Comparison of perioperative analgesic efficacy between serratus anterior plane block and thoracic paravertebral block in adult patients undergoing thoracic and breast surgeries: a systematic review and meta-analysis

Abstract

Background

Serratus anterior plane block (SAPB) and thoracic paravertebral block (TPVB) are widely used regional anesthesia techniques for postoperative analgesia and are generally considered safe and effective. However, the comparative efficacy remains inconclusive. This systematic review and meta-analysis of randomized controlled trials (RCTs) aims to evaluate the perioperative analgesic efficacy of SAPB versus TPVB in adult patients undergoing thoracic and breast surgeries.

Methods

A comprehensive literature search was conducted in PubMed, EMBASE, Web of Science, Cochrane library, ClinicalTrial.gov, and Google Scholar up to February 28, 2025. Primary outcomes included time to first analgesic request (TFAR), 24-h total analgesic consumption (TAC) postoperatively, and 24-h postoperative pain scores at rest. Secondary outcomes comprised pain scores at various postoperative timepoints, intraoperative fentanyl consumption, length of hospital stay, patient satisfaction with analgesia, and incidence of complications. A random-effect model was applied for the meta-analysis.

Results

Twenty-eight 28 RCTs comprising 1796 patients were included. No significant differences were found between SAPB and TPVB in TFAR (mean difference [MD] = -0.68 h, 95% confidence interval [CI]: -1.55 to 0.18, P = 0.122), 24-h pain scores at rest (MD = 0.14, 95%CI: -0.14 to 0.42, P = 0.334), other postoperative pain scores, length of hospital stay, patient satisfaction, or incidence of postoperative nausea and vomiting (risk ratio [RR] = 0.87, 95%CI: 0.63 to 1.20, P = 0.310). Despite statistically significant, the difference of 24-h TAC comparing SAPB to TPVB (MD = 1.73 mg intravenous morphine equivalents, 95%CI: 0.54 to 2.92, P = 0.005) did not exceed the minimal clinically important difference (MCID) of 10 mg. SAPB also resulted in greater intraoperative fentanyl consumption (MD = 13.85 mcg, 95%CI: 3.86 to 23.84, P = 0.007) but a significantly lower incidence of hypotension (RR = 0.39, 95%CI: 0.20 to 0.76, P = 0.006). Subgroup analyses showed that TPVB provided superior, but non-clinically significant, opioid-sparing benefits in thoracic procedures (3.38 mg) and when compared to superficial SAPB (3.11 mg).

Conclusion

SAPB offers comparable analgesic efficacy to TPVB, with a more favorable safety profile but slightly higher opioid consumption. However, the increased opioid use does not exceed the MCID. Therefore, SAPB is a clinically effective and safe alternative to TPVB for perioperative regional analgesia in thoracic and breast surgeries.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12871-025-03343-0.

Background

Postoperative pain following thoracic and breast surgeries remains a significant clinical concern, often leading to delayed recovery, impaired respiratory function, and reduced patient satisfaction [1, 2]. Despite advances in surgical techniques, particularly the adoption of video-assisted thoracoscopic surgery (VATS) which is less invasive than traditional thoracotomy, moderate to severe postoperative pain is still commonly reported [3, 4]. Inadequate pain control can compromise deep breathing and effective coughing, thereby increasing the risk of complications such as atelectasis, hypoxemia, and pulmonary infections [5]. Furthermore, poorly managed acute pain may progress to chronic postsurgical pain (CPSP), negatively impacting long-term quality of life [6].

Opioids have traditionally been the cornerstone of postoperative analgesia. Although effective, they are associated with numerous adverse effects, including nausea, vomiting, constipation, urinary retention, sedation, and respiratory depression [7]. These side effects can delay mobilization, prolong hospital stays, and contribute to the growing global concern over opioid misuse and dependence [8]. In this context, regional anesthesia has become a key component of multimodal analgesia strategies. It offers effective pain relief, reduces opioid consumption, and improves functional outcomes by directly targeting the nerve pathways involved in pain transmission [9].

The thoracic paravertebral block (TPVB) has long been considered a standard regional anesthetic technique for thoracic and breast surgeries [10, 11]. It provides unilateral somatic and sympathetic nerve blockade and has demonstrated efficacy in managing both acute and chronic postoperative pain [12, 13]. However, TPVB is technically demanding and carries the risk of serious complications, including pneumothorax, inadvertent dural puncture, vascular injury, and hematoma formation [14]. These limitations have driven interest in alternative regional techniques that offer comparable analgesia with improved safety.

