. The transversus abdominis plane is an anatomical plane located between the internal oblique and transversus abdominis muscles and contains the thoracolumbar nerves (T6-L1). The anterior and lateral abdominal walls are innervated by the anterior rami of the T7-T12 and L1 thoracoabdominal nerves. Therefore, injection of local anesthetic into the transversus abdominis plane provides sensory blockade from T7 to L1. The TAP block can be used as part of the analgesic regimen in various abdominal surgeries, including appendectomy, hernia repair, laparotomy, laparoscopic procedures, cesarean section, abdominal hysterectomy, pyloromyotomy, major abdominal wall surgery, and colostomy formation . In previous studies, Okur, Avelina, and colleagues demonstrated that TAP block provides superior analgesia in patients undergoing open inguinal hernia repair.
The quadro-iliac plane block (QIPB), first described in 2024 by Tulgar et al. , is a novel block technique intended to provide lumbosacral, abdominal, and hip analgesia. The target point of the QIPB lies between the internal iliac crest and the posterior surface of the quadratus lumborum (QL) muscle. Its anatomical spread has been shown to involve the posterior and anterior surfaces of the QL muscle, the transversalis fascia, the ilioinguinal, iliohypogastric, subcostal, and genitofemoral nerves, as well as the lumbar plexus. In subsequent case series by Atıcı, Güngör, Turan, and colleagues , QIPB was reported to provide both upper and lower abdominal blockade, as well as lumbosacral and sensory block.
Materials and Methods:
This study was designed as a prospective, randomized, double-blind observational study.
Patients will be informed about the procedure to be performed and written informed consent will be obtained from all participants. Patients included in the study will be randomly assigned to either Group T (Transversus Abdominis Plane Block) or Group Q (Quadro-Iliac Plane Block) according to a computer-generated randomization table prepared by a researcher not involved in the study.
To ensure blinding, each participant will be assigned a random code, and these codes will be placed in sealed envelopes. The anesthesiologist in the operating room will select the appropriate sealed envelope from a file, indicating the block to be performed for each randomized patient.
Methods Patients will be informed about the procedure to be performed, and written informed consent will be obtained from all participants. Patients included in the study will be randomly assigned to Group T or Group Q according to a computer-generated randomization table prepared by a researcher not involved in the study. To ensure blinding, each participant will be assigned a random code, and these codes will be placed in sealed envelopes. The anesthesiologist in the operating room will select the corresponding sealed envelope indicating the block to be performed for each randomized patient. The patient, surgeon, and personnel responsible for postoperative pain assessment will be blinded to group allocation.
Patients will be taken to the operating room or block area for peripheral nerve block administration. Standard anesthesia monitoring (noninvasive arterial blood pressure, heart rate, electrocardiography, and pulse oximetry) will be applied to all patients. Intravenous access will be established using a 20G catheter. Premedication will consist of midazolam 0.07-0.15 mg/kg and fentanyl 0.5 µg/kg. Supplemental oxygen will be administered via face mask. All block procedures will be performed under standard sterile conditions.
Transversus Abdominis Plane (TAP) Block With the patient in the supine position, the needle insertion site will be sterilized with 10% povidone-iodine. A linear ultrasound probe will be covered in a sterile manner. A 22-25G, 50-100 mm peripheral nerve block needle will be used. The ultrasound probe will be placed at the level of the umbilicus along the midaxillary line. After identifying the three abdominal muscle layers, the fascial plane between the internal oblique and transversus abdominis muscles will be visualized. The needle will be advanced using the in-plane technique (medial-to-lateral or lateral-to-medial). A total of 30 mL of 0.25% bupivacaine will be injected into the fascial plane between the relevant muscle layers.
