ESPB was administered preoperatively under ultrasound guidance via a high-frequency linear probe (Sonosite M-Turbo, Fujifilm Sonosite Inc., USA) (Figure 1). The procedure was as follows:

1. Patient Positioning: The patient was positioned in the lateral decubitus position, with the side to be blocked uppermost.
2. Ultrasound Setup: A high-frequency linear ultrasound probe was placed in a parasagittal orientation over the transverse process of the lumbar vertebra at the level of surgery.
3. Needle Insertion: After skin disinfection with chlorhexidine, a 22-gauge, 100-mm needle (Stimuplex A, B. Braun Melsungen AG, Germany) was inserted in-plane to the ultrasound probe. The needle was advanced until the tip contacted the transverse process.
4. Injection: Following negative aspiration to ensure no vascular puncture, 20 mL of 0.5% bupivacaine was injected incrementally, with real-time ultrasound visualization to confirm the correct spread of the anesthetic solution.

Wound infiltration was performed by the surgeon at the end of the surgery via the following procedure:

1. Preparation: After hemostasis was achieved and before skin closure, 20 mL of 0.5% bupivacaine was prepared in a sterile syringe.
2. For infiltration, the anesthetic mixture was infiltrated into multiple layers of the surgical wound. This included the subcutaneous tissue and muscle layers, ensuring the even distribution of the anesthetic solution to cover the entire surgical area.

ESPB was administered preoperatively under ultrasound guidance via a high-frequency linear probe (Sonosite M-Turbo, Fujifilm Sonosite Inc., USA) (Figure 1). The procedure was as follows:

1. Patient Positioning: The patient was positioned in the lateral decubitus position, with the side to be blocked uppermost.
2. Ultrasound Setup: A high-frequency linear ultrasound probe was placed in a parasagittal orientation over the transverse process of the lumbar vertebra at the level of surgery.
3. Needle Insertion: After skin disinfection with chlorhexidine, a 22-gauge, 100-mm needle (Stimuplex A, B. Braun Melsungen AG, Germany) was inserted in-plane to the ultrasound probe. The needle was advanced until the tip contacted the transverse process.
4. Injection: Following negative aspiration to ensure no vascular puncture, 20 mL of 0.5% bupivacaine was injected incrementally, with real-time ultrasound visualization to confirm the correct spread of the anesthetic solution.

The pain intensity was assessed via the visual analog scale (VAS).The VAS is a 10 cm scale ranging from 0 (no pain) to 10 (worst imaginable pain).

Recorded as morphine equivalents

Noted in hours postoperatively