One such alternative is the serratus anterior plane block (SAPB), first described by Blanco et al. in 2013 [15]. This ultrasound-guided technique involves the injection of local anesthetic either superficial or deep to the serratus anterior muscle at the midaxillary line. Specifically, the superficial approach injects local anesthetic between the latissimus dorsi and serratus anterior muscles, while the deep approach targets the plane between the serratus anterior and the ribs or external intercostal muscles [16]. SAPB achieves analgesia by blocking the lateral cutaneous branches of the thoracic intercostal nerves, as well as the long thoracic and thoracodorsal nerves. It has been associated with significant reductions in postoperative pain intensity and opioid requirements, along with a low incidence of complications [17–19]. Owing to its effective analgesia, technical simplicity, ease of learning, and favorable safety profile, SAPB is increasingly adopted in thoracic and breast surgical settings.

Although multiple randomized controlled trials (RCTs) have compared SAPB and TPVB, their findings are inconsistent. Some studies suggest equivalent analgesic efficacy, while others favor one technique over the other [20–23]. Given these discrepancies, a comprehensive synthesis of the existing evidence is needed to guide clinical practice. Therefore, this meta-analysis aims to systematically evaluate and compare the perioperative analgesic efficacy of SAPB and TPVB in adult patients undergoing thoracic and breast surgeries.

Methods

This systematic review and meta-analysis was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) [24].

Databases and strategies for literature search

A comprehensive literature search was conducted in PubMed, EMBASE, Web of Science, Cochrane library, and ClinicalTrial.gov from database inception to February 28, 2025. There were no language restrictions. Grey literature was additionally screened via Google Scholar. The search utilized a combination of free-text terms: “serratus anterior plane block”, “serratus plane block”, “serratus anterior block”, “thoracic paravertebral block”, “paravertebral block”, and “paravertebral nerve block”. Full search strategies are detailed in Additional file 1: Table S1. Reference lists of relevant reviews, meta-analyses, and original studies were also manually screened to identify any additional eligible trials.

Inclusion criteria

Studies were included based on the PICOS framework:

• Participants (P): Adult patients undergoing thoracic or breast surgeries.

• Intervention (I): SAPB.

• Comparator (C): TPVB.

• Outcomes (O): Primary outcomes included time to first analgesic request (TFAR), 24-h total analgesic consumption (TAC), and 24-h pain scores at rest postoperatively. Secondary outcomes included intraoperative fentanyl consumption, pains scores at rest and during coughing at multiple postoperative timepoints (0, 2, 4, 6, 8, 12 h), 24-h pain scores during coughing, patient satisfaction with analgesia, length of hospital stay, and perioperative complications (postoperative nausea and vomiting [PONV], hypotension, bradycardia, dizziness, pruritus, punctured pleura).

• Study design (S): RCT.

Exclusion criteria

Studies were excluded if they met any of the following conditions: (1) observational studies; (2) inclusion of pediatric patients; (3) combination of SAPB or TPVB with other regional blocks; (4) publication as case reports, reviews, meta-analyses, or conference abstracts; (5) full texts unavailable; or (6) insufficient data for outcome extraction.

Two reviewers independently screened all records, and discrepancies were resolved through discussion.

Risk of bias assessment

Two reviewers independently assessed the risk of bias using the Risk of Bias 2 (ROB 2) tool [25]. The five domains evaluated were: randomization process, deviations from the intended interventions, missing outcome data, measurement of the outcome, and selection of the reported result. Each domain was classified as having low risk of bias, some concerns, or high risk of bias. An overall judgment of “low risk” was assigned when all domains had low risk; “some concerns” if one or two domains raised concern; and “high risk” if at least one domain had high risk or if three or more domains raised concerns. Any disagreements were resolved through consensus.

Data extraction

For each included study, the following information was extracted: first author, publication year, country, surgery type, regional block protocols, postoperative analgesia protocols, sample size, age, body mass index, American Society of Anesthesiologists (ASA) classifications, mean and standard deviation (SD) values for continuous outcomes, and event counts for categorical outcomes. When only medians with ranges or interquartile ranges were reported, values were converted to means and SDs using the methods described by Luo et al. and Wan et al. [26, 27]. For 24-h TAC, opioid consumption was standardized to intravenous morphine equivalents using the conversion tool from GlobalRPh website (https://www.globalrph.com/narcotic), assuming 0% incomplete cross-tolerance. Data extraction was conducted independently by two reviewers, with disagreements resolved through discussion.

