The Effect of Different Volumes of Ilioinguinal-Iliohypogastric Nerve Block on Postoperative Analgesia in Inguinal Hernia Surgery

The primary objective of this study is to evaluate and compare the efficacy of different volumes of local anesthetics, administered at the same total dose, for ilioinguinal and iliohypogastric (II/IH) nerve blocks in patients undergoing unilateral inguinal hernia repair.

The investigators aim to determine whether varying the injectate volume-while keeping the total drug amount constant-influences the quality and duration of postoperative analgesia. By monitoring pain scores and opioid consumption, this research seeks to identify the optimal volume-to-dose ratio for enhancing patient recovery and pain management following inguinal surgery.

Study Overview

• Status: Not yet recruiting
• Conditions: Inguinal Hernia Postoperative Pain Acute Pain
• Intervention / Treatment: Drug: Bupivacaine (Ilioinguinal-iliohypogastric nerve block)

Detailed Description

Study Design and Patient Selection This study is designed as a prospective, randomized, controlled, single-center trial to evaluate the efficacy of different local anesthetic volumes in ilioinguinal-iliohypogastric (II-IH) nerve blocks. The study is conducted in accordance with the Declaration of Helsinki. Patients aged 18-75, with an ASA physical status of I-III, scheduled for unilateral open inguinal hernia repair under spinal anesthesia, are eligible for inclusion. Exclusion criteria include BMI >35 kg/m², pregnancy, emergency surgery, coagulopathy, infection at the injection site, known allergy to local anesthetics, chronic opioid use, and cognitive impairment.

Randomization and Blinding A total of 70 patients are randomly assigned to two equal groups (1:1 ratio) using a computer-generated sequence and the sealed envelope method. The study is assessor-blinded; while the anesthesiologist performing the nerve block is aware of the group allocation, the researchers responsible for postoperative pain assessment and the statisticians are blinded to the group assignments.

Interventional Procedure All patients receive standard monitoring and minimal sedation with 1 mg of IV midazolam. The II-IH nerve block is performed under ultrasound guidance (high-frequency linear probe) 30 minutes before spinal anesthesia using an in-plane technique. The needle is positioned between the internal oblique and transversus abdominis muscles, and the position is confirmed via hydrodissection.

Group 1 (Low Volume): Receives 10 mL of 0.375% bupivacaine (7.5 mL of 0.5% bupivacaine + 2.5 mL of saline).

Group 2 (High Volume): Receives 20 mL of 0.1875% bupivacaine (7.5 mL of 0.5% bupivacaine + 12.5 mL of saline).

Sensory block success is confirmed via pin-prick and cold tests 20-30 minutes after the procedure. Spinal anesthesia is subsequently performed at the L3-L4 level using 15 mg of 0.5% hyperbaric bupivacaine.

Outcome Measures and Follow-up Following surgery, patients are monitored in the Post-Anesthesia Care Unit (PACU) and transferred to the ward once they meet standard discharge criteria (Bromage score ≤2, Aldrete score ≥9).

Primary Outcome: Time to first analgesic requirement, defined as the duration from the block administration until the patient reports a Visual Analog Scale (VAS) or Numerical Rating Scale (NRS) score of ≥4.

Secondary Outcomes: * Static and dynamic VAS/NRS scores at 0, 2, 6, 12, and 24 hours postoperatively.

Total 24-hour tramadol consumption (100 mg IV tramadol is administered as rescue analgesia for pain scores ≥4).

Incidence of postoperative complications (nausea, vomiting, urinary retention, hematoma, pruritus).

Time to first mobilization and patient/surgeon satisfaction.

Assessment of chronic postoperative pain at 3 and 6 months through outpatient follow-ups or telephone interviews.

Statistical Analysis Statistical analysis will be performed using SPSS version 26.0.

Descriptive data will be presented as mean, standard deviation, median, minimum, maximum, frequency, and percentage.

Normality will be assessed using skewness and kurtosis.

Between-group comparisons will be performed using independent samples t-test or Mann-Whitney U test.

Repeated measures ANOVA with Bonferroni post hoc test will be used for within-group comparisons over time.

Categorical variables will be analyzed using Chi-square test.

A p-value ≤ 0.05 will be considered statistically significant.

