External Oblique Intercostal Block vs Erector Spinae Plane Block for Postoperative Analgesia After Laparoscopic Cholecystectomy

Ultrasound-Guided External Oblique Intercostal Block Versus Erector Spinae Plane Block for Postoperative Analgesia After Laparoscopic Cholecystectomy: A Randomized Controlled Study

This randomized controlled study aims to compare the effects of the external oblique intercostal block (EOIB) and the erector spinae plane block (ESPB) on postoperative analgesia in adult patients undergoing elective laparoscopic cholecystectomy. Both EOIB and ESPB are ultrasound-guided regional anesthesia techniques currently used in clinical practice to improve postoperative pain control as part of multimodal analgesia strategies.

Laparoscopic cholecystectomy is a common minimally invasive surgical procedure; however, patients may still experience postoperative pain that can increase opioid consumption and delay recovery. Identifying the most effective regional anesthesia technique may improve postoperative analgesia and patient recovery.

In this study, eligible patients will be randomly assigned to receive either bilateral EOIB or bilateral ESPB in addition to standardized general anesthesia and postoperative patient-controlled analgesia. Postoperative pain scores, opioid consumption, quality of recovery, postoperative nausea and vomiting, and block-related complications will be evaluated during the first 24 hours after surgery. The study aims to provide comparative clinical evidence regarding the analgesic effectiveness of these two regional anesthesia techniques.

Study Overview

• Status: Completed
• Conditions: Pain Management; Erector Spina Plan Block; External Oblique Intercostal Block
• Intervention / Treatment: Procedure: Ultrasound-Guided External Oblique Intercostal Block; Procedure: Ultrasound-Guided Erector Spinae Plane Block

Detailed Description

This study is designed as a multicenter, prospective, randomized controlled trial aiming to evaluate and compare the postoperative analgesic outcomes of two ultrasound-guided regional anesthesia techniques, external oblique intercostal block (EOIB) and erector spinae plane block (ESPB), in adult patients undergoing elective laparoscopic cholecystectomy.EOIB and ESPB are ultrasound-guided regional anesthesia techniques that have been described for postoperative analgesia in upper abdominal surgery. In this study, the regional analgesic technique to be administered will be determined by randomization, while all other aspects of perioperative care will follow standard institutional practice. Except for the randomized allocation of the regional block technique, the research team will not alter routine anesthetic management.

The primary objective of the study is to compare cumulative intravenous morphine consumption during the first 24 hours after surgery between patients receiving EOIB and those receiving ESPB. Secondary objectives include assessment of postoperative pain scores at rest and during movement, quality of recovery, postoperative nausea and vomiting (PONV), intraoperative opioid consumption, rescue analgesic requirements, block-related complications, and opioid-related adverse effects.

Clinical Routine and Analgesic Protocol

All patients will be managed according to the standard multimodal analgesia protocol routinely used in the general surgery operating rooms of the participating institutions. Preoperatively, standard ASA monitoring will be applied, intravenous access will be established, and perioperative fluid management will be provided according to institutional practice. Mild sedation will be administered using intravenous midazolam at a dose of 0.02 mg/kg. Supplemental oxygen will be delivered via nasal cannula during block performance.

General anesthesia will be induced and maintained using routinely applied anesthetic agents. Intraoperative opioid administration will be titrated according to hemodynamic parameters to maintain mean arterial pressure and heart rate within acceptable limits, and total intraoperative opioid consumption will be recorded.

Postoperatively, all patients will receive intravenous paracetamol and intravenous tramadol as part of routine analgesic care. Intravenous morphine patient-controlled analgesia (PCA) will be provided to all patients using standardized settings, including a 1 mg bolus dose, a 10-minute lockout interval, and a 4-hour limit of 20 mg. Rescue analgesia will consist of intravenous tramadol infusion when pain remains uncontrolled (NRS ≥4), followed by intravenous morphine if necessary, according to the predefined protocol.

Block Techniques (Performed as Part of Study Protocol)

EOIB Group:

Patients allocated to the EOIB group will receive bilateral ultrasound-guided external oblique intercostal block approximately 45 minutes before surgery. With the patient in the supine position, a high-frequency linear ultrasound probe will be placed longitudinally along the anterior midaxillary line. Using an in-plane approach, a block needle will be advanced into the fascial plane deep to the external oblique muscle. A total volume of 30 mL of 0.25% bupivacaine will be administered bilaterally. The block will be performed by experienced anesthesiologists.