Statistical analysis

Heterogeneity across studies was assessed using the I² statistic, with thresholds of < 25%, 25–50%, and > 50% indicating low, moderate, and high heterogeneity, respectively. In addition, 95% prediction intervals (95%PI) were calculated for key outcomes, including TFAR, 24-h TAC, 24-h pain scores at rest, intraoperative fentanyl consumption, and PONV, to estimate the range where the effect size of a future study is expected to fall [28]. For continuous outcomes, mean differences (MD) with corresponding 95% confidence intervals (95%CI) were calculated; for categorical outcomes, risk ratios (RR) with 95%CIs were used. A random-effect model was employed for all pooled analyses, regardless of heterogeneity level. Subgroup analyses were performed for primary outcomes based on surgery type (breast, thoracic), SAPB type (deep, superficial), injection type (single injection, continuous injection), TPVB injection level (single-level, bi-level), risk of bias (low ROB, some concerns/ high ROB). Additional subgroup analyses examined combined effects of surgery and SAPB type, including breast surgery + deep SAPB, breast surgery + superficial SAPB, thoracic surgery + deep SAPB, and thoracic surgery + superficial SAPB. Subgroup differences were evaluated using meta-regression. Sensitivity analysis was performed using a leave-one-out approach. Publication bias was assessed through visual inspection of funnel plot symmetry and Egger’s test. When bias was suspected, a trim-and-fill analysis was performed to evaluate its impact on the pooled results. All analyses were conducted using STATA version 16.0 (StataCorp, TX, USA). A two-sided P-value < 0.05 was considered statistically significant.

Results

Baseline characteristics of studies included in the meta-analysis

A total of 1,065 records were identified through a systematic literature search. After removing duplicates, 745 unique articles remained for title and abstract screening (Fig. 1). Of these, 697 were excluded as irrelevant, and 48 full-text articles were assessed for eligibility (Additional file 1: Table S2). Ultimately, 28 studies met the inclusion criteria and were included in the meta-analysis [20–23, 29–52]. These studies were conducted in Egypt (n = 8), China (n = 7), India (n = 7), Turkey (n = 2), France (n = 1), Ireland (n = 1), Poland (n = 1), and USA (n = 1), encompassing a total of 1796 patients with 905 receiving SAPB and 891 receiving TPVB. Surgery procedures included breast surgery (n = 12), thoracotomy (n = 4), and VATS (n = 12). Thirteen trials utilized deep SAPB, another 13 used superficial SAPB, and one study included both approaches [41]. One trial included two separate arms for deep and superficial SAPB [44], which were treated as two independent datasets in the quantitative synthesis. To avoid double-counting, the sample size of the shared TPVB group was divided evenly, while the mean and SD remained unchanged. For TPVB, 23 trials used single-level injection, and five employed bi-level injections [33, 39, 40, 42, 43]. Most studies adopted a single-injection technique for both SAPB and TPVB, with only three trials using a continuous catheter-based injection [34, 38, 51]. The baseline characteristics of the included studies are summarized in Table 1.

Fig. 1.

Flowchart of literature search and selection

Table 1.

