Efficacy of ultrasound-guided sacral erector spinae block in elective surgery. An up-to-date systematic review and meta-analysis of randomised controlled trials

Abstract

Background and Aims:

The sacral erector spinae plane block (SESPB) is emerging as a promising ultrasound-guided regional anaesthesia technique for postoperative pain management in various surgical procedures. This systematic review and meta-analysis aimed to investigate the efficacy of SESPB when used in combination with spinal anaesthesia.

Methods:

We conducted a search of PubMed/MEDLINE, EMBASE, ClinicalTrials.gov and the Cochrane Central Register of Controlled Trials, covering literature up to April 2025. Our analysis included randomised controlled trials (RCTs) that compared the outcomes of SESPB used with spinal anaesthesia against spinal anaesthesia alone in patients undergoing elective surgeries. The primary endpoint was the need for rescue opioid analgesics in the postoperative period. Secondary outcomes included postoperative pain levels at 12 and 24 h after surgery, the total amount of opioids consumed in the postoperative period and the time to the first opioid requirement after surgery.

Results:

We identified and included three RCTs in the quantitative analysis. The pooled data indicated that SESPB combined with spinal anaesthesia significantly reduced the need for rescue opioid analgesics compared with spinal anaesthesia alone (odds ratio = 0.05; 95% confidence interval = 0.02,0.16; P < 0.00001; I² = 14%). Additionally, the use of SESPB was associated with improved postoperative pain management at 24 h, although it did not yield a statistically significant reduction in the total amount of opioid consumed in the postoperative period and the timing of rescue opioid administration.

Conclusions:

This meta-analysis of RCTs indicated that the use of SESPB in conjunction with spinal anaesthesia results in a reduced need for rescue opioid analgesics and improved postoperative pain management at 24 h for patients undergoing elective surgery.

INTRODUCTION

Effective analgesia and pain management are key components of perioperative care for elective surgeries to improve patient outcomes.[1,2,3] Adequate pain control not only facilitates patients’ recovery but also minimises complications associated with poor pain management, such as excessive opioid consumption and prolonged hospital stays. Regional anaesthesia techniques play a pivotal role in postoperative pain management, with ultrasound-guided fascial plane blocks (FPBs) gaining prominence for their ability to provide targeted analgesia.[2] The early FPBs were guided by surface anatomical landmarks, with needle placement determined by the tactile “pop” sensation upon penetrating the fascial layers. However, ultrasound guidance, a significant advancement in the field, has largely replaced blind techniques with a method that ensures greater precision and accuracy, allowing real-time visualisation of anatomical structures and thereby enhancing both safety and efficacy. The primary objective of FPBs is to block nerves traversing the fascial planes.[4,5,6,7] The local anaesthetic can reach nerves that may be relatively distant from the initial administration site through a combination of pressure gradient-driven bulk flow and diffusion along a concentration gradient. Consequently, FPBs require a high volume of injectate and a considerable amount of time to achieve proper diffusion.[8] The ultrasound-guided sacral erector spinae plane block (SESPB), first introduced in 2019 by Tulgar for analgesia in pilonidal sinus surgery, involves the deposition of local anaesthetic in the dense interfascial plane beneath the multifidus muscle or its aponeurosis at the intermediate or median sacral crest.[9] The mechanism of action of the SESPB likely involves blocking the dorsal roots of sacral nerves emerging from the sacral foramina and the potential cephalad spread of the injectate.[10] Anatomical studies have shown that the injectate can spread from this superficial posterior area, where there is minimal risk of bleeding or nerve injury, toward the sacral and lumbar nerve roots in a cephalad and anterior direction.[11,12] The versatility of the SESPB has led to its adoption across a wide range of surgical fields, including reconstructive sacral surgery,[13] paediatric urological surgery,[14] perineal surgery,[15] gender reassignment procedures,[16] and, more recently, orthopaedics.[17,18,19]

Despite the growing interest in the SESPB, randomised controlled trials (RCTs) investigating its efficacy remain limited. This scarcity of high-quality evidence underscores the need for further research. In response to the increasing interest within the locoregional anaesthesia community in exploring novel fascial approaches, we conducted an updated systematic review and meta-analysis of available RCTs to evaluate the efficacy of the SESPB in combination with spinal anaesthesia for patients undergoing elective surgeries. This analysis aims to provide evidence-based insights into the potential of the SESPB to enhance postoperative pain control, reduce opioid consumption and improve other relevant clinical outcomes, thereby informing and influencing medical practice.

