Rectus sheath block for postoperative analgesia in abdominal surgery: A systematic review and meta-analysis of randomized controlled trials

ABSTRACT

The rectus sheath block is a potentially effective regional anesthetic technique for postoperative analgesia. However, evidence regarding its effectiveness across different surgical approaches and comparator techniques has remained inconsistent. We conducted a meta-analysis to evaluate the postoperative analgesic effectiveness of the rectus sheath block in abdominal surgery. Our study adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. In October 2025, we searched four databases (PUBMED, OVID Medline, SCOPUS, and Web of Science) for randomized controlled trials assessing the analgesic efficacy of the rectus sheath block following abdominal surgery. The primary outcomes were pain scores at rest measured at 0–2, 10–12, and 12–24 hours postoperatively. The secondary outcome was postoperative 24-hour intravenous morphine-equivalent consumption. Thirty-one randomized controlled trials involving 1076 participants who received the rectus sheath block and 1,065 who received alternative analgesic care were included. The rectus sheath block significantly reduced postoperative pain at 0–2 hours (mean difference [MD], −1.46, 95% CI, [ −2.26 to −0.66]; P < 0.001), 10–12 hours (MD, −0.94, 95% CI, [ −1.40 to −0.48]; P < 0.001), and 12–24 hours (MD, −0.65, 95% CI, [ −1.07 to −0.23]; P = 0.002). Twenty four-hour intravenous morphine-equivalent consumption was significantly lower with the rectus sheath block (MD, −7.40, 95% CI, [ −11.86 to −2.94]; P = 0.001). Rectus sheath block was associated with reduced postoperative pain scores and reduced opioid use in the first 24 hours after abdominal surgery.

Clinical trial registration: CRD420251208643 (PROSPERO).

Introduction

The rectus sheath block (RSB) was first introduced into clinical practice in 1899 to relax the anterior abdominal muscles during laparotomies before the advent of neuromuscular blockade.[1] Since then, this nerve block has been increasingly used in surgeries requiring midline abdominal incisions to reduce opioid use and postoperative pain in both open and laparoscopic procedures.[2,3] The modern version of the RSB involves an ultrasound-guided injection of a local anesthetic into the plane between the rectus abdominis muscle and the posterior rectus sheath, targeting the ventral rami of the seventh to eleventh thoracic nerves and the subcostal nerve.[4] Advancements in ultrasound visualization technology have significantly improved the precision and safety of this regional anesthetic technique.[5] Injection can be performed unilaterally or bilaterally, as a single injection or as a catheter-based technique, or through surgical and laparoscopic interventions.[6,7,8]

Previous reviews investigating the analgesic effects of the RSB have highlighted its potential in managing postoperative pain, but have been limited in their search and scope.[9] In 2021, a review of the analgesic efficacy of the RSB for postoperative pain included only nine studies, focusing on adult laparoscopic procedures.[10] In 2022, the effectiveness of the RSB for pediatric umbilical hernia repairs was investigated, but the review was limited to four studies.[11] More recently, a 2023 network meta-analysis evaluated 16 studies, including both single-injection and continuous RSB, but was limited to adults undergoing midline laparotomy.[2] The most comprehensive review to date evaluated 20 studies and includes the RSB in adult, pediatric and both open and laparoscopic procedures.[12]

No systematic review has evaluated the RSB against the full spectrum of comparator anesthetic modalities used in abdominal surgery, leading to a limited understanding of how its analgesic effectiveness varies across these different settings. An updated review of the literature is necessary since more diverse randomized controlled trials (RCTs) have been published.

This study aimed to perform a systematic review and meta-analysis of current RCT data on the analgesic efficacy of RSB at 0–2, 10–12, and 12–24 hours following abdominal surgery, as well as 24-hour postoperative opioid requirements.

Methods

This study was a systematic review and meta-analysis of all published data up to October 27, 2025. The review protocol was registered on PROSPERO[13] (registration number: CRD420251208643). The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines[14] were used to report the findings [Supplementary Table S1].

Eligibility criteria

Studies were selected using the PICOS (Population, Intervention, Comparator, Outcome, and Study) framework as follows: the population included patients of any age who underwent abdominal surgery. The intervention was the perioperative use of the RSB. The comparator included any of the following controls: no procedural intervention, sham block, or local anesthesia (wound infiltration - covering subcutaneous, intra-incisional, and supra-fascial infiltration; intraperitoneal instillation).

All studies using a no-intervention comparator administered multimodal analgesia, therefore “no intervention” refers to the absence of regional block rather than the absence of analgesic therapy.

The primary outcome was postoperative pain at rest at various specified times during recovery (0–2, 10–12, and 12–24 hour), reported using a numerical pain scale. The secondary outcome was 24-hour postoperative intravenous (IV) morphine milligram equivalent consumption. The studies of interest were RCTs.

Information sources and search strategy

PUBMED, OVID Medline, SCOPUS, and Web of Science were searched from inception to October 27, 2025, to identify relevant studies. A manual search strategy was also used to find studies not retrieved through the electronic search. The complete search strategy is available in the Supplementary material [Supplementary Table S2].

Study selection and data extraction

All studies were imported into the Covidence systematic review tool.[15] Titles, abstracts, and full-text articles were independently screened and assessed for suitability by two investigators (ELR and SDJ). Disagreements were resolved through consensus discussion.

Studies were excluded if they did not include the RSB technique, were technical descriptions, used combined blocks, did not include human models, or were non-randomized. Reasons for excluding the studies from the retrieved publications are detailed in Supplementary Table S3.

Data from eligible studies were extracted into the Covidence software and exported to a Microsoft Excel (version 16.103.2; Microsoft Corporation, Redmond, WA, USA) spreadsheet by one investigator (ELR).

Extracted variables included the following study characteristics: (1) pain scale data (type, minimum and maximum values); (2) surgical data (procedure, technique); (3) RSB data (drug regimen, route and timing of administration); (4) postoperative analgesia regimen; (5) all data on postoperative pain scores (mean or median values, standard deviation or interquartile range); (6) all data on postoperative opioid consumption (mean or median values, standard deviation or interquartile range).

When a study involved more than two arms, data were extracted from each relevant group only if different participants were used.

If data were only available graphically, the values were extracted using the pixel-based computer software “PlotDigitizer,”[16] an online tool that enables the extraction of numerical data from plot images.

If multiple pain scores were available within an outcome interval in a study, the time point closest to the midpoint of the interval was chosen for analysis. If several measures were equally close to the midpoint, the later time point was selected. This method ensured one data point per outcome per study, while reducing the risk of selective reporting bias related to specific time points.

Pain scores measured on Likert-type scales were standardized to a 0–10 scale for analysis. Scales that could not be converted to an equivalent 0–10 unit were excluded from mean-difference (MD) pooling and analyzed in a separate sensitivity analysis using standardized mean differences (SMD). These measures were not included in subgroup analyses.