Baseline characteristics of studies included in meta-analysis

Study	Surgery type	SAPB type	Sample size (SAPV/TPVB)	Mean age, years (SAPV/TPVB)	SAPB protocol	TPVB protocol	Postoperative analgesia
Aly 2018 [22]	Thoracotomy	Superficial	30/28	55.4/53.7	30 ml of 0.5% bupivacaine	20 ml of 0.5% bupivacaine	Diclofenac, paracetamol, morphine PRN
Amin 2018 [23]	Mastectomy	Deep	30/30	45/42	0.4 ml/kg of 0.25% bupivacaine	15–20 ml of 0.25% bupivacaine	Morphine PRN
Arora 2021	MRM	Deep	20/20	50.8/48.2	0.4 ml/kg of 0.5% ropivacaine	0.4 ml/kg of 0.5% ropivacaine	Diclofenac, tramadol PRN
Baytar 2021 [30]	VATS	Deep	31/31	47.6/51.2	0.4 ml/kg of 0.25% bupivacaine	0.4 ml/kg of 0.25% bupivacaine	Paracetamol, tenoxicam, tramadol PCA
But 2024 [31]	Breast cancer surgeries	Deep	24/30	66.5/66.5	10 ml of 2% lidocaine and 10 ml of 0.5% bupivacaine	10 ml of 2% lidocaine and 10 ml of 0.5% bupivacaine	Morphine PCA
Das 2022 [32]	Thoracotomy	Superficial	29/28	53.45/45.21	30 ml of 0.5% bupivacaine and 2% lignocaine	30 ml of 0.5% bupivacaine and 2% lignocaine	Fentanyl PRN
Eldemrdash 2019 [45]	MRM	Deep	25/25	50.2/55.1	20 ml of 2% articaine	20 ml of 2% articaine	Morphine PCA
Elsakka 2023 [46]	MRM	Deep	30/30	49.83/49.77	10 ml of 0.5% bupivacaine, 4 ml of fentanyl (10 μg/ml)	10 ml of 0.5% bupivacaine, 4 ml of fentanyl (10 μg/ml)	Acetaminophen, ketorolac PRN
Gabriel 2021 [33]	Non-mastectomy breast surgery	Deep	49/51	55/53	20 ml (unilateral surgery) or 32 ml (bilateral surgery) of 0.5% ropivacaine	20 ml (unilateral surgery) or 32 ml (bilateral surgery) of 0.5% ropivacaine	Fentanyl PRN, hydromorphine PRN, oxycodone PRN
Gandhi 2023 [47]	MRM	Superficial	39/39		20 ml of 0.5% bupivacaine	20 ml of 0.5% bupivacaine	Fentanyl PRN
Gupta 2017 [20]	MRM	Superficial	25/25	48.9/50	20 ml of 0.5% bupivacaine	20 ml of 0.5% bupivacaine	Morphine PCA
Hanley 2020 [34]	VATS	Deep	20/20	60/64	A maximum of 40 ml (20 mg/kg) of levobupivacaine followed by continuous infusion of 0.125% levobupivacaine at 8 ml/h for 48 h	20 ml of 0.25% levobupivacaine, then continuous infusion of 0.125% levobupivacaine at 8 ml/h for 48 h	Paracetamol, gabapentin, oxycodone PRN
Helmy 2023 [48]	Mastectomy	Deep	25/25	52.8/49	20 ml of 0.25% bupivacaine	20 ml of 0.25% bupivacaine	NR
Jain 2020 [35]	Mastectomy	Deep	15/15	60.87/44.47	30 ml of 0.375% ropivacaine	20 ml of 0.375% ropivacaine	Fentanyl PCA
Lalwani 2024 [49]	VATS	Deep	40/40	42.6/41.4	20 ml of 0.5% levobupivacaine	20 ml of 0.5% levobupivacaine	Tramadol PRN
Leviel 2024 [36]	VATS	Deep	52/52	66/63	40 ml of 0.2% ropivacaine	20 ml of 0.2% ropivacaine	Paracetamol, nefopam, ketoprofen, tramadol, oxycodone PRN
Liu 2022 [37]	VATS	Superficial	44/44	59.16/59.23	20 ml of 0.375% ropivacaine	20 ml of 0.375% ropivacaine	Sufentanyl PCA
Maamoon 2024 [50]	VATS	Superficial	40/40	40.95/41.93	A maximum of 40 ml (0.4 ml/kg) of 0.25% bupivacaine	A maximum of 40 ml (0.4 ml/kg) of 0.25% bupivacaine	Paracetamol, ketorolac, nalbuphine PRN
Mahran 2020 [51]	MRM	Superficial	30/30	45.2/44.6	20 ml of 0.25% levobupivacaine followed by continuous infusion of 0.125% levobupivacaine at 5 ml/h	20 ml of 0.25% levobupivacaine, then continuous infusion of 0.125% levobupivacaine at 5 ml/h	Morphine PCA
Patel 2020 [38]	Thoracotomy	Superficial	24/26	40.2/38.34	A maximum of 30 ml (0.4 ml/kg) of 0.375% ropivacaine followed by continuous infusion of 0.2% ropivacaine at 0.1 ml/kg/h for 24 h	0.1 mg/kg of 0.2% ropivacaine followed by continuous infusion of 0.2% ropivacaine at 0.1 ml/kg/h for 24 h	Paracetamol, morphine PRN, diclofenac PRN
Qiu 2021 [39]	VATS	Superficial	29/30	56/58	30 ml of 0.375% ropivacaine	30 ml of 0.375% ropivacaine	Sufentanyl, dezocine, tramadol PRN, oxycodone PRN, lornoxicam PRN
Saad 2018 [21]	Thoracotomy	Superficial	30/30	52/55.7	30 ml of 0.5% bupivacaine	20 ml of 0.5% bupivacaine	Ketorolac PRN, morphine PRN
Shi 2022 [40]	VATS	Superficial	25/25	43.6/44.2	20 ml of 0.3% ropivacaine	30 ml of 0.3% ropivacaine	Sufentanyl PCA, parecoxib PRN
Ulger 2024 [41]	VATS	Combination of deep and superficial SAPB	30/30	56/46	30 ml of 0.25% bupivacaine	30 ml of 0.25% bupivacaine	Paracetamol, dexketoprofen, morphine PCA, tramadol PRN
Wang 2022	VATS	Superficial	46/46	59/58.3	3 mg/kg of 0.375% ropivacaine	3 mg/kg of 0.375% ropivacaine	Sufentanyl PCA, flurbiprofen PRN
Wang 2023 [43]	MRM	Deep	49/49	44/46	40 ml of 0.25% ropivacaine	40 ml of 0.25% ropivacaine	NR
Zhang 2019 [52]	VATS	Superficial	30/30	59.2/57.4	30 ml of 0.4% ropivacaine	30 ml of 0.4% ropivacaine	Sufentanyl PCA, pethidine PRN
Zhang 2022 [44]	VATS	Arm 1: deep; arm 2: superficial	22/22//22	55/57.95/58.64	20 ml of 0.5% ropivacaine	20 ml of 0.5% ropivacaine	Hydromorphone PCA, flurbiprofen PRN