METHODS

This systematic review and meta-analysis were conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and Cochrane methodology.[20,21] The original protocol for this study is registered in the International Prospective Register of Systematic Reviews (PROSPERO ID: CRD42025636765).

We designed the review following the objective PICOS (Population, Intervention, Comparison, Outcome, Study design) framework: (1) Population: patients aged 18 years and or older undergoing elective surgeries, (2) Intervention: SESPB combined with central subarachnoid (spinal) locoregional anaesthesia, (3) Comparison: central subarachnoid (spinal) locoregional anaesthesia without nerve blocks, (4) Outcome: the primary and secondary outcomes listed below and (5) Study design: randomised controlled trials.

Search strategy and study selection

Two reviewers independently searched PubMed/MEDLINE, Embase, the Cochrane Central Register of Controlled Trials and ClinicalTrials.gov, without language restrictions, for relevant studies covering the period from inception to 5 April 2025. Studies were included based on agreement between the two reviewers, with disagreements resolved through discussion or, when necessary, consultation with a third author. The search strategy [Supplementary Table 1] sought to identify RCTs comparing the use of SESPB in combination with spinal anaesthesia to spinal anaesthesia alone in patients undergoing elective surgeries. We included (1) RCTs, (2) studies enroling hospitalised adults (aged ≥18 years, regardless of gender or ethnicity and (3) trials comparing SESPB in combination with spinal anaesthesia versus spinal anaesthesia without blocks. We excluded trials enroling paediatric patients and those involving nonparallel, nonrandomised, or quasi-randomised trial designs.

Supplementary Table 1.

Search strategies

PubMed   sacral erector spinae block AND (‘randomized controlled trial’[pt] OR ‘controlled clinical trial’[pt] OR randomized[tiab] OR placebo[tiab] OR ‘drug therapy’[sh] OR randomly[tiab] OR trial[tiab] OR groups[tiab])

Embase   (‘sacral erector spinae plane block’/exp OR ‘sacral erector spinae plane block’) AND randomized

Cochrane Central Register of Clinical Trials   sacral erector spinae block AND randomized

ClinicalTrials.gov   Using the keywords ‘randomized’ and ‘sacral erector spinae plane block’

Study outcomes

The primary outcome of this study was the need for rescue opioid analgesics in the postoperative period. Secondary outcomes included postoperative pain at 12 and 24 h after surgery, measured using the visual analogue scale (VAS) or the numerical rating scale (NRS); the total amount of opioid consumed in the postoperative period; and the time to the first opioid requirement after surgery.

Data abstraction and risk of bias assessment

For each identified trial, two reviewers independently abstracted data on the overall sample size, treatment type and dosage, control therapy and specified outcomes. Trial investigators were contacted by email for additional data if they were not available in the trial manuscript [Supplementary Table 2].

Supplementary Table 2.

Outcomes and comments on data extraction

Outcome	Comments
Primary Outcomes Need for rescue opioid analgesic in the postoperative period.
Secondary Outcomes* Postoperative pain 12 h after surgery	Missing data from RCT: -Behera S 2024[26]
Postoperative pain 24 h after surgery
Total amount of opioid consumed in the postoperative period
Time for the first opioid requirement after surgery	Missing data from RCT: -Mermer A 2023[28]

RCT=randomised controlled trial. * The authors of the RCTs were contacted by email to obtain missing data

Two independent reviewers assessed the risk of bias in the RCTs using the Cochrane risk-of-bias tool for randomised trials, version 2 (RoB 2), for the primary outcome.[22] Each study’s overall risk of bias was classified as “Low,” “Some concerns” or “High.” The presence of small-study effects and publication bias for the primary outcome was examined through visual inspection of a funnel plot and formally tested using Egger’s test with OnlineMeta.[23]