ESPB Group:

Patients allocated to the ESPB group will receive bilateral ultrasound-guided erector spinae plane block approximately 45 minutes before surgery. With the patient in the sitting position, following skin disinfection and sterile preparation, a convex ultrasound probe will be placed in a sagittal orientation approximately 2-3 cm lateral to the T7 spinous process. Using an in-plane approach, the needle will be advanced into the fascial plane deep to the erector spinae muscle. A total volume of 30 mL of 0.25% bupivacaine will be administered bilaterally, with sonographic confirmation of cranial and caudal spread.

Postoperative Assessment

Postoperative pain will be assessed using the 11-point Numeric Rating Scale (NRS; 0-10) at rest and during movement (deep breathing or coughing) at 0, 3, 6, 12, 18, and 24 hours after surgery. PONV will be evaluated using a verbal descriptive scale, and antiemetic treatment will be administered as needed according to institutional protocols.

Quality of recovery and patient satisfaction will be assessed using the Turkish version of the Quality of Recovery-15 (QoR-15) questionnaire at 24 hours postoperatively. Intraoperative opioid consumption, time to first PCA demand, rescue analgesic requirements, block-related complications (including pneumothorax, hematoma, vascular puncture, epidural spread, intrathecal injection, and local anesthetic systemic toxicity), and opioid-related side effects such as nausea, sedation, and respiratory depression will be recorded.

Dermatomal sensory block distribution will be assessed using a pinprick test with a 27-gauge needle 30 minutes after block application.

All data will be collected by trained personnel blinded to group allocation. Due to the low-risk nature of the interventions and the short follow-up period, no independent data monitoring committee has been established.

• Study Type: Interventional
• Enrollment (Actual): 60
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Turkey (Türkiye)
  • Karabük, Turkey (Türkiye), 78200
    • Karabuk Training and Research Hospital, Department of Anesthesiology and Reanimation
  • Samsun, Turkey (Türkiye), 55200
    • Department of Anesthesiology and Reanimation, Samsun City Hospital

Participation Criteria

Eligibility Criteria

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

Description

Inclusion Criteria

• Age between 18 and 80 years
• Scheduled to undergo elective laparoscopic cholecystectomy
• Classified as American Society of Anesthesiologists (ASA) physical status I-III
• Ability to understand and operate a patient-controlled analgesia (PCA) device
• Provision of written informed consent

Exclusion Criteria

• History of chronic opioid use for more than four weeks prior to surgery
• Presence of pre-existing chronic pain conditions, such as migraine or fibromyalgia
• History of alcohol or substance abuse
• Known hypersensitivity or allergy to local anesthetics or opioids
• Presence of severe organ dysfunction, including clinically significant hepatic or renal disease
• Any contraindication to regional anesthesia
• Severe psychiatric disorders impairing patient cooperation or the ability to reliably assess pain (e.g., psychosis, dementia)
• Pregnancy or breastfeeding
• Presence of hematological disorders

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
Active Comparator: Group EOIB; Patients allocated to the EOIB group will be transferred to the regional anesthesia area and monitored approximately 45 minutes before surgery. With the patient in the supine position, bilateral ultrasound-guided external oblique intercostal block (EOIB) will be performed. A total volume of 60 mL of 0.25% bupivacaine (30 mL per side) will be injected. General anesthesia will then be administered according to standard practice. In the postoperative period, additional analgesia will be provided using intravenous morphine patient-controlled analgesia (PCA).	Procedure: Ultrasound-Guided External Oblique Intercostal Block; Bilateral ultrasound-guided external oblique intercostal block performed approximately 45 minutes before surgery. A total of 60 mL of 0.25% bupivacaine (30 mL per side) is injected into the fascial plane deep to the external oblique muscle.
Active Comparator: Group ESPB; Patients allocated to the ESPB group will be transferred to the regional anesthesia area and monitored approximately 45 minutes before surgery. With the patient in the supine position, bilateral ultrasound-guided erector spinae plane block (ESPB) will be performed. A total volume of 60 mL of 0.25% bupivacaine (30 mL per side) will be injected. General anesthesia will then be administered according to standard practice. In the postoperative period, additional analgesia will be provided using intravenous morphine patient-controlled analgesia (PCA).	Procedure: Ultrasound-Guided Erector Spinae Plane Block; Bilateral ultrasound-guided erector spinae plane block performed approximately 45 minutes before surgery. A total of 60 mL of 0.25% bupivacaine (30 mL per side) is injected into the fascial plane deep to the erector spinae muscle at the thoracic level under ultrasound guidance.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
24-hour cumulative opioid consumption	Total opioid consumption within the first 24 hours, including PCA-administered morphine and rescue analgesics converted to morphine milligram equivalents (MME).	postoperative day 1