MRM Modified radical mastectomy, NR Not reported, PCA Patient-controlled analgesia, PRN as requested by the patient, SAPB Serratus anterior plane block, TPVB Thoracic paravertebral block, VATS Video-assisted thoracoscopic surgery

ROB assessment

According to the ROB 2 tool (Fig. 2), one study was rated as having high risk of overall bias [32], nine studies had some concerns [23, 31, 35, 37, 40, 44, 46, 48, 50], and the remaining studies were assessed as having low risk of overall bias.

Fig. 2.

Risk of bias assessment for each study. D1: Randomization process; D2: Deviations from the intended interventions; D3: Missing outcome data; D4: Measurement of the outcome; D5: Selection of the reported result

TFAR

Eighteen studies, involving 588 patients in the SAPB group and 585 in the TPVB group, were included. A random-effect meta-analysis revealed no significant difference in TFAR between the two groups (MD = −0.68 h, 95%CI: −1.55 to 0.18, P = 0.122; 95%PI: −4.62 to 3.25; Fig. 3). Subgroup analyses stratified by surgery type (Additional file 2: Fig. S1), SAPB type, injection technique, TPVB injection level, and ROB level showed consistent findings (Additional file 1: Table S3). One trial employing continuous infusion reported a significantly shorter TFAR in the SAPB group (270.2 ± 37.7 min versus 368.0 ± 36.0 min, P < 0.001) [51].

Fig. 3.

Forest plot for time to first analgesic request. Each study is represented by a square (proportional to the study weight) and a horizontal line (95%CI). The green diamond represents the pooled mean difference. CI: confidence interval; SAPB: serratus anterior plane block; SD: standard deviation; TPVB: thoracic paravertebral block

24-h TAC postoperatively

Thirteen studies (SAPB: n = 362; TPVB: n = 367) were included. Substantial heterogeneity was observed (I² = 94.2%). The SAPB group demonstrated significantly higher 24-h TAC (MD = 1.73 mg intravenous morphine equivalents, 95%CI: 0.54 to 2.92, P = 0.005; 95%PI: −2.95 to 6.41; Fig. 4). In subgroup analysis, TAC was comparable in breast surgery (MD = 0.69 mg, 95%CI: −0.75 to 2.13, P = 0.347) but significantly higher in the SAPB group for thoracic surgery (MD = 3.38 mg, 95%CI: 1.64 to 5.13, P < 0.001; Additional file 2: Fig. S2). Deep SAPB was associated with similar TAC compared to TPVB (MD = −0.09 mg, 95%CI: −2.07 to 1.89, P = 0.928), while superficial SAPB resulted in significantly higher TAC (MD = 3.11 mg, 95%CI: 1.99 to 4.24, P < 0.001; Additional file 2: Fig. S3). Meta-regression revealed significant subgroup differences (P = 0.021 and 0.002). Further subgroup analyses showed that TPVB was favored in single-injection, continuous-injection, single-level TPVB, and low ROB subgroups (Additional file 1: Table S4).

Fig. 4.

Forest plot for 24-h total analgesic consumption (intravenous morphine equivalents) postoperatively. Each study is represented by a square (proportional to the study weight) and a horizontal line (95%CI). The green diamond represents the pooled mean difference. CI: confidence interval; SAPB: serratus anterior plane block; SD: standard deviation; TPVB: thoracic paravertebral block

24-h pain scores at rest

Twenty trials involving 629 SAPB patients and 605 TPVB patient were included. No significant difference was found in 24-h pain scores at rest (MD = 0.14, 95%CI: −0.14 to 0.42, P = 0.334; 95%PI: −1.07 to 1.35; Fig. 5). Most subgroup analyses yielded similar results (Additional file 1: Table S5), although one continuous-injection trial favored SAPB [34].

Fig. 5.