Data analysis

Analyses were conducted using RevMan 5.4.1 (Review Manager, The Nordic Cochrane Centre, The Cochrane Collaboration, Copenhagen, Denmark). Pooled odds ratios (ORs) and their 95% confidence intervals (95% CIs) were calculated for dichotomous outcomes using the Mantel–Haenszel method. In comparison, continuous outcomes were analysed using weighted mean differences (MD) and their 95% CIs with the inverse variance method. For pooled outcome analyses, a P value ≤0.05 was considered statistically significant. Results reported as medians and interquartile ranges were converted to means and standard deviations to standardise results across all studies, following Cochrane methodology.[21] Trial sequential analysis (TSA) was performed for the primary outcome.[24,25] A fixed-effects TSA was conducted to maintain an overall 5% risk of type I error and a 10% risk of type II error, at a power of 90%. A relative risk reduction of 40% was assumed, and the control event proportion was derived from the dataset. TSA was performed using TSA software (version 0.9.5.10 Beta; The Copenhagen Trial Unit, Centre for Clinical Intervention Research, The Capital Region, Copenhagen University Hospital – Rigshospitalet, 2021).

Heterogeneity analysis

Heterogeneity was initially evaluated through visual inspection of the forest plots and then formally assessed using the I² statistic. RevMan 5.4.1 (Review Manager, The Nordic Cochrane Centre, The Cochrane Collaboration, Copenhagen, Denmark) was used to test the heterogeneity hypothesis. Statistical heterogeneity was considered low for I² ˂ 25%, moderate for 26%–50% and high for >50%. Fixed-effects models were applied in cases of low to moderate heterogeneity, whereas random-effects models were used for high heterogeneity.

RESULTS

Study characteristics

The search strategy identified potential studies in PubMed/MEDLINE (N = 12), Embase (N = 11), the Cochrane Central Register of Controlled Trials (N = 30) and ClinicalTrials.gov (N = 17). After removing duplicates and applying the eligibility criteria, three studies were included in the analysis, randomising a total of 180 patients.[26,27,28] [Figure 1].

Figure 1.

Preferred reporting items for systematic reviews and meta-analyses (PRISMA) flow diagram. RCT = randomised controlled trial; QLB = quadratus lumborum block; SESPB = sacral erector spinae plane block

In all RCTs, tramadol was the opioid medication used to manage postoperative pain. [Table 1].

Table 1.

Main characteristics of the included randomised controlled trials

RCT	SESPB	LA	Needle	Ultrasound Probe	Central locoregional anaesthesia (spinal)	N° patients treatment group	N° patients control group	Country	Enrolment period
Behera S 2024[26]	S1 intermediate	20 mL 0.2% ropivacaine + dexamethasone 4 mg	100 mm, 21 G	Linear, 6–13 MHz	saddle block, 1.2 mL of 0.5% bupivacaine heavy	30	30	India	1 April–26 December 2021
Satici M 2024[27]	S2 intermediate	20 mL: 10 mL 0.5% bupivacaine, 5 mL 2% lidocaine, 5 mL saline	100 mm, 22 G	Linear, 6–13 MHz	L3–L4/L4–L5 3 mL 0.5% bupivacaine	25	25	Turkey	January –April 2024
Mermer A 2023[28]	S2 intermediate	20 mL: 10 mL 0.5% bupivacaine, 5 mL 2% lidocaine, 5 mL saline	///	Linear, 6–13 MHz	L3–L4/L4–L5 2.5 mL 0.5% bupivacaine	35	35	Turkey	1 June–7 July 2023

ESPB=sacral erector spinae plane block, N°=number, RCTs=randomised controlled trials, LA=local anaesthetic

Of the three included RCTs, one was considered as having a high overall risk of bias, another raised some concerns and the final one was classified as having a low risk of bias.[29] [See Figure 2]. Supplementary Figure 1 ^{(493.4KB, tif)} presents the funnel plot of the primary outcome.