• Study Type: Interventional
• Enrollment (Estimated): 70
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Berivan Bedir Sert, Medical doctor; Phone Number: +905530884221; Email: berivan34113@hotmail.com

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Patients aged between 18 and 75 years
• American Society of Anesthesiologists (ASA) physical status I, II, or III
• Diagnosis of unilateral inguinal hernia
• Scheduled for elective open inguinal hernia repair under spinal anesthesia

Exclusion Criteria:

• Age under 18 or over 75 years
• ASA physical status IV or higher
• Body mass index (BMI) greater than 35 kg/m²
• Pregnancy or suspected pregnancy
• Emergency surgery
• Refusal to provide informed consent
• Known or suspected coagulopathy
• Local infection at the site of the nerve block
• Known allergy to local anesthetics
• History of chronic opioid use or substance abuse
• Cognitive impairment or inability to cooperate with study procedures (e.g., inability to use the visual analog scale)

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Double

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Grup I: Low Volume Group(10 mL); Patients in this group will receive a 10 mL volume of 0.375% bupivacaine(37.5 mg) for the ultrasound-guided ilioinguinal-iliohypogastric block.	Drug: Bupivacaine (Ilioinguinal-iliohypogastric nerve block); "Participants are randomized into two intervention groups to receive ultrasound-guided ilioinguinal-iliohypogastric nerve blocks with a fixed total dose of 37.5 mg bupivacaine. Group 1 (Low Volume): Receives 10 mL of 0.375% bupivacaine. Group 2 (High Volume): Receives 20 mL of 0.1875% bupivacaine. The procedure is performed using a high-frequency linear ultrasound probe. After the identification of the ilioinguinal and iliohypogastric nerves between the internal oblique and transversus abdominis muscles, the specified volume of local anesthetic is injected. All patients undergo the same surgical procedure (unilateral inguinal hernia repair) under spinal anesthesia. The primary focus is to evaluate the impact of local anesthetic volume on the duration and quality of postoperative analgesia."
Experimental: Grup II: Hıgh Volume Group(20 mL); Patients in this group will receive a 20 mL volume of 0.1875% bupivacaine(37.5 mg) for the ultrasound-guided ilioinguinal-iliohypogastric block.	Drug: Bupivacaine (Ilioinguinal-iliohypogastric nerve block); "Participants are randomized into two intervention groups to receive ultrasound-guided ilioinguinal-iliohypogastric nerve blocks with a fixed total dose of 37.5 mg bupivacaine. Group 1 (Low Volume): Receives 10 mL of 0.375% bupivacaine. Group 2 (High Volume): Receives 20 mL of 0.1875% bupivacaine. The procedure is performed using a high-frequency linear ultrasound probe. After the identification of the ilioinguinal and iliohypogastric nerves between the internal oblique and transversus abdominis muscles, the specified volume of local anesthetic is injected. All patients undergo the same surgical procedure (unilateral inguinal hernia repair) under spinal anesthesia. The primary focus is to evaluate the impact of local anesthetic volume on the duration and quality of postoperative analgesia."

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Time to first rescue analgesic requirement.	The time elapsed (measured in hours) from the completion of the ilioinguinal-iliohypogastric nerve block until the patient first requests or requires supplemental (rescue) analgesic medication due to a Visual Analog Scale (VAS) score of $\ge 4$. This reflects the effective duration of the sensory block provided by the local anesthetic.	Up to 24 hours postoperatively.

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Postoperative Pain Intensity	Pain intensity will be assessed using the Visual Analog Scale (VAS) at rest and during movement. The scale ranges from 0 (no pain) to 10 (the worst imaginable pain)	Up to 24 hours postoperatively
Total Analgesic Consumption	The total cumulative dose of supplemental rescue analgesic medication (such as paracetamol or tramadol) consumed by the patient, measured in milligrams. This measures the opioid-spar	Up to 24 hours postoperatively.

Collaborators and Investigators

• Sponsor: Saglik Bilimleri Universitesi Gazi Yasargil Training and Research Hospital

Study record dates

Study Major Dates

• Study Start (Estimated): April 14, 2026
• Primary Completion (Estimated): May 14, 2026
• Study Completion (Estimated): November 14, 2026

Study Registration Dates

• First Submitted: April 29, 2026
• First Submitted That Met QC Criteria: May 6, 2026
• First Posted (Actual): May 12, 2026

Study Record Updates

• Last Update Posted (Actual): May 12, 2026
• Last Update Submitted That Met QC Criteria: May 6, 2026
• Last Verified: May 1, 2026

More Information

Terms related to this study

• Keywords: Unilateral inguinal hernia Ilioinguinal-iliohypogastric nerve block Postoperative analgesia Local anesthetic volume
• Additional Relevant MeSH Terms: Organic Chemicals; Anilides; Amides; Aniline Compounds; Amines; Bupivacaine
• Other Study ID Numbers: SBUGaziYasargilTRH2026

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: "Individual participant data will not be shared to protect patient confidentiality and ensure compliance with local data protection regulations. The study protocols and results will be made available through publication, but the raw data set is restricted to the primary investigators to maintain the integrity of the institutional data policy."

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No