Forest plot for 24-h pain scores postoperatively. Each study is represented by a square (proportional to the study weight) and a horizontal line (95%CI). The green diamond represents the pooled mean difference. CI: confidence interval; SAPB: serratus anterior plane block; SD: standard deviation; TPVB: thoracic paravertebral block

Intraoperative fentanyl consumption

Eight trials reported intraoperative fentanyl consumption. The SAPB group required more fentanyl (MD = 13.85 mcg, 95%CI: 3.86 to 23.84, P = 0.007; 95%PI: −15.15 to 42.85; Additional file 2: Fig. S4). This difference was not significant in breast surgery (MD = 7 mcg, 95%CI: −3.42 to 17.42, P = 0.188), but significantly favored TPVB in thoracic surgery (MD = 27.75 mcg, 95%CI: 11.50 to 44.00, P < 0.001; Additional file 2: Fig. S5). Meta-regression revealed a significant subgroup difference (P = 0.035).

Pain scores at various postoperative timepoints

Meta-analyses revealed no significant differences in pain scores at rest or during coughing at 0, 2, 4, 6, 8, and 12 h postoperatively (Additional file 2: Figs. S6-S11). Similarly, 24-h pain scores during coughing did not differ significantly (Additional file 2: Fig. S12).

Length of hospital stay

A meta-analysis of nine trials involving 604 patients found no significant difference in the length of hospital stay (MD = 0.04 days, 95%CI: −0.13 to 0.22, P = 0.623, Additional file 2: Fig. S13).

Patient satisfaction with analgesia

Six trials reported patient satisfaction data. Satisfaction rates were 76.8% (159/207) in the SAPB group and 82.9% (170/205) in the TPVB group. No significant difference was observed (RR = 0.95; 95% CI: 0.84 to 1.10; P = 0.498; Additional file 2: Fig. S14).

Complications

Across 15 studies involving 869 patients, 126 cases of PONV were reported. There was no significant difference in PONV incidence between groups (RR = 0.87, 95%CI: 0.63 to 1.20, P = 0.391; 95%PI: 0.61 to 1.24; Fig. 6). Similarly, no significant differences were found in rates of bradycardia, dizziness, pruritus, or punctured pleura (Additional file 2: Figs. S15). Notably, all six cases of punctured pleura occurred in the TPVB group [34, 49]. The incidence of hypotension was significantly lower in the SAPB group (RR = 0.39, 95%CI: 0.20 to 0.76, P = 0.006; Fig. 7).

Fig. 6.

Forest plot for incidence of postoperative nausea and vomiting. Each study is represented by a square (proportional to the study weight) and a horizontal line (95%CI). The green diamond represents the pooled risk ratio. CI: confidence interval; SAPB: serratus anterior plane block; TPVB: thoracic paravertebral block

Fig. 7.

Forest plot for incidence of hypotension. Each study is represented by a square (proportional to the study weight) and a horizontal line (95%CI). The green diamond represents the pooled risk ratio. CI: confidence interval; SAPB: serratus anterior plane block; TPVB: thoracic paravertebral block

Analgesic efficacy in combinations of surgery type and SAPB type

Analysis by combinations of surgery type and SAPB approach is presented in Table 2. In breast surgery, deep SAPB provided analgesia comparable to TPVB, while superficial SAPB was associated with earlier TFAR (MD = −1.55 h, 95%CI: −1.81 to −1.29, P < 0.001) and higher 24-h TAC (MD = 2.11 mg, 95%CI: 1.18 to 3.04, P < 0.001). In thoracic surgery, deep SAPB again showed similar efficacy to TPVB, whereas superficial SAPB resulted in significantly higher 24-h TAC (MD = 4.02 mg, 95%CI: 2.55 to 5.49, P < 0.001).

Table 2.

Results for primary outcomes according to combinations of surgery type and SAPB type

Subgroup	No. of studies and patients	I2, %	MD (95%CI)	P
Breast surgery + DSAPB
TFAR	6 (179/179)	96.9	0.01 (−1.41 to 1.42)	0.991
24-h TAC	5 (114/120)	89.3	−0.40 (−2.79 to 1.98)	0.740
24-h pain scores at rest	4 (124/124)	83.5	0.02 (−0.62 to 0.67)	0.942
Breast surgery + SSAPB
TFAR	3 (94/94)	9.0	−1.55 (−1.81 to −1.29)	< 0.001
24-h TAC	3 (94/94)	83.4	2.11 (1.18 to 3.04)	< 0.001
24-h pain scores at rest	1 (25/25)	NA	−0.56 (−1.17 to 0.05)	0.073
Thoracic surgery + DSAPB
TFAR	2 (71/71)	94	−3.69 (−10.64 to 3.26)	0.298
24-h TAC	1 (31/31)	NA	1.26 (0.27 to 2.25)	0.013
24-h pain scores at rest	4 (125/114)	62.4	−0.24 (−0.74 to 0.25)	0.332
Thoracic surgery + SSAPB
TFAR	7 (244/241)	98.3	−0.41 (−2.40 to 1.58)	0.687
24-h TAC	4 (123/122)	75.9	4.02 (2.55 to 5.49)	< 0.001
24-h pain scores at rest	10 (325/314)	92.2	0.34 (−0.10 to 0.78)	0.126