Quadro-Iliac Plane Block With the patient in the prone position, the needle insertion site will be sterilized with 10% povidone-iodine, and the linear ultrasound probe will be prepared in a sterile manner. The probe will be positioned to visualize the L3 spinous process at the midline. After slight lateral movement, the transverse process within the erector spinae muscle will be identified. When the probe is rotated sagittally and moved caudally, the iliac crest will be visualized. The erector spinae, quadratus lumborum, and psoas major muscles will be identified. The needle will be advanced in-plane from cranial to caudal. After hydrodissection with 2 mL of normal saline, 30 mL of 0.25% bupivacaine will be injected.
Following completion of the peripheral block, patients will be positioned sitting for spinal anesthesia. The L4-L5 intervertebral space will be identified using anatomical landmarks, and the insertion site will be sterilized with 10% povidone-iodine. Under sterile conditions, a 25G spinal needle will be inserted into the subarachnoid space. After confirmation of clear cerebrospinal fluid flow, 12.5 mg of 0.5% hyperbaric bupivacaine will be administered intrathecally over one minute. Motor block will be assessed using the Bromage scale (0 = no paralysis; 1 = unable to raise extended leg; 2 = unable to flex knee; 3 = complete paralysis). Surgery will commence when Bromage score 3 is achieved and sensory block reaches the T10 dermatome level.
During open inguinal hernia repair, intraoperative hemodynamic parameters will be recorded. Patients with an Aldrete score \>9 will be transferred to the recovery room, where postoperative hemodynamic parameters will also be recorded.
Postoperative pain assessment will be performed by a ward nurse or anesthesiologist blinded to group allocation using the Numeric Rating Scale (NRS), a 0-10 scale (0 = no pain, 10 = worst imaginable pain). NRS scores at rest and during active movement (transition from supine to sitting position) will be recorded at 0, 1, 3, 6, 12, 18, and 24 hours postoperatively.
To determine the dermatomal level of sensory block, pinprick testing will be performed between T3 and L3 dermatomes at postoperative hours 2 and 24. The ilioinguinal and iliohypogastric nerves will be assessed 3-5 cm lateral to the midline and midaxillary line using a sterile needle. A three-point scale will be used (0 = no pain, 1 = decreased pain, 2 = normal pain), with scores of 0 or 1 considered effective. Sensation at the shoulder will serve as control.
For postoperative analgesia, all patients will receive intravenous paracetamol 1 g every 8 hours and intravenous tramadol via patient-controlled analgesia (PCA). The PCA protocol will consist of 10 mg tramadol bolus doses (maximum 300 mg/day), a 20-minute lockout interval, and no basal infusion. Tramadol consumption will be recorded at 0-1, 1-12, and 12-24 hours, as well as cumulatively over 24 hours.
Patients with NRS ≥4 will receive 25 µg intravenous fentanyl as rescue analgesia, and the number of administrations will be recorded. Time to first opioid requirement and total opioid consumption within the first 24 hours will be documented.
Postoperative nausea and vomiting (PONV) will be assessed using a four-point scale (1 = none; 2 = nausea only; 3 = single episode of vomiting or persistent nausea; 4 = ≥2 episodes of vomiting or severe retching). Patients with PONV score ≥2 will receive 4 mg intravenous ondansetron. Repeat doses will be administered at intervals of at least 4 hours if necessary. Total ondansetron consumption within 24 hours will be recorded.
Hemodynamic parameters (blood pressure and heart rate) will be recorded at 0, 1, 3, 6, 12, 18, and 24 hours postoperatively. The Quality of Recovery-15 (QoR-15) questionnaire will be administered twice: preoperatively in the waiting area on the morning of surgery and at 24 hours postoperatively. Patients will complete the Quality of Recovery-15 (QoR-15) questionnaire, a self-assessment survey that evaluates the quality of postoperative recovery in areas such as physical comfort, pain, independence, psychological support, and emotional state, both on the morning of surgery and 24 hours post-surgery. QoR-15 scores range from 0 to 150, with higher scores indicating better recovery quality. Demographic characteristics will be recorded preoperatively, and postoperative outcomes including time to first oral intake, time to first flatus/defecation, and time to first mobilization (unaided standing) will be documented.
