This study assesses the analgesic efficacy of ESPB during PTBD compared to fentanyl-based standard procedural analgesia. PTBD is a preferred intervention for biliary obstructions when ERCP or surgery is unfeasible. The procedure induces both somatic and visceral pain due to trauma to soft tissues, liver capsule stretching, and bile leakage, which may affect procedural success and patient comfort [10]. These pain sensations are often perceived as referred pain in the epigastric and hypochondriac regions. The pain experienced by the patient during and after the procedure negatively affects both patient and operator comfort, potentially impacting procedural success and duration.

Enhanced Recovery After Surgery (ERAS) protocols favor multimodal analgesia to minimize opioid-related adverse effects, including respiratory depression, gastrointestinal dysfunction, nausea, and dependence, which can delay recovery and prolong hospitalization [11]. ESPB provides both somatic and visceral analgesia while reducing opioid requirements and associated complications [12,13,14].

Various analgesic techniques have been used during PTBD, including IV sedation, epidural, paravertebral, interpleural, and transversus abdominis plane (TAP) blocks, each with benefits and limitations [13, 15, 16]. Recently, hepatic hilar nerve block has also been proposed as an effective method for pain control, especially during procedures such as radiofrequency ablation of liver lesions [17]. Although its use in PTBD is not yet well established, it may represent a promising alternative for selected patients. While remifentanil and intrathecal morphine can be effective, they increase postoperative nausea and opioid use [18]. Epidural analgesia remains an established and highly effective technique for managing postoperative pain in major open abdominal surgery, particularly due to its well-documented benefits in visceral pain control, opioid-sparing effects, and enhanced recovery. However, its use should be carefully balanced against patient-specific risks and the objectives of enhanced recovery protocols, as factors such as hypotension and coagulopathy may limit its applicability in certain patient populations [14, 19,20,21]. Harshfield et al. found that epidural anesthesia provided effective intraoperative pain control in 91% of patients but carried a 1% hypotension risk, while IV sedation resulted in inadequate pain relief in 50% of cases [22].

Culp et al. demonstrated that fluoroscopy-guided paravertebral block (PVB) significantly reduced pain and opioid use during PTBD [23]. However, PVB remains technically challenging due to its proximity to deeper structures, which increases the risk of serious complications such as pneumothorax, vascular injury, and intrathecal spread [24, 25]. In contrast, ESPB is easier to administer and has a lower complication profile.

Interpleural block (IPB) has shown variable efficacy, with a 52% success rate and an 18% failure rate in PTBD patients [26]. Given its 2–6% pneumothorax risk, ESPB may offer a safer alternative.

The PROSPECT guidelines recommend TAP blocks, epidural analgesia, and NSAIDs for hepatobiliary interventions but do not provide specific recommendations regarding ESPB [19]. While our study did not record cumulative opioid doses, the absence of high NRS scores and lack of additional opioid requirements in the ESPB group suggest a potential benefit in this context. These preliminary findings may help inform future investigations into the role of ESPB in percutaneous biliary procedures.

In a case report by Bharati et al., ultrasound-guided oblique subcostal transversus abdominis plane (OSTAP) block was described as a modification of TAP block and an effective analgesic method during PTBD [27]. But the generalizability of this technique remains limited due to the lack of larger studies. Additionally, our study supports the potential role of ESPB in reducing opioid requirements during PTBD, which may reflect its contribution to visceral pain modulation alongside somatic analgesia [28, 29].

Studies on hepatobiliary pain management primarily focus on surgical patients [30]. While Mutlu et al. demonstrated ESPB’s efficacy in cholecystostomy, no prior research has evaluated its role in interventional radiology [9]. Considering the risks such as hypotension and pneumothorax reported in the literature with techniques like epidural, PVB, IPB, and TAP block, the absence of such complications in patients who received ESPB in our study suggests that ESPB may offer a safer profile.

Our study suggests that ESPB may contribute to improved pain control in the early post-procedural period compared to PAF, as reflected by lower pain scores at 1 and 6 h post-PTBD. While ESPB’s anatomical spread is thought to provide both somatic and potential visceral analgesia, the exact onset dynamicsof pain relief were not specifically evaluated in this study. This study has several limitations that should be considered. Its retrospective, single-center design limits the generalizability of the findings. ESPB was predominantly utilized in patients considered at higher risk, such as those with organ dysfunction or who were unsuitable for sedation, introducing potential selection bias. Pain assessment relied on subjective patient-reported NRS scores, which may be influenced by individual perception and peri-procedural factors, and was limited to five time points within the first 12 h, without long-term follow-up. Furthermore, the procedures were performed by a limited number of operators, potentially introducing operator-dependent variability.

Additionally, specific procedural parameters such as the number of puncture attempts required for biliary access and total procedure duration were not systematically analyzed. Therefore, potential differences in technical complexity between groups could not be fully assessed, representing another important limitation.

Moreover, subgroup analyses were not performed to evaluate the potential influence of patient-related factors such as gender, age, or general frailty on pain scores. These variables may have affected pain perception and outcomes, but were not specifically assessed in this study.

Future multicenter, randomized controlled trials are warranted to validate these findings and to further evaluate the role of ESPB in PTBD analgesia across broader patient populations and in combination with other techniques.

In conclusion, ESPB appears to provide superior postoperative pain control over fentanyl-based analgesia in PTBD with pain relief after procedure. Given its ease of administration and opioid-sparing benefits, ESPB represents a promising alternative, particularly for high-risk patients. Further randomized controlled trials are needed to refine its role in PTBD.