DSAPB Deep serratus anterior plane block, MD Mean difference, NA Not applicable, SSAPB Superficial serratus anterior plane block, TAC Total analgesic consumption in intravenous morphine equivalents, TFAR Time to first analgesia request, TPVB Thoracic paravertebral block

Sensitivity analysis and publication bias

Leave-one-out sensitivity analysis showed that no individual study significantly altered the pooled results. Funnel plot inspection and Egger’s test (Additional file 1: Table S6) indicated no evidence of publication bias for all primary outcomes (Additional file 2: Fig. S16-S18) and most secondary outcomes, with the exception of intraoperative fentanyl consumption (P = 0.032). To account for small-study effects, a trim-and-fill analysis was performed, which imputed two hypothetical negative unpublished studies mirroring the included positive studies that caused the asymmetry. This analysis rendered the difference of intraoperative fentanyl consumption non-significant (MD = 9.31 mcg, 95%CI: −1.04 to 19.66; Fig. 8).

Fig. 8.

Funnel plot after trim-and-fill analysis of intraoperative fentanyl consumption. Black circle: observed studies; red circle: imputed studies

Discussion

This systematic review and meta-analysis included 28 RCTs comprising 1796 patients to compare the analgesic efficacy and safety of SAPB and TPVB in thoracic and breast surgeries. The findings demonstrate that SAPB and TPVB provide comparable analgesia in several outcomes, including TFAR, postoperative pain intensity, patient satisfaction, and PONV incidence. However, TPVB was associated with significantly lower 24-h opioid consumption and intraoperative fentanyl use, particularly in thoracic surgeries and when compared with superficial SAPB. These nuanced results support individualized analgesic strategies in clinical settings.

Pooled analysis revealed no statistically significant difference in TFAR between SAPB and TPVB, suggesting similar early postoperative analgesia durations. Subgroup analyses stratified by surgery type, injection technique, and SAPB approach confirmed the robustness of this finding. Notably, in the study by Mahran et al. [52], continuous SAPB resulted in a significantly shorter TFAR compared to TPVB, indicating that infusion-based techniques may influence SAPB performance. Additionally, in breast surgery, superficial SAPB was associated with an earlier need for rescue analgesia (Table 2), as all three trials in this subgroup favored TPVB for prolonged analgesic duration [20, 47, 51].

TPVB was associated with significantly lower 24-h TAC, with a MD of 1.73 mg intravenous morphine equivalents. This effect was largely attributable to the inferior performance of superficial SAPB (Additional file 2: Fig. S3). When stratified by surgery type, superficial SAPB consistently resulted in greater morphine use compared to TPVB (Table 2). Conversely, deep SAPB yielded comparable morphine consumption to TPVB, consistent with multiple trials showing that deep SAPB can provide sustained analgesia following both breast and thoracic procedures (Additional file 2: Fig. S3). Interestingly, Amin et al. reported superior analgesia with deep SAPB compared to TPVB in terms of delayed TFAR and reduced 24-h TAC in breast surgery [23]. However, both regional blocks in this trial were performed at the end of surgery and before recovery from general anesthesia.

Our findings regarding the differential efficacy of deep versus superficial SAPB contrast with those of a previous meta-analysis that directly compared these two approaches [53]. That study, which included seven RCTs, found no significant differences in TFAR, 24-h TAC, pain intensity, or PONV. However, the lack of stratification by surgical type in that study may have masked potential differences. Although the differences in opioid use identified in our analysis (1.73 mg overall; 2.11 mg in breast surgery + superficial SAPB; 4.02 mg in thoracic surgery + superficial SAPB) were statistically significant, they did not exceed the MCID for postoperative opioid consumption, which is commonly considered to be 10 mg intravenous morphine equivalents or 30 mg oral morphine equivalents [54, 55]. Nonetheless, our findings underscore the need for future trials evaluating the comparative efficacy of deep versus superficial SAPB.

There were no significant differences between SAPB and TPVB in 24-h pain scores at rest or during coughing, nor at multiple postoperative time points up to 12 h. The absolute differences in pain scores ranged from 0.01 to 0.21 on the Visual Analog Scale (VAS), far below the MCID of 1.0 point on a 10-point scale [56]. However, intraoperative fentanyl use was significantly higher in the SAPB group, especially during thoracic procedures, possibly due to limited visceral and sympathetic blockade of SAPB. Nevertheless, this difference became non-significant after trim-and-fill analysis, suggesting the influence of small-study effects.

