The present study demonstrated the analgesic efficacy of ESPB in patients who underwent LLDN for postoperative pain relief compared to local anesthetic wound infiltration. ESPB had significantly reduced the 24-hour cumulative morphine consumption and pain scores as measured by VNRS at all time points during the 24 h follow-up both at rest and during movement.

The management of postoperative pain is crucial for the early recovery of voluntary kidney donors. Pain following LLDN is multifactorial in origin [1]. Though the laparoscopic port site incisions are smaller than open surgeries and associated with shorter recovery time, the lower abdominal Pfannenstiel incision made to retrieve graft kidney causes significant pain and discomfort to the donors. Additionally, surgical dissection of abdominal and pelvic structures during the surgery lead to significant postoperative visceral pain which may require multimodal therapy for adequate analgesia [7]. Moreover, the fear of postoperative pain deters potential donors psychologically which could discourage them from donating organs.

ESPB has been used successfully in various thoraco-abdominal open and laparoscopic surgeries for intraoperative and postoperative pain management [8,9,10,11,12,13,14]. In ESPB, local anesthetic is injected into the fascial plane between the erector spinae muscle and vertebral transverse process [6]. This provides both visceral and somatic analgesia through direct blockade of dorsal, ventral ramus of the spinal nerve and sympathetic ganglion resulting from the spread of local anaesthetic to paravertebral space. Onay et al., in a small randomized controlled trial found ESPB resulted in similar postoperative pain scores and morphine consumption during the postoperative period compared to ultrasound-guided quadratus lumborum block for open nephrectomy surgery [15]. ESPB given at T9 level provided effective intraoperative and postoperative effective pain relief in patients who underwent retroperitoneal laparoscopic nephrectomy surgeries [16].

In 2023, Fan et al. in their randomized controlled trial conducted in 61 patients found that ESPB provided non-inferior analgesia in patients who underwent laparoscopic nephrectomy surgery compared to thoracic paravertebral block [17]. In another randomized controlled trial in 186 patients who underwent laparoscopic nephro-ureterectomy, Xu et al. reported the median (IQR) 24 h cumulative sufentanyl equivalent dose was 15 (5–30) microgram and the median (IQR) time to first patient controlled analgesia demand was 7 (4–18) hours in the ESPB group [18]. In our study, ESPB was administered after surgery but before extubation to prevent any unexpected hemodynamic instability that could potentially affect the outcome of the graft.

Very recently, Özlem Özkalayci et al., in a randomized controlled trial, in 52 patients who underwent, hand assisted-laparoscopic living donor nephrectomy, reported no significant difference in the intravenous morphine equivalent consumption (ESPB group 33.3 ± 21.4 mg vs. no block group 37.5 ± 18.5 mg; P = 0.27). They administered pre-induction, ultrasound ESPB block on the side of nephrectomy with 30 ml of Bupivacaine 0.25%. Based on a preliminary study Özlem Özkalayci et al., ESPB administered at T8/10 did not produce adequate analgesia in the lower abdomen where the hand port was placed hence, they decided to give the block at T12 level in the study. And they concluded that, augmenting the block intensity using bi-level or bilateral block techniques covering all-surgical sites. In our study, ESPB was administered after surgery but before extubation to prevent any unexpected hemodynamic instability that could potentially affect the outcome of the graft.

LLDN with Pfannenstiel incision to retrieve graft kidney is a common practice in our center. Since the Pfannenstiel incision (10–12 cm) crosses the midline, we gave bilateral block, with reduced volume on the dependent side. We did not come across any complications during the block procedure and in the postoperative period.

Our study has potential limitations that should be noted. Firstly, we could not use patient-controlled analgesia due to resource limitations. Secondly, preoperative anxiety and depression were not measured in our study which can affect pain perception and pain scores, although all potential donors underwent preoperative screening for any major psychological concerns related to organ donation. Thirdly, we did not evaluate the extent of dermatomal sensory block following the procedure. Fourthly, the dose of local anesthetic used in wound infiltration is lower than that used in ESPB. However, the rate of local anesthetic absorption from these sites may not be the same, and the NRS difference between the groups cannot be attributed to the dose difference alone. Further investigation is needed to determine the optimal injection level and volume required to provide analgesia for the Pfannenstiel incision on the opposite side of the surgery.