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
12-hour cumulative opioid consumption	Total opioid consumption within the first 12 hours, including PCA-administered morphine and rescue analgesics converted to MME.	postoperative 12th hour
Time to first PCA analgesic demand	Time at which the first analgesic is requested	Postoperative day 1
Opioid-related adverse effects	Presence of itching, sedation, fatigue, or respiratory depression related to opioid use.	Postoperative day 7
Postoperative nausea and vomiting incidence (PONV)	The severity of postoperative nausea and vomiting (PONV) will be assessed using a descriptive verbal rating scale at 0, 3, 6, 12, 18 and 24 hours after extubation. If a score of 3 or more, ondansetron 4 mg IV will be administered and will repeat after 8 hours if required (The PONV scale is 0 = no nausea; 1 = slight nausea; 2 = moderate nausea; 3 = vomiting once; and 4 = vomiting more than once).	Postoperative day 1
Postoperative pain scores (NRS at rest)	Pain status at rest will be assessed by numeric rating scale (NRS) score at 0, 3, 6, 12, 18 and 24 hours after surgery. In addition, the time until the first analgesic requirement will be recorded. The NRS is an 11-point numeric scale that ranges from 0 to 10.	postoperative day 1
Postoperative pain scores (NRS during activity)	Pain status during activity will be assessed by numeric rating scale (NRS) score at 0, 3, 6, 12, 18 and 24 hours after surgery. In addition, the time until the first analgesic requirement will be recorded. The NRS is an 11-point numeric scale that ranges from 0 to 10.	postoperative day 1
Patient-reported quality of recovery (QoR-15 score)	Quality of recovery will be assessed using the validated 15-item Quality of Recovery questionnaire (QoR-15). Each item is scored on an 11-point numeric scale (0-10), resulting in a total score ranging from 0 to 150, with higher scores indicating better postoperative recovery.	postoperative day 1
Number of patients requiring rescue analgesia	The number of patients requiring rescue analgesia due to inadequate postoperative pain control (Numeric Rating Scale [NRS] ≥4) despite standard analgesic management	Postoperative day 1
Block-related complications	Incidence of complications such as bleeding, hematoma, or local anesthetic systemic toxicity (LAST)	Postoperative day 7

Collaborators and Investigators

• Sponsor: Karabuk University
• Investigators: Principal Investigator: Elif Sarikaya Ozel, M.D., Karabuk Training and Research Hospital, Department of Anesthesiology

Study record dates

Study Major Dates

• Study Start (Actual): January 1, 2026
• Primary Completion (Actual): April 1, 2026
• Study Completion (Actual): April 15, 2026

Study Registration Dates

• First Submitted: January 21, 2026
• First Submitted That Met QC Criteria: January 28, 2026
• First Posted (Actual): January 30, 2026

Study Record Updates

• Last Update Posted (Actual): May 15, 2026
• Last Update Submitted That Met QC Criteria: May 13, 2026
• Last Verified: May 1, 2026

More Information

Terms related to this study

• Keywords: Laparoscopic Cholecystectomy; Erector Spinae Plane Block; External Oblique Intercostal Block; Ultrasound-Guided Nerve Block
• Additional Relevant MeSH Terms: Neurologic Manifestations; Nervous System Diseases; Neurobehavioral Manifestations; Perceptual Disorders; Pathological Conditions, Signs and Symptoms; Signs and Symptoms; Agnosia
• Other Study ID Numbers: EOIBESP2026

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: Individual participant data (IPD) will not be shared outside the study team, as the dataset contains sensitive clinical information and data sharing was not included in the original informed consent. Data will be used solely for the purposes of the current study and related scientific publications, in accordance with institutional policies and ethical regulations.

Drug and device information, study documents

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