Laparoscopic cholecystectomy is considered the gold standard for the surgical treatment of benign gallbladder diseases; however, despite its minimally invasive nature, a significant proportion of patients experience substantial early postoperative pain, which impacts patient comfort and the duration of hospital stay. The current PROSPECT review and previous studies emphasize that this pain is multifactorial-comprising somatic, visceral, and phrenic nerve-mediated shoulder-tip components-and therefore advocate for an opioid-sparing multimodal analgesic approach. Within this framework, first-line recommendations include paracetamol, NSAIDs/COX-2 inhibitors, dexamethasone, and local anesthetic infiltration of the surgical site and/or intraperitoneal cavity, alongside appropriate regional blocks; opioids should be reserved solely for rescue analgesia.

Ultrasound-guided regional anesthesia blocks are increasingly utilized for acute visceral pain conditions, such as renal colic. The Erector Spinae Plane Block (ESPB) is an interfacial block performed in the thoracic paraspinal region, and it is hypothesized that its extensive spread may influence somatic and, to some extent, visceral pain pathways. Nevertheless, anatomical and clinical studies report inconsistent effects of ESPB on visceral pain, noting that local anesthetics may not consistently reach the paravertebral space, thereby leading to variable block efficacy.

Consequently, the Intertransverse Process Block (ITPB), which targets a plane anatomically closer to the paravertebral space, has been described in recent years as an alternative technique. ITPB is performed by injecting local anesthetic into the interfacial space adjacent to the retro-superior costotransverse ligament; it is reported to carry a low risk of complications as it does not require direct orientation toward the pleura or neuraxial structures. Clinical trials indicate that ITPB provides analgesic efficacy comparable to paravertebral blocks in both thoracic and abdominal surgeries and reduces opioid consumption. Furthermore, anatomical studies suggest that the probability of local anesthetic spread into the paravertebral space is higher with ITPB than with ESPB.

However, a randomized controlled trial comparing ESPB and ITPB in patients undergoing laparoscopic cholecystectomy is currently lacking in the literature. Therefore, the present study was designed to address this gap.

Inclusion Criteria:

• Undergoing elective laparoscopic cholecystectomy
• Body mass index (BMI) between 18 and 35 kg/m²
• American Society of Anesthesiologists (ASA) physical status score of I-III
• Ability to provide written and verbal informed consent

Exclusion Criteria:

• Coagulopathy or use of anticoagulant medications
• Infection at the injection site
• Allergy to local anesthetics
• Pregnancy or breastfeeding
• Chronic opioid use or analgesic dependence
• Severe cardiopulmonary disease or psychiatric disorders
• Previous regional block performed within the last 24 hours
• Patients requiring emergency surgery
• Cases converted from laparoscopic surgery to open surgery

Eligible patients will be allocated into two groups-the ITPB group and the ESPB group-in a 1:1 ratio. Randomization will be performed using a computer-generated algorithm with variable block sizes (4-8). The randomly generated codes will be maintained by non-study personnel and will remain inaccessible to the investigators. The randomization sequence will be placed in sequentially numbered, opaque, sealed envelopes by a staff member not involved in the study. Through this methodology, triple-blinding will be ensured: the patient, the outcome assessor, and the data analyst will remain blinded to the group allocation.