Figure 2.

Traffic plot of randomised controlled trials included in the meta-analysis

Quantitative data synthesis

Figure 3 shows the forest plot of the rate of rescue opioid analgesic use according to the three included RCTs. The rate of rescue opioid analgesic use in patients who received SESPB combined with spinal anaesthesia was 26.7% (24/90), compared with 64.4% (58/90) in those treated with spinal anaesthesia alone (OR = 0.05; 95% CI = 0.02,0.16; P < 0.00001; I² = 14%; Egger’s test P = 0.46). The magnitude and direction of the effect size were consistent when each study was sequentially removed and the pooled estimates reassessed. The lowest OR was 0.03 (95% CI = 0.01,0.13; P < 0.00001; I² = 0%) after excluding Behera S, 2024, and the highest OR was 0.12 (95% CI = 0.02,0.69; P = 0.02; I² = 0%) after excluding Mermer A, 2023.

Figure 3.

Forest plot of the need for rescue opioid analgesics in the postoperative period. M-H = Mantel–Haenszel, CI = confidence interval, SESPB = sacral erector spinae plane block

The VAS/NRS score was lower in patients treated with SESPB combined with spinal anaesthesia compared with those receiving spinal anaesthesia without blocks at both 12 h (VAS/NRS score: MD = 1.49; 95% CI = −4.93,1.95; P = 0.40; I² = 94%; Supplementary Figure 2 ^{(266.3KB, tif)} ) and, with statistical significance, at 24 h after surgery (VAS/NRS score: MD = −0.87; 95% CI = −1.20,−0.54; P < 0.00001; I² = 66%; Figure 4a).

Figure 4.

a. Forest plot of postoperative pain 24 h after surgery (VAS/NRS score). b. Forest plot of the total amount of opioid consumed in the postoperative period (tramadol, mg). M-H = Mantel–Haenszel, CI = confidence interval, SESPB = sacral erector spinae plane block, IV = inverse variance, SD = standard deviation, VAS = visual analogue scale; NRS = numerical rating scale

The forest plot in Figure 4b shows that the total amount of opioid (tramadol, mg) consumed was nonsignificantly lower in patients treated with SESPB combined with spinal anaesthesia compared with those receiving spinal anaesthesia alone (MD = −97.24 mg; 95% CI = −203.61,9.13 mg; P = 0.07; I² = 99%). The time to the first opioid requirement after surgery was nonsignificantly longer in patients treated with SESPB combined with spinal anaesthesia compared to those receiving spinal anaesthesia without blocks (MD: 7.26 h; 95% CI = −5.04, 19.57] h; P = 0.25; I² = 88%; Supplementary Figure 3 ^{(281.8KB, tif)} ). The results of the primary outcome and all secondary outcomes are presented in Table 2. The TSA showed that the pooled sample size was approximately 90% of the estimated required information size, and the cumulative Z-curve crossed both the conventional boundary and the TSA boundary for benefit, confirming the results of the meta-analysis while highlighting the need for further research to validate these findings [Supplementary Figure 4 ^{(1.2MB, tif)} ].

Table 2.

Pooled analysis of studies comparing SESPB combined with spinal anaesthesia versus spinal anaesthesia alone

Outcomes	SESPB Group	Control Group	Measure of Association	P	I2 (%)
Primary Outcome	Events/patients (%)	Events/patients (%)	OR (95% CI)
Need for rescue opioid analgesics in the postoperative period	24/90 (26.7%)	58/90 (64.4%)	0.05 (0.02,0.16)	<0.00001	14%
Secondary Outcomes	N° patients	N° patients	MD (95% CI)
Postoperative pain 12 h after surgery (VAS/NRS score)	60	60	–1.49 VAS/NRS score ([−4.93],[1.95] VAS/NRS score)	0.40	94%
Postoperative pain 24 h after surgery (VAS/NRS score)	90	90	–0.87 VAS/NRS score ([−1.20], [−0.54] VAS/NRS score)	<0.00001	66%
Total amount of opioid consumed in the postoperative period (tramadol mg)	90	90	–97.24 mg ([−203.61],[9.13] mg)	0.07	99%
Time for the first opioid requirement after surgery (hours)	55	55	7.26 hours ([−5.04],[19.57] h)	0.25	88%