Non-morphine opioids were converted to IV morphine milligram equivalents using standardized equianalgesic ratios. Only IV tramadol (mg) and IV fentanyl (µg) required conversion, using factors of 0.1 and 0.01, respectively, according to Chung et al.[17]

Continuous variables reported as medians with ranges were converted to means and standard deviations using the method of Hozo et al.[18] Continuous variables reported as medians with interquartile ranges were converted using the method of Wan et al.[19]

Authors were contacted directly for missing relevant data.

Bias assessment

The Cochrane Risk of Bias 2.0 tool was used to assess the risk of bias in all RCTs.[20] Risk of bias was evaluated across five categories, including (1) bias from the randomization process; (2) bias due to deviations from the intended interventions; (3) bias from missing outcome data; (4) bias in measuring the outcome; and (5) bias in selecting the reported results. This resulted in an overall RoB judgement of “high,” “some concerns,” or “low.” These decisions were displayed graphically using the RoB 2 tool, developed by the Cochrane Bias Methods Group.[21]

Assessment of evidence quality

The Grading of Recommendations, Assessment, Development, and Evaluations (GRADE)[22] framework was used to assess the strength of the evidence base. These guidelines classify the evidence for pooled outcomes using predefined criteria, such as study quality, consistency, directness, precision, and publication bias. GRADE assessments were summarized in an evidence profile table and a summary of findings (SoF) table.[23]

Statistical analysis

A random effects model was used. Continuous outcomes were pooled and assessed using MD, with 95% confidence intervals (CI). When a reported SD was zero, it was imputed using the median of available SDs from studies reporting the same outcome to allow inclusion in the meta-analysis. Heterogeneity was assessed using Cochrane’s Q, τ², and I² statistics. High heterogeneity was expected due to the diversity of abdominal surgical procedures, RSB administration protocols and comparators. A restricted maximum likelihood (REML) approach[24] was used to mitigate potential heterogeneity and was selected over other models due to its lower bias in estimating heterogeneity, better coverage of confidence intervals, and overall more reliable performance in typical clinical meta-analyses.[25,26] All analyses were performed using RevMan (version 7.2.0).[27] We considered an I² value <30%, 30–60%, 60–75% and 75–100% to represent low, moderate, substantial or considerable statistical heterogeneity, respectively.[28]

When a study had multiple intervention or comparator arms, they were separated prior to the random-effects meta-analysis to prevent unit-of-analysis errors.[29] The common arm was properly weighted between the study groups. Two studies had two arms for the RSB group, performed by either ultrasound or surgical guidance. Each RSB group was treated as a separate study. One study investigated different RSB dosing regimens (single, continuous, and repeated doses), which were analyzed as three separate studies. Three studies included more than one control arm: in two of these, the control groups consisted of a no-intervention arm and a local anesthetic arm; these were separated and analyzed as two separate studies. In the remaining study, two methods of local anesthetic administration were used, and these control arms were also analyzed separately, with the RSB group size divided between the two groups.

Two studies reported pain outcomes using the CHEOPS and QoR-40 pain assessments.[30,31] Since these measures do not quantify pain in comparable units to the other scales, they were analyzed separately in a sensitivity analysis for the 0–2 hour and 12–24 hour pain outcomes using SMDs.

To evaluate clinical significance, results were interpreted based on established minimal clinically important difference (MCID) thresholds. A reduction of 1.0 point on an 11-point NRS Likert Scale was deemed clinically meaningful.[32] A reduction of 5 mg IV morphine equivalents was also considered clinically meaningful.[33] MCID achievement was determined by comparing pooled and subgroup mean differences against the MCID threshold; clinical importance was confirmed only when the entire 95% CI exceeded the threshold.

Subgroup analyses were performed if n ≥ 3 to explore potential sources of heterogeneity and evaluate the efficacy of the RSB against comparator type: (1) sham block; (2) local anesthetic; (3) no intervention, RSB timing: (1) preoperative; (2) postoperative, RSB technique: (1) ultrasound-guided; (2) loss of resistance, Surgery type: (1) laparoscopic; (2) open.

Publication bias for all outcomes with at least ten studies was evaluated using a funnel plot and Egger’s regression intercept [Supplementary Figure S1.1 ^{(2MB, tif)} –1.4 ^{(2MB, tif)} , Supplementary Table 4].

Results

Study selection

Of the 910 articles identified in the database search, 31 articles[30,31,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61] were identified as eligible for inclusion in this review [Figure 1].

Figure 1.

PRISMA flowchart of the included studies. PRISMA, Preferred Reporting Items for Systematic Reviews and Meta-analyses

Study characteristics

Characteristics of the included RCTs are summarized in Table 1. 16 RCTs compared the RSB with no intervention,[31,34,40,42,43,45,47,49,50,52,53,54,57,58,60,61,62] while 10 compared RSB with local anesthesia,[30,35,36,37,38,39,42,46,51,52] and 6 with a sham block.[41,44,48,55,56,59] Eighteen out of 31 studies involved laparoscopic surgeries[34,35,39,40,42,43,44,46,47,50,52,55,56,58,60,61,62] and 13 involved open procedures.[30,31,36,37,38,41,45,48,49,51,54,57,59] Most studies (22/31) performed the RSB under ultrasound guidance[30,31,37,39,40,41,43,44,45,46,47,48,50,51,53,54,55,56,57,58,60,61] The RSB was administered postoperatively[30,35,36,37,38,41,43,44,46,49,51,52,53,55,57,58,59,62] in 18 studies and preoperatively[31,34,39,40,41,45,47,48,50,54,56,60,61] in the remaining 13.

Table 1.