Regarding safety outcomes, there were no significant differences in the incidence of PONV, pruritus, dizziness, or bradycardia. Notably, all reported cases of pleural punctures occurred in the TPVB group, highlighting the higher complication risk associated with deeper, neuraxial-adjacent techniques [37, 42]. In contrast, SAPB was associated with a significantly lower incidence of hypotension, likely due to its more superficial anatomical location. TPVB, owing to its proximity to the epidural space, may allow local anesthetic spread to the sympathetic chain, leading to greater hemodynamic fluctuations [57].

Injection technique and block level represent additional variables of interest. Continuous SAPB or TPVB was employed in only three studies, which reported enhanced duration and intensity of analgesia in continuous injection [34, 38, 51]. Bi-level TPVB was used in only five studies [33, 39, 40, 42, 43], and subgroup analyses revealed no significant differences between single- and bi-level injections. Given the theoretical advantage of broader dermatomal coverage, further research on bi-level block approaches is warranted.

From a clinical perspective, SAPB offers a technically simpler and safer alternative to TPVB, particularly in breast surgery or when TPVB is contraindicated. However, TPVB may be preferable in thoracic surgery or when maximal opioid-sparing effects are desired, especially over superficial SAPB. Deep SAPB may serve as a reasonable compromise, balancing efficacy with a more favorable safety profile. Future research should aim to standardize block techniques and evaluate cost-effectiveness. Additional RCTs comparing catheter-based SAPB and TPVB are needed to clarify the role of continuous infusion in optimizing block efficacy.

This meta-analysis has several strengths over previous studies [19, 58–60]. It includes a large number of RCTs conducted across diverse surgical populations and geographic regions. Furthermore, comprehensive subgroup and meta-regression analyses were employed to explore sources of heterogeneity and to assess the influence of key covariates such as SAPB type, injection method, and surgery type. Nonetheless, substantial heterogeneity was observed in most outcomes, particularly in TFAR, 24-h TAC and 24-h pain scores at rest. Some included trials even yielded contradictory results. This heterogeneity likely reflects variability in surgical techniques, block protocols, anesthetic regimens, and postoperative pain management across studies. Although we attempted to account for these factors through subgroup and meta-regression analyses, residual confounding cannot be ruled out. Therefore, the reliability of the pooled estimates is limited, and the findings should be interpreted with caution. The second limitation is that nearly one-third of included RCTs had some concerns or high risk according to ROB 2 tool, which may influence the certainty of our conclusions. Subgroup analysis stratified by ROB level revealed that the difference of 24-h TAC was statistically significant in the “low ROB” subgroup but not in the “high ROB or some concerns” subgroup. One trial with some concerns in outcome measurement found significantly higher 24-h TAC in TPVB compared to SAPB [23], which was in opposite direction of other trials. The last limitation of our study is the absence of long-term outcomes such as CPSP, which affects over 40% of patients following VATS [61]. A prior network meta-analysis reported a lower risk of CPSP at 2–3 months postoperatively in the TPVB group compared to SAPB [62]. However, this conclusion was based on a small sample size [62]. Future RCTs are urgently warranted to determine whether SAPB and TPVB differ in their long-term effects on CPSP risk.

Conclusions

In summary, both SAPB and TPVB provide effective postoperative analgesia for thoracic and breast surgeries. Although statistically significant, the differences in opioid consumption between the two techniques do no exceed the MCID. Given its favorable safety profile and ease of conduction, SAPB, particularly the deep approach, remains a viable and effective alternative to TPVB.

Abbreviations

CI

Confidence interval

CPSP

Chronic post-surgery pain

MCID

Minimal clinically important difference

MD

Mean difference

PI

Prediction interval

PONV

Postoperative nausea and vomiting

RCT

Randomized controlled trial

ROB

Risk of bias

RR

Risk ratio

SAPB

Serratus anterior plane block

SD

Standard deviation

TAC

Total analgesic consumption

TFAR

Time to first analgesic request

TPVB

Thoracic paravertebral block

VATS

Video-assisted thoracoscopic surgery

Authors’ contribution

JW contributed to conception and design of this study. JW and TL performed literature search, data extraction and formal analysis. JW interpreted the results and drafted the manuscript. Both authors critically revised the manuscript and approved the final submission of the manuscript.

Funding

None.

Data availability

All data generated or analysed during this study are included in this published article and its supplementary information files.

Declarations

Ethics approval and consent to participate

This study was conducted in accordance with the Declaration of Helsinki.

Consent for publication

Not applicable.

Competing interests

The authors declare no competing interests.