OR=odds ratio, MD=mean difference, CI=confidence interval, VAS=visual analogue scale, NRS=numeric rating scale

DISCUSSION

Our systematic review and meta-analysis demonstrate that the use of SESPB in combination with spinal anaesthesia significantly reduces the need for rescue opioid analgesic administration in the postoperative period for patients undergoing elective surgeries compared to spinal anaesthesia alone. Although the reductions in total opioid consumption and the prolongation of effective analgesia were not statistically significant, these findings are encouraging and suggest that SESPB warrants further investigation as an opioid-sparing strategy. Moreover, patients who received SESPB experienced improved postoperative pain control at 24 h after surgery.

Interest in the use of SESPB has increased in recent years, with trials assessing its effectiveness across various clinical settings. However, to our knowledge, no previous meta-analysis has evaluated evidence from RCTs on the use of SESPB in combination with spinal anaesthesia for adult patients undergoing elective surgery. Thus, this meta-analysis represents the first comprehensive synthesis of data from RCTs on this specific application of SESPB, addressing a notable gap in the existing literature. Several RCTs identified in the literature did not meet our inclusion criteria. For instance, some evaluated SESPB in paediatric populations[14] or in adults undergoing general anaesthesia.[19] By restricting our analysis to adult patients receiving SESPB in conjunction with spinal anaesthesia for elective surgeries, we have enhanced the specificity and clinical relevance of our findings. The results of our meta-analysis indicate that SESPB is associated with a reduction in the need for rescue opioid analgesics in the postoperative period, supporting its role as a valuable adjunct to neuraxial anaesthesia in elective surgeries. Opioid-sparing strategies are critical in contemporary anaesthesia due to the well-documented risks associated with opioid use, including postoperative nausea and vomiting, respiratory depression and other systemic side effects.[30] This analysis also highlights the potential of SESPB to reduce the use of nonopioid analgesics, offering an alternative pain management approach that minimises reliance on pharmacological interventions with notable side effects. For example, Behera S. et al. (2024)[26] reported a reduced need for rescue tramadol in patients who received SESPB, whereas the control group required nonsteroidal anti-inflammatory drugs (NSAIDs, diclofenac) more frequently. This finding is particularly relevant for populations with comorbidities such as nephropathy or advanced age, for whom NSAIDs use poses risks such as renal impairment and gastrointestinal complications.[31] The implications of reduced NSAIDs administration warrant further investigation to assess its broader benefits, particularly in high-risk patients.

Strengths and limitations of the study

This meta-analysis included only RCTs that enroled largely homogeneous populations of American Society of Anesthesiologists Physical Status (ASA) class I–II patients undergoing elective surgeries, ensuring greater generalisability of the results and enhancing the reliability of the findings.[26,27,28] Additionally, the analysis focused exclusively on adult patients receiving SESPB with spinal anaesthesia, excluding RCTs involving patients under general anaesthesia to provide a precise answer to a specific question within a less heterogeneous population.[15,19] Nevertheless, it is important to emphasise that meta-analyses should be viewed as hypothesis-generating. Therefore, while our results are promising, they remain speculative, and this study has several limitations:

• Timing of pain outcome assessment: Pain was evaluated 24 h postoperatively in all trials. Although this standardises comparisons, the analgesic effect of SESPB may diminish within this timeframe because some trials did not report pain outcomes at earlier intervals (i.e., 6–12 h). Future trials should include pain assessments at multiple intervals to better evaluate the temporal efficacy of SESPB compared with spinal anaesthesia.

• Limited number of trials: Although this meta-analysis is the first to focus specifically on SESPB, providing a foundation for future research, the number of available trials is small. Additional RCTs are needed to confirm and expand upon these promising findings.

• Outcome measurement variability: Differences in pain scales across studies (VAS in Behera S. et al. 2024[26] versus NRS in Satici M. et al. 2024[27] and Mermer A. et al. 2023[28]) may have introduced bias in pain outcome assessments. The VAS captures a broader emotional-affective component compared with the NRS, potentially influencing reported pain levels.[32,33] Moreover, although there was a statistically significant trend towards reduced postoperative pain, the decrease did not reach a full 1-point difference on the pain scale. This raises the question of whether the reduction can be considered clinically relevant, despite the significantly lower need for rescue opioid analgesics in the postoperative period.

• Heterogeneity in local anaesthetics: While the volume of anaesthetic used for SESPB was consistent across studies, the type of local anaesthetic varied. Notably, in Behera et al. (2024),[26] an adjunct (dexamethasone) was added to the local anaesthetic. Additionally, differences in the types of elective surgeries studied may have influenced the outcomes.

• Generalisability to broader populations: The included RCTs focused on healthy, noncritical patients. The efficacy of SESPB in elective surgeries involving more complex or critically ill populations remains unproven, and its use is still an area of ongoing research. As a relatively new block, SESPB needs to be applied across diverse surgical types to evaluate its efficacy in various clinical scenarios.

Despite these limitations, this meta-analysis provides valuable insights into the use of SESPB. As a relatively new block, SESPB shows promise in reducing the need for rescue opioid analgesics in the postoperative period and improving postoperative pain control.[34,35,36] Further higher-quality, larger-scale RCTs are needed to explore its efficacy in broader patient populations, refine outcome measures and standardise procedural techniques.

CONCLUSIONS

Pooled data from available RCTs demonstrate that combining SESPB with spinal anaesthesia in patients undergoing elective surgery reduces the need for rescue opioid analgesia in the postoperative period. This combination is also associated with a nonstatistically significant reduction in overall opioid consumption and a delayed requirement for rescue opioid administration during the postoperative period. Additionally, patients who received SESPB reported improved postoperative pain control 24 h after surgery; however, these findings should be interpreted with caution given the limited sample size. Larger, high-quality trials are needed to better establish clinically meaningful differences. Based on the observed benefits, incorporating SESPB alongside spinal anaesthesia may be considered for patients undergoing elective surgeries.

Data availability

The data for this systematic review and/or meta-analysis may be requested with reasonable justification from the authors (email to the corresponding author) and shall be shared upon request.

Authors contribution

EP: Conceptualisation, Visualisation, Data curation, Formal analysis, Resources, Project Administration, Data curation, Writing – original draft, Writing - Review and Editing, Supervision. FM: Conceptualisation, Data curation, Writing - Review and Editing, Writing – original draft. EP: Resources, Data curation. SS: Visualisation, Formal analysis, Writing - Review and Editing. GF: Conceptualisation, Writing - Review and Editing. PF: Conceptualisation, Data curation, Visualisation, Writing – original draft, Writing - Review and Editing.

Conflicts of interest

There are no conflicts of interest.

Presentation at conferences/CMEs and abstract publication

This study has never been presented at conferences/ CMEs or published as abstract before.

Disclosure of use of artificial intelligence (AI)-assistive or generative tools

The authors confirm that no AI tools or language models (LLMs) were used in the writing or editing of the manuscript, and no images were manipulated using AI.

Declaration of Use of Permitted Tools

The scales, scores, figures, and tables are freely available and not copyrighted.

Supplementary material

This article has supplementary material and can be accessed at this link. Supplementary Material at http://links.lww.com/IJOA/A32.

Supplementary Figure 1

Funnel plot of the primary outcome

Supplementary Figure 2

Forest plot of postoperative pain 12 h after surgery (VAS/NRS score). VAS = visual analogue scale, NRS = numerical rating scale, SE = standard error, OR = odds ratio

Supplementary Figure 3

Forest plot of time to the first opioid requirement after surgery (h). M-H = Mantel–Haenszel, CI = confidence interval, SESPB = sacral erector spinae plane block, IV = inverse variance

Supplementary Figure 4

Trial sequential analysis for the primary outcome. SESPB = sacral erector spinae plane block, RRR = relative risk reduction

Funding Statement

Nil.