Key characteristics of the 31 included studies

Study	Group Allocation	Surgical Procedure	Surgical Technique	RSB Technique	RSB Timing	RSB Drug	Control Intervention	Postoperative Analgesia
Smith et al., 1988[34]	RSB (22) Control (24)	Diagnostic gynecologic laparoscopy	Laparoscopic	Loss of resistance	Preoperative	Bupivacaine 0.25%, 30 mL	No intervention	Papaveretum
Azemati et al., 2005[35]	RSB (30), Control (61)	Elective diagnostic gynecologic surgery	Laparoscopic	Loss of resistance	Postoperative	Bupivacaine 0.25%, 10 mL	Intraperitoneal infiltration (1) Intraincisional infiltration (2)	Not described
Isaac et al., 2006[30]	RSB (7) Control (6)	Umbilical hernia repair	Open	Direct insertion	Postoperative	Bupivacaine 0.25%, 0.15 mL/kg	Local anesthetic	Morphine
Gurnaney et al., 2011[36]	RSB (26) Control (26)	Umbilical hernia repair	Open	Ultrasound-guided	Postoperative	Bupivacaine 0.25% adjusted for weight	Local anesthetic	Morphine Oxycodone
Dingeman et al., 2013[37]	RSB (27) Control (25)	Elective umbilical hernia repair	Open	Ultrasound-guided	Postoperative	Ropivacaine 0.20%, 0.5 ml/kg	Local anesthetic	Morphine sulfate Codeine phosphate Acetamiophen
Khorgami et al., 2013[38]	RSB (30) Control (30)	Elective midline laparotomy	Open	Direct vision	Postoperative	Bupivacaine 0.25%, 1 mL/cm of incision length through 2 catheters every 6 h for 48 h	Suprafascial infiltration	Morphine
Kasem et al., 2015[39]	RSB (23) Control (22)	Single-incision laparoscopic cholecystectomy	Laparoscopic	Ultrasound-guided	Preoperative	Bupivacaine, 0.5%, 20 mL	Local anesthetic	Morphine Lormoxicam
Hamill et al., 2015[40]	RSB (63) Control (67)	Appendectomy	Laparoscopic	Ultrasound-guided	Preoperative	Bupivacaine 0.25%, adjusted for weight	No intervention	Paracetamol NSAIDs
Bakshi et al., 2016[41]	RSB (36) Control (35)	Midline laparotomy for gynecological cancer	Open	Ultrasound-guided	Postoperative	Bupivacaine 0.25%, 40 mL (36 mL if 45–50 kg) every 6 hours for 48 hours	Sham block	Morphine Diclofeanc Acetaminophen
Gupta et al., 2016[42]	RSB (25) Control (50)	Cholecystectomy	Laparoscopic	Loss of resistance	Preoperative	Ropivacaine 0.25%, 30 mL	No intervention (1) Intraperitoneal instillation (2)	Tramadol
Kim et al., 2016[43]	RSB (19) Control (20)	Robotic cholecystectomy	Laparoscopic	Ultrasound-guided	Postoperative	Ropivacaine 0.365%, 10 mL	No intervention	Fentanyl
Chung et al., 2017[44]	RSB (50) Control (25)	Single-Port Laparoscopic surgery for benign tumor of fallopian tube or ovary	Laparoscopic	Ultrasound-guided (1) Surgically (2)	Postoperative	Ropivacaine 0.5%, 20 mL	Sham block	Fentanyl
Kartalov et al., 2017[45]	RSB (30) Control (30)	Elective umbilical hernia repair	Open	Ultrasound-guided	Preoperative	Bupivacaine 0.25%, 40 mL	No intervention	Morphine Paracetamol
Uchinami et al., 2017[46]	RSB (17) Control (17)	Laparoscopic extraperitoneal closure	Laparoscopic	Ultrasound-guided	Postoperative	Ropivacaine 0.375%, 0.4 mL/kg	Local anesthetic	Not described
Cho et al., 2018[47]	RSB (30) Control (30)	Extraperitoneal closure	Laparoscopic	Ultrasound-guided	Preoperative	Ropivacaine 0.25%, 30mL	No intervention	Fentanyl Ketorolac
Ibrahim et al., 2018[48]	RSB (25) Control (25)	Radical prostatectomy	Open	Ultrasound-guided	Preoperative	Bupivacaine 0.25%, 40 mL	Sham block	Morphine Ketorolac Paracetamol
Purdy et al., 2018[49]	RSB (45) Control (12)	Midline laparotomy	Open	Cather insertion  (1) Single dose  (2) Repeated dose  (3) Continuous infusion	Postoperative	Levobupivacaine 0.25%, 0.25 mg/mL	No intervention	Oxycodone Paracetamol
Kinjo et al., 2019[62]	RSB (107) Control (101)	Benign gynecologic laparoscopy	Laparoscopic	Laparoscopic	Postoperative	Ropivacaine 0.5%, 6 mL/kg	No intervention	Pentazocine Diclofenac, Loxoprofen
Shah et al., 2019[50]	RSB (30) Control (30)	Tubal ligation	Laparoscopic	Ultrasound-guided	Preoperative	Bupivacaine 0.25%, 40 mL	No intervention	Tramadol
Laguduva et al., 2022[51]	RSB (50) Control (50)	Midline laparotomy	Open	Ultrasound-guided	Postoperative	Bupivacaine 0.225%, 15 mL	Local infiltration	Morphine Paracetamol
Suragul et al., 2022[52]	RSB (52) Control (48)	Cholecystectomy	Laparoscopic	Direct insertion	Postoperative	Bupivacaine 0.50%, 5 mL	No intervention (1) Subcutaneous infiltration (2)	Morphine
Siripruekpong et al., 2022[53]	RSB (32) Control (34)	Tubal resection	Laparoscopic	Ultrasound-guided	Postoperative	Bupivacaine 0.25%, 10 mL	No intervention	Acetaminophen
Yörükoğlu et al., 2023[54]	RSB (30) Control (30)	Caesarian delivery	Open	Ultrasound-guided	Preoperative	Bupivacaine 0.25%, 20 mL	No intervention	Morphine
Shi et al., 2023[55]	RSB (30) Control (30)	Radical gastrectomy	Laparoscopic	Ultrasound-guided	Postoperative	Ropivacaine 0.40%, 50 mL	Sham block	Sufentanil Flurbiprofen axetil
Yang et al., 2023[56]	RSB (22) Control (22)	Elective colorectal surgery	Laparoscopic	Ultrasound-guided	Preoperative	Ropivacaine, 0.4%, 40–50 mL	Sham block	Sufentanil Flurbiprofen axetil
Abougabal et al., 2024[57]	RSB (24) Control (24)	Midline laparotomy	Open	Ultrasound-guided	Postoperative	Bupivacaine, 0.25% boluses	No intervention	Morphine Paracetamol
Cheng et al., 2024[31]	RSB (45) Control (45)	Elective transabdominal midline gynecological surgery	Open	Ultrasound-guided	Preoperative	Ropivacaine 0.4% 40 mL	No intervention	Sufentanil Flurbiprofen
Cosarcan et al., 2024[58]	RSB (31) Control (30)	Robot Assisted Radical Prostatectomy	Laparoscopic	Ultrasound-guided	Postoperative	Bupivacaine 0.25%, 20 mL	No intervention	Fentanyl Tramadol Morphine
Opincans et al., 2024[59]	RSB (30) Control (30)	Gastrectomy	Open	Catheter insertion	Postoperative	Bupivacaine, 0.125%, 270 mL at rate of 5 mL/hr for 54 hours	Sham block	Ketorolacum trometamolum Trimperidine hidrochloridum
Chen et al., 2025[60]	RSB (71) Control (68)	Umbilical hernia repair	Laparoscopic	Ultrasound-guided	Preoperative	Ropivacaine 0.25%, 20 mL	No intervention	Sufentanil
Altenburg et al., 2025[61]	RSB (17) Control (18)	Inguinal hernia repair	Laparoscopic	Ultrasound-guided	Preoperative	Ropivacaine 0.375%, 40 mL	No intervention	Oxycodone Metamizole

Pain scoring tools included: VAS, NRS, VNRS, Revised Faces Pain Scale, CHEOPS, Revised Bieri FACES Pain Scale, FACES Pain Rating Scale, FLACC Pain Score, Numerical Analogue Scale, and QoR-40 Pain Item.

Risk of bias in studies

Based on the Cochrane Risk of Bias assessment, 13 out of 32 RCTs were classified as having a low risk,[31,35,36,38,41,46,48,51,52,53,54,58,59] 12 out of 32 as “some concerns”[30,37,39,40,44,45,47,49,50,55,56,61] and 5 out of 32 as “high risk”[34,42,43,57,60] [Figure 2]. Supplementary Figure S2 ^{(777.2KB, tif)} summarizes the specific risk assessments for each study across the five domains. Risk assessment justifications are available in Supplementary Table S5.

Figure 2.

Pooled risk of bias assessment of the 31 included randomized controlled trials, performed using the Cochrane Risk of Bias 2.0 tool

Quantitative synthesis

Studies requiring SD imputation are included in Supplementary Table S6.

Postoperative pain scores at rest at 0–2, 10–12 and 12–24 hour

Figure 3 displays the forest plots of all included studies grouped by postoperative pain time point.

Figure 3.

Forest plot demonstrating overall RSB performance compared to control, (a) 0–2 hour, (b) 10–12 hour, and (c) 12–24 hour postoperatively. RSB = Rectus sheath block

A total of 19 RCTs were included for the analysis of postoperative pain at 0–2 hours. In total, 678 participants received RSB, and 811 received control interventions. Pooled analysis demonstrated a statistically significant reduction in pain scores favoring RSB (MD, −1.46, 95% CI, [ − 2.26 to − 0.66]; P < 0.001).

Subgroup analyses demonstrated reductions in pain with RSB across all comparator types, timing of administration, RSB technique, and surgical approach. There was no consistent evidence of significant subgroup differences.

Heterogeneity for the pooled analysis was considerable (I² = 99%, P < 0.001).

Sensitivity analysis using standardized mean differences, including one study reporting pain on a non-comparable scale, showed a similar direction of effect (SMD = −1.33, 95% CI = [−2.15 to − 0.51]; P = 0.001).

Compared to the pre-specified MCID threshold of one point, the pooled estimate exceeded this threshold. Subgroup estimates surpassed the MCID for comparisons with no intervention and for pre-operative, postoperative, ultrasound-guided, loss-of-resistance, and laparoscopic subgroups, while estimates for sham block, local anesthetic infiltration, and open surgery did not. Confidence intervals crossed the MCID boundary for the pooled estimates and all subgroup analyses except sham block.

A total of 19 RCTs were included for analysis of postoperative pain at 10–12 hours. In total, 788 participants received RSB and 884 received control interventions. Pooled analysis demonstrated a statistically significant reduction in pain scores favoring RSB (MD, −0.94, 95% CI, [ − 1.40 to − 0.48]; P < 0.001).

Subgroup analyses demonstrated consistent reductions in pain with RSB across comparator types, timing of administration, technique, and surgical approach, with no significant subgroup differences.

Heterogeneity in the pooled 10–12-hour analysis was considerable (I² = 97%, P < 0.001).

A total of 20 RCTs were included to analyses postoperative pain at 12–24 hours. Overall, 764 participants received RSB and 874 received control interventions. The pooled analysis showed a statistically significant reduction favoring RSB (MD, −0.65, 95% CI, [ − 1.07 to − 0.23]; P = 0.002). The pooled estimate did not surpass the prespecified MCID threshold of 1 point.

Subgroup analyses revealed smaller and less consistent pain reductions across different comparator types and clinical settings, with no significant differences between subgroups.

Heterogeneity for the pooled analysis was high (I² = 95%).

IV morphine milligram equivalent consumption at 24 hour postoperatively

A total of 13 RCTs were included for analysis of cumulative opioid use at 24 hours. 482 participants received RSB and 451 received control interventions. Pooled analysis showed a statistically significant reduction favoring RSB (MD, −7.40, 95% CI, [ − 11.86 to − 2.94]; P = 0.001). Compared to the prespecified MCID threshold of 5 mg IV morphine equivalents, the pooled estimate exceeded this threshold.

Subgroup analyses showed decreases in opioid use across comparator types and clinical contexts. Greater reductions were seen in open surgery compared to laparoscopic surgery, although no consistent differences appeared among other subgroups.

Heterogeneity for the pooled analysis was considerable (I² = 100%).

Details on subgroup analyses, secondary outcomes, and sensitivity analyses are available in the attached supplemental data file [Supplementary Figures S2.1 ^{(16.1MB, tif)} –2.13 ^{(16.1MB, tif)} , Figure S3 ^{(747.4KB, tif)} , Figures S4.1 ^{(4.3MB, tif)} –4.4 ^{(4.3MB, tif)} , Figures S5.1 ^{(2.3MB, tif)} –5.2 ^{(2.3MB, tif)} ].

Our overall findings are summarized in a GRADE summary of findings table [Table 2] and a SoF table [Table 3]. The certainty of evidence was rated as moderate for all pain outcomes and low for 24-hour opioid consumption. Downgrading resulted from inconsistency (I² ≥97% for all outcomes). Indirectness, imprecision, and publication bias were not contributing factors. While confidence in the magnitude of effect is limited, the direction of effect consistently favored RSB across outcomes.

Table 2.

Evidence profile table of rectus sheath block vs control for patients undergoing abdominal surgery. GRADE quality of evidence is reported only when at least three studies report an outcome

Certainty assessment							No of patients		Effect		Certainty	Importance
No of studies	Study design	Risk of bias	Inconsistency	Indirectness	Imprecision	Other considerations	RSB	Control	Relative (95% CI)	Absolute (95% CI)
Pain at rest 0–2 hour postoperatively, (assessed with: NRS score; Scale from: 0 to 10)
19	randomized trials	not serious	seriousa	not serious	not serious	none	685	817	-	MD 1.46 points lower (2.26 lower to 0.66 lower)	⨁⨁⨁◯ Moderatea
Pain at rest 10–12 hour postoperatively (assessed with: NRS score; Scale from: 0 to 10)
19	randomized trials	not serious	seriousb	not serious	not serious	none	788	884	-	MD 0.94 points lower (1.4 lower to 0.48 lower)	⨁⨁⨁◯ Moderateb
Pain at rest 12–24 hour postoperatively (assessed with: NRS score; Scale from: 0 to 10)
21	randomized trials	not serious	seriousc	not serious	not serious	none	764	874	-	mean 0.55 points lower (1 lower to 0.11 lower)	⨁⨁⨁◯ Moderatec
Total IV morphine milligram equivalent consumption 24 hour postoperatively (mg)
14	randomized trials	not serious	very seriousd	not serious	not serious	none	534	496	-	MD 7.4 mg lower (11.86 lower to 2.94 lower)	⨁⨁◯◯ Lowd

CI: confidence interval; MD: mean difference Explanations a. Downgraded 1 level for inconsistency due to considerable heterogeneity (I²=99%). b. Downgraded 1 level for inconsistency due to considerable heterogeneity (I²=97%). c. Downgraded 1 level for inconsistency due to considerable heterogeneity (I² = 97%). d. Downgraded 2 levels for inconsistency due to considerable heterogeneity (I²=100%) with widely differing effect estimates and minimal overlap of confidence intervals across studies

Table 3.

Summary of Findings (SoF) Table

Outcomes	RSB Mean Pain Score (SD)	Control Mean Pain Score (SD)	Mean difference [95% Confidence Interval]	Number of participants (studies)	Quality of certainty of the evidence (GRADE)	Comments
Pain at rest 0–2 hour postoperatively, assessed with VAS score: 0–10 (worst)	2.08 (2.20)	3.62 (2.57)	−1.46 [−2.22, −0.66]	1489 (19 studies)[34,35,36,37,39,42,44,45,46,47,50,51,52,53,54,55,56,58,60]	●●●○ Moderate	High heterogeneity; I² = 99%, P<0.001
Pain at rest 10–12 hour postoperatively, assessed with VAS score: 0–10 (worst)	1.89 (1.27)	2.83 (1.86)	−0.94 [−1.40, −0.48]	1672 (19 studies)[34,35,38,39,42,43,45,47,49,50,51,52,54,55,56,58,59,60,62]	●●●○ Moderate	High heterogeneity; I² = 97%, P<0.001
Pain at rest 12–24 hour postoperatively, assessed with VAS score: 0–10 (worst)	2.33 (1.95)	2.99 (2.05)	−0.65 [−1.07, −0.23]	1548 (20 studies)[34,38,39,40,42,44,45,47,48,49,51,52,53,54,55,56,57,58,59,61,62]	●●●○ Moderate	High heterogeneity; I² = 95%, P<0.001
Intravenous morphine-equivalent consumption, 24 h (mg)	7.98 (4.99)	15.35 (11.41)	−7.40 [−11.86, −2.94]	933 (14 studies)[38,39,41,43,44,47,48,51,52,53,54,57,58]	●●○○ Low	High heterogeneity; I² = 100%, P<0.001

Population: Patients undergoing abdominal surgery. Intervention: Rectus sheath block. Comparator: Control (no intervention, placebo block, or local infiltration, as defined in each trial). SD=standard deviation; VAS=visual analogue scale; GRADE (Grading of Recommendations, Assessment, Development and Evaluation): High certainty - very confident that the true effect is close to the estimate; Moderate certainty - true effect likely close to the estimate, but may be substantially different; Low certainty - true effect may be substantially different from the estimate; Very low certainty - very little confidence in the effect estimate.

Discussion

This systematic review and meta-analysis show that the RSB reduces postoperative pain, especially in the first 0–2-hour period, with consistent reductions in postoperative opioid use. The analgesic benefit remained noticeable at 10–12 hours, though to a lesser extent, and tended to decrease by 12–24 hour. Subgroup analyses by comparator indicated that the early analgesic effect of the RSB was observed across all comparator groups, although effect sizes varied.

The largest effect estimates occurred during the 0–2-hour period, with pooling of 19 trials showing a statistically significant reduction in pain scores, with point estimates surpassing the prespecified MCID threshold. There was a significant reduction in pain across all comparator groups, with statistical evidence of subgroup differences, supporting the presence of this early analgesic effect and emphasizing the RSB’s potential usefulness in the immediate post-operative period.

Subgroup analyses showed consistent analgesic benefit of RSB across timing, technique, and surgical approach, with no significant subgroup differences. Apparent differences in statistical significance likely reflect variability in precision rather than actual differences in effectiveness, supporting the use of RSB as an adjunct for early postoperative analgesia.

By 10–12 hour, the analgesic benefit persisted but was reduced in magnitude, consistent with the expected duration of action of commonly used long-acting local anesthetics.[63] The pooled analysis showed a statistically significant reduction in pain scores, indicating that RSB provides analgesic benefit extending into the intermediate postoperative period. However, the pooled effect estimate did not surpass the MCID threshold, suggesting a less pronounced clinical impact than in the immediate postoperative period. Subgroup analyses revealed consistent effects across different comparator types, timing of administration, RSB technique, and surgical approach, with no meaningful differences between subgroups. Overall, although the benefit was smaller compared to the early postoperative period, the direction of the effect remained consistent.

At 12–24 hour, the pooled effect favored the RSB and remained statistically significant, although the benefit was smaller than at earlier timepoints and did not exceed the prespecified MCID threshold. This reduction aligns with the expected diminishing pharmacological effect of the block and the considerable heterogeneity observed across studies. Although some individual subgroups showed statistically significant reductions, there was no evidence of differences between subgroup categories, indicating that comparator type, timing of administration, RSB technique, and surgical approach did not significantly influence treatment effect. While RSB is unlikely to offer substantial analgesic benefit beyond 12 hours, it may still provide modest postoperative relief as part of a multimodal analgesic strategy.

Twenty-four-hour intravenous morphine use was significantly lower with the RSB, with the overall effect surpassing the predefined threshold for clinical relevance. Analyses specific to the comparator showed a significant opioid-sparing benefit compared to local anesthetic infiltration, while comparisons with sham and no-intervention controls were in the same direction, but did not achieve statistical significance. The surgical approach significantly influenced the treatment effect, with greater reductions seen in open surgery compared to laparoscopic procedures, indicating that the procedural context may affect the extent of the opioid-sparing benefit. These results support a clinically important role for RSB as part of multimodal analgesia, although the effect size varies across different clinical settings.

These findings expand upon our previous work,[12] which demonstrated significant early analgesic benefit as well as a statistically significant reduction in 24-hour opioid consumption. The present findings are also broadly aligned with the findings of other recent syntheses,[2,10] where continuous RSB was identified as one of the most effective non-neuraxial techniques for reducing 24-hour opioid requirements and resting pain after midline laparotomy, as well as reductions in early pain scores and opioid use following laparoscopic surgery. Pediatric evidence similarly supports the efficacy of the RSB in umbilical hernia repair.[11]

While previous meta-analyses offer valuable insights within their respective clinical contexts, their narrow inclusion criteria and limited data presentation restrict generalizability and impede comparator-specific interpretation. In contrast, the strength of this review lies in its breadth and analytical depth: by including 31 RCTs covering both laparoscopic and open abdominal surgeries, adults and pediatrics, and by presenting several subgroup analyses, this review provides the most comprehensive assessment of RSB efficacy to date. This wider and more diverse evidence base allows for a more clinically meaningful description of the RSB’s analgesic profile.

A key limitation of this review is the extremely high heterogeneity seen across almost all pooled outcomes. In our analysis, I² values often exceeded 80–90%, indicating significant variability between studies. This level of heterogeneity was expected due to the diversity of abdominal procedures, RSB techniques, local anesthetic regimens, and perioperative analgesic approaches across trials, aligning with heterogeneity patterns reported in other meta-analyses of peripheral nerve blocks.[10,11,64] Because trials reported pain scores at different timepoints within our predefined postoperative windows, some outcome heterogeneity was introduced despite standardizing intervals, which may have diminished the precision of pooled estimates. Although our analyses showed substantial statistical heterogeneity, this should not be interpreted as a sign of poor methodological quality. As highlighted in previous meta-epidemiological studies in anesthesiology, high I² values often emerge in reviews combining numerous small, randomized trials that vary in patient populations, surgical contexts, interventions, and outcome measurement methods. Such clinical and methodological differences can lead to marked variability in effect estimates even when individual trials are well designed. In this context, high I² values are more likely to reflect genuine differences between studies rather than bias or errors.[65] Although our sample sizes were limited, the consistent trend of analgesic benefit from RSB across all postoperative intervals enhances our confidence in the effect estimate. For these reasons, we believe that although the GRADE framework rightly downgrades the evidence, it may underestimate the overall strength, plausibility, and clinical importance of our findings.

This review underscores several key priorities for future research. First, there is a clear need for comparative studies assessing the analgesic performance of the RSB against other increasingly popular abdominal wall blocks, such as the quadratus lumborum, erector spinae plane, ilioinguinal-iliohypogastric, and transversalis fascia plane blocks. Clarifying how the RSB compares with these newer techniques would meaningfully inform clinical practice. Second, future trials should aim for more standardized time points when measuring postoperative pain scores. Current studies often rely on broad or inconsistent postoperative windows, which hinder our ability to accurately determine the true duration and trajectory of block efficacy. Finally, once sufficient evidence has been gathered, further investigation into how different approaches to administering the RSB compare regarding success rate, analgesic effectiveness, and safety will be essential. Establishing these practice-level differences will assist in optimizing technique selection and enhancing patient care.

In summary, our findings show that the RSB offers clinically relevant early postoperative analgesia and decreases postoperative opioid use, with the strongest effect seen in the 0–2-hour period and diminishing afterward. Although substantial heterogeneity limits the certainty of these results, the overall evidence supports the RSB as a useful part of multimodal analgesia for abdominal surgery. Further research should identify the best technique, timing, and how it compares to other abdominal wall blocks.

Author contributions

ELR: Data curation; Formal analysis; Investigation; Methodology; Validation; Visualization; Writing-original draft.

SDJ: Methodology; Project administration; Supervision.

RH: Methodology; Project administration; Supervision.

TMH: Conceptualization; Methodology; Project administration; Supervision; Writing, review, and editing.

AS: review.

Declaration of Generative AI and AI-assisted technologies in the writing process

During the preparation of this work, the authors used ChatGPT (OpenAI) to improve clarity and organization in the writing. After using this tool, the authors reviewed and edited the content as needed and take full responsibility for the content of the publication.

Conflicts of interest

TMH and RH are Shareholders of DivoccoAI, Montreal, Canada.

Data availability statement

Study data can be made available upon request to the corresponding author.

Supplementary Figure S1

Assessment of publication bias

Supplementary Figure S2

Risk of bias assessment

Supplementary Figure 2

Forest Plots demonstrating subgroup postoperative pain outcomes for RSB vs Control

Supplementary Figure 3

Forest Plots demonstrating overall RSB performance compared to control for Intravenous morphine milligram equivalent consumption in 24h.

Supplementary Figure 4

Forest Plots demonstrating subgroup intravenous morphine milligram equivalent consumption in 24h for RSB vs Control

Supplementary Figure 5

Forest Plots demonstrating sensitivity analyses of outcomes for RSB vs Control S5.1 0-2h postoperative pain

Supplementary Materials

Supplementary Table S1.

Prisma Checklist

Section and Topic	Item #	Checklist item	Location where item is reported
TITLE
Title	1	Identify the report as a systematic review.	Page 1
ABSTRACT
Abstract	2	See the PRISMA 2020 for Abstracts checklist.	Page 2
INTRODUCTION
Rationale	3	Describe the rationale for the review in the context of existing knowledge.	Page 3
Objectives	4	Provide an explicit statement of the objective(s) or question(s) the review addresses.	Page 3
METHODS
Eligibility criteria	5	Specify the inclusion and exclusion criteria for the review and how studies were grouped for the syntheses.	Page 4
Information sources	6	Specify all databases, registers, websites, organisations, reference lists and other sources searched or consulted to identify studies. Specify the date when each source was last searched or consulted.	Page 4
Search strategy	7	Present the full search strategies for all databases, registers and websites, including any filters and limits used.	Page 4
Selection process	8	Specify the methods used to decide whether a study met the inclusion criteria of the review, including how many reviewers screened each record and each report retrieved, whether they worked independently, and if applicable, details of automation tools used in the process.	Page 4
Data collection process	9	Specify the methods used to collect data from reports, including how many reviewers collected data from each report, whether they worked independently, any processes for obtaining or confirming data from study investigators, and if applicable, details of automation tools used in the process.	Page 4-5
Data items	10a	List and define all outcomes for which data were sought. Specify whether all results that were compatible with each outcome domain in each study were sought (e.g. for all measures, time points, analyses), and if not, the methods used to decide which results to collect.	Pag 4-5
	10b	List and define all other variables for which data were sought (e.g. participant and intervention characteristics, funding sources). Describe any assumptions made about any missing or unclear information.	Page 5
Study risk of bias assessment	11	Specify the methods used to assess risk of bias in the included studies, including details of the tool(s) used, how many reviewers assessed each study and whether they worked independently, and if applicable, details of automation tools used in the process.	Page 5
Effect measures	12	Specify for each outcome the effect measure(s) (e.g. risk ratio, mean difference) used in the synthesis or presentation of results.	Page 5
Synthesis methods	13a	Describe the processes used to decide which studies were eligible for each synthesis (e.g. tabulating the study intervention characteristics and comparing against the planned groups for each synthesis (item #5)).	Page 5-6
	13b	Describe any methods required to prepare the data for presentation or synthesis, such as handling of missing summary statistics, or data conversions.	Page 5
	13c	Describe any methods used to tabulate or visually display results of individual studies and syntheses.	Page 5
	13d	Describe any methods used to synthesize results and provide a rationale for the choice(s). If meta-analysis was performed, describe the model(s), method(s) to identify the presence and extent of statistical heterogeneity, and software package(s) used.	Page 5-6
	13e	Describe any methods used to explore possible causes of heterogeneity among study results (e.g. subgroup analysis, meta-regression).	Page 6
	13f	Describe any sensitivity analyses conducted to assess robustness of the synthesized results.	Page 6
Reporting bias assessment	14	Describe any methods used to assess risk of bias due to missing results in a synthesis (arising from reporting biases).	Page 5-6
Certainty assessment	15	Describe any methods used to assess certainty (or confidence) in the body of evidence for an outcome.	Page 5
RESULTS
Study selection	16a	Describe the results of the search and selection process, from the number of records identified in the search to the number of studies included in the review, ideally using a flow diagram.	Page 4
	16b	Cite studies that might appear to meet the inclusion criteria, but which were excluded, and explain why they were excluded.	Page 4
Study characteristics	17	Cite each included study and present its characteristics.	Page 19-20
Risk of bias in studies	18	Present assessments of risk of bias for each included study.	Page 7
Results of individual studies	19	For all outcomes, present, for each study: (a) summary statistics for each group (where appropriate) and (b) an effect estimate and its precision (e.g. confidence/credible interval), ideally using structured tables or plots.	Figure 3, Figure S2-5
Results of syntheses	20a	For each synthesis, briefly summarise the characteristics and risk of bias among contributing studies.	Page 7
	20b	Present results of all statistical syntheses conducted. If meta-analysis was done, present for each the summary estimate and its precision (e.g. confidence/credible interval) and measures of statistical heterogeneity. If comparing groups, describe the direction of the effect.	Page 7-9
	20c	Present results of all investigations of possible causes of heterogeneity among study results.	Page 7-9
	20d	Present results of all sensitivity analyses conducted to assess the robustness of the synthesized results.	Page 7-9
Reporting biases	21	Present assessments of risk of bias due to missing results (arising from reporting biases) for each synthesis assessed.	N/A
Certainty of evidence	22	Present assessments of certainty (or confidence) in the body of evidence for each outcome assessed.	Page 5, 21-22
DISCUSSION
Discussion	23 a	Provide a general interpretation of the results in the context of other evidence.	Page 10
	23b	Discuss any limitations of the evidence included in the review.	Page 11
	23c	Discuss any limitations of the review processes used.	Page 11
	23d	Discuss implications of the results for practice, policy, and future research.	Page 12
OTHER INFORMATION
Registration and protocol	24a	Provide registration information for the review, including register name and registration number, or state that the review was not registered.	Page 2
	24b	Indicate where the review protocol can be accessed, or state that a protocol was not prepared.	Page 2
	24c	Describe and explain any amendments to information provided at registration or in the protocol.	N/A
Support	25	Describe sources of financial or non-financial support for the review, and the role of the funders or sponsors in the review.	Page 13
Competing interests	26	Declare any competing interests of review authors.	Page 13
Availability of data, code and other materials	27	Report which of the following are publicly available and where they can be found: template data collection forms; data extracted from included studies; data used for all analyses; analytic code; any other materials used in the review.	Page 13

Supplementary Table S2.

Search strategy

PubMed:

Search number	Query	Sort By	Filters	Search Details	Results
3	#1 AND #2		Randomized Controlled Trial	(("rectus sheath block"[Title/Abstract] OR "rectus sheath blocks"[Title/Abstract] OR "rectus abdominis sheath block"[Title/Abstract] OR "rectus sheath catheter"[Title/Abstract] OR "RSB"[Title/Abstract] OR ("rectus abdominis"[Title/Abstract] AND "block*"[Title/Abstract])) AND "randomized controlled trial"[Publication Type] AND (("abdomen/surgery"[MeSH Terms] OR "Laparotomy"[MeSH Terms] OR "Laparoscopy"[MeSH Terms] OR "abdominal surg*"[Title/Abstract] OR "laparotom*"[Title/Abstract] OR "laparoscop*"[Title/Abstract] OR "midline laparotomy"[Title/Abstract] OR "midline incision"[Title/Abstract]) AND "randomized controlled trial"[Publication Type])) AND (randomizedcontrolledtrial[Filter])	63
1	("rectus sheath block"[tiab] OR "rectus sheath blocks"[tiab] OR "rectus abdominis sheath block"[tiab] OR "rectus sheath catheter"[tiab] OR RSB[tiab] OR ("rectus abdominis"[tiab] AND block*[tiab]))		Randomized Controlled Trial	("rectus sheath block"[Title/Abstract] OR "rectus sheath blocks"[Title/Abstract] OR "rectus abdominis sheath block"[Title/Abstract] OR "rectus sheath catheter"[Title/Abstract] OR "RSB"[Title/Abstract] OR ("rectus abdominis"[Title/Abstract] AND "block*"[Title/Abstract])) AND (randomizedcontrolledtrial[Filter])	119
2	("Abdomen/surgery"[Mesh] OR "Laparotomy"[Mesh] OR "Laparoscopy"[Mesh] OR abdominal surg*[tiab] OR laparotom*[tiab] OR		Randomized Controlled Trial	("abdomen/surgery"[MeSH Terms] OR "Laparotomy"[MeSH Terms] OR "Laparoscopy"[MeSH Terms] OR "abdominal surg*"[Title/Abstract] OR	12,047
	laparoscop*[tiab] OR "midline laparotomy"[tiab] OR "midline incision"[tiab])			"laparotom*"[Title/Abstract] OR "laparoscop*"[Title/Abstract] OR "midline laparotomy"[Title/Abstract] OR "midline incision"[Title/Abstract]) AND (randomizedcontrolledtrial[Filter])

____________________________________________________________________________________

Embase Classic+Embase <1947 to 2025 Week 44>

1 rectus sheath block/ 134

2 (rectus sheath block or rectus sheath blocks or rectus abdominis sheath block or rectus sheath catheter or RSB).ti,ab. 1618

3 1 or 2 1667

4 exp abdominal surgery/ 1192420

5 exp laparotomy/ 121142

6 exp laparoscopy/ 248120

7 (abdominal surg* or laparotom* or laparoscop* or midline laparotomy or midline incision).ti,ab. 390364

8 4 or 5 or 6 or 7 1267316

9 randomized controlled trial/ 1144044

10 controlled clinical trial/ 461759

11 (random* or placebo* or trial).ti,ab. 3404882

12 9 or 10 or 11 3651646

13 3 and 8 and 12 244

14 limit 13 to (human and english language) 234

____________________________________________________________________________________

Web of science:

# Web of Science Search Strategy (v0.1)

# Database: Web of Science Core Collection

# Entitlements:

- WOS.IC: 1993 to 2025

- WOS.CCR: 1985 to 2025

- WOS.SCI: 1900 to 2025

- WOS.AHCI: 1975 to 2025

- WOS.BHCI: 2005 to 2025

- WOS.BSCI: 2005 to 2025

- WOS.ESCI: 2005 to 2025

- WOS.ISTP: 1990 to 2025

- WOS.SSCI: 1900 to 2025

- WOS.ISSHP: 1990 to 2025

# Searches:

1: TS=("rectus sheath block"

OR "rectus sheath blocks"

OR "rectus abdominis sheath block"

OR "rectus sheath catheter")

AND

TS=(laparotomy

OR laparoscopy

OR "abdominal surgery"

OR "midline incision")

AND

TS=(randomized

OR randomised

OR "randomized controlled trial"

OR "randomised controlled trial"

OR placebo

OR "clinical trial") Date Run: Mon Oct 27 2025 19:03:04 GMT-0500 (Eastern

Standard Time) Results: 61

____________________________________________________________________________________

Scopus:

TITLE-ABS-KEY ( “rectus sheath block” OR “rectus sheath blocks” OR “rectus abdominis sheath block” OR “rectus sheath catheter” OR RSB ) AND TITLE-ABS-KEY ( laparotomy OR laparoscopy OR “abdominal surgery” OR “midline incision” ) AND TITLE-ABS-KEY ( randomized OR randomised OR “randomized controlled trial” OR “randomised controlled trial” OR placebo OR “clinical trial” ) AND ( LIMIT-TO ( EXACTKEYWORD , “Human” ) OR LIMIT-TO ( EXACTKEYWORD , “Rectus Sheath Block” ) OR LIMIT-TO ( EXACTKEYWORD , “Randomized Controlled Trial” ) )

Results: 92

Supplementary Table S3.

Reasons for reports excluded from the review

	Study	Reason for exclusion
1	Abo-Zeid MA, Al-Refaey AK, Zeina AM. Surgically-assisted abdominal wall blocks for analgesia after abdominoplasty: a prospective randomized trial. Saudi J Anaesth. 2018;12(4):593-598. doi:10.4103/sja.SJA_303_18	Control n=1
2	Bhatia K, Columb M, Wadsworth R, Macnab W, Jepegnanam C, Campbell T, Van Dellen D. Effect of rectus sheath block vs spinal anaesthesia on time-to-readiness for hospital discharge after trans-peritoneal hand-assisted laparoscopic live donor nephrectomy: a randomised trial. Eur J Anaesthesiol. 2021;38(4):374-382. doi:10.1097/EJA.0000000000001337	Control: spinal anesthesia
3	Bulun Yediyildiz M, Yilmaz Ak H, Durmuş İ, et al. Efficacy of ultrasound-guided bilateral rectus sheath block vs. local anesthetic infiltration in gynecologic oncology patients undergoing midline laparotomy: a triple-blinded randomized controlled trial. Minerva Anestesiol. 2025;91(3):147-154. doi:10.23736/S0375-9393.24.18302-2	Pain not measured explicitly at rest
4	Chen L, Liu S, Cao Y, Yan L, Shen Y. Rectus sheath block versus local anesthetic infiltration in pediatric laparoscopic inguinal hernia repair: a randomized controlled trial. Int J Surg. 2023;109(4):716-722. doi:10.1097/JS9.0000000000000265	Cumulative 24hour opioid consumption not recorded
5	Choi BJ, Choi SG, Ryeon O, Kwon W. A study of the analgesic efficacy of rectus sheath block in single-port total laparoscopic hysterectomy: a randomized controlled study. Journal of International Medical Research. 2022;50(10). doi:10.1177/03000605221133061	Pain not measured explicitly at rest
6	Cowlishaw PJ, Kotze PJ, Gleeson L, Chetty N, Stanbury LE, Harms PJ. Randomised Comparison of Three Types of Continuous Anterior Abdominal Wall Block after Midline Laparotomy for Gynaecological Oncology Surgery. Anaesthesia and Intensive Care. 2017;45(4):453-458. doi:10.1177/0310057X1704500407	Patients received spinal anesthesia
7	Dowidar AERM, Ezz HAA, Shama AAE, Eloraby MA. Postoperative analgesia of ultrasound guided rectus sheath catheters versus continuous wound catheters for colorectal surgery: a randomized clinical trial. Egypt J Anaesth. 2016;32(3):375-383. doi:10.1016/j.egja.2016.02.001	Control: continuous wound catheter infusion
8	Flack SH, Martin LD, Walker BJ, et al. Ultrasound-guided rectus sheath block or wound infiltration in children: a randomized blinded study of analgesia and bupivacaine absorption. Paediatr Anaesth. 2014;24(9):968-973. doi:10.1111/pan.12438	Pain not measured explicitly at rest, Cumulative 24hour opioid consumption not recorded
9	Güleç E, et al. Ultrasound guided rectus sheath block vs intravenous tramadol on postoperative analgesia in children undergoing inguinal hernia repair. Cukurova Med J. 2017;42(3):459-464. doi:10.17826/cutf.296419	Pain not measured explicitly at rest
10	Hong S, Kim H, Park J. Analgesic effectiveness of rectus sheath block during open gastrectomy: A prospective double-blinded randomized controlled clinical trial. Medicine (Baltimore). 2019;98(15):e15159. doi:10.1097/MD.0000000000015159	Quantity of IV-PCA fentanyl received not provided
11	Ibrahim, M., El Shamaa, H., & Ads, E. (2016). Efficacy of combined ultrasound guided anterior and posterior rectus sheath block for postoperative analgesia following umbilical hernia repair: Randomized, controlled trial. Egyptian Journal of Anaesthesia, 32(4), 519–526. https://doi-org.proxy3.library.mcgill.ca/10.1016/j.egja.2016.10.009	Wrong intervention: Posterior RSB, Anterior + Posterior RSB
12	Irum S, Saleem S, Bano A, Irum S, Fatima K. Assessment of postoperative analgesic effect of rectus sheath block in gynecological laparoscopic surgery. J Ayub Med Coll Abbottabad. 2024;36(3):621-624.	Pain not measured explicitly at rest
13	Kamei, H., Ishibashi, N., Nakayama, G., Hamada, N., Ogata, Y., & Akagi, Y. (2015). Ultrasound-guided rectus sheath block for single-incision laparoscopic cholecystectomy. Asian journal of endoscopic surgery, 8(2), 148–152. https://doi-org.proxy3.library.mcgill.ca/10.1111/ases.12178x	Pain not measured explicitly at rest
14	Kärkkäinen J, Selander T, Purdy M, Juvonen P, Eskelinen M. Patients with Increased Levels of the Oxidative Stress Biomarker SOD1 Appear to Have Diminished Postoperative Pain After Midline Laparotomy: A Randomised Trial with Special Reference to Postoperative Pain Score (NRS). Anticancer Res. 2018;38(2):1003-1008. doi:10.21873/anticanres.12315	No postoperative pain outcome
15	Kauffman JD, Nguyen ATH, Litz CN, et al. Laparoscopic-guided versus transincisional rectus sheath block for pediatric single-incision laparoscopic cholecystectomy: A randomized controlled trial. J Pediatr Surg. 2020;55(8):1436-1443. doi:10.1016/j.jpedsurg.2020.03.002	Wrong control: Transincisional versus laparoscopic guided RSB
16	Kitamura N, Iida H, Maehira H, et al. Postoperative analgesic effect of ultrasound-guided rectus sheath block and local anesthetic infiltration after laparoscopic cholecystectomy: Results of a prospective randomized controlled trial. Asian J Endosc Surg. 2022;15(1):29-35. doi:10.1111/ases.12957	Pain not measured explicitly at rest
17	Kuniyoshi H, Yamamoto Y, Kimura S, Hiroe T, Terui T, Kase Y. Comparison of the analgesic effects continuous epidural anesthesia and continuous rectus sheath block in patients undergoing gynecological cancer surgery: a non-inferiority randomized control trial. J Anesth. 2021;35(5):663-670. doi:10.1007/s00540-021-02973-1	Wrong control: Epidural
18	Kuosmanen V, Ruottinen M, Rahkola D, et al. Brief Pain Inventory (BPI) Health Survey After Midline Laparotomy With the Rectus Sheath Block (RSB) Analgesia: A Randomised Trial of Patients With Cancer and Benign Disease. Anticancer Res. 2019;39(12):6751-6757. doi:10.21873/anticanres.13890	Pain not measured explicitly at rest
19	Kuppuvelumani P, Jaradi H, Delilkan A. Abdominal nerve blockade for postoperative analgesia after caesarean section. Asia Oceania J Obstet Gynaecol. 1993;19(2):165-169. doi:10.1111/j.1447-0756.1993.tb00368.x	Wrong intervention: No rectus sheath block group
20	Litz CN, Farach SM, Fernandez AM, et al. Percutaneous ultrasound-guided vs. intraoperative rectus sheath block for pediatric umbilical hernia repair: A randomized clinical trial. J Pediatr Surg. 2017;52(6):901-906. doi:10.1016/j.jpedsurg.2017.03.007	Wrong control: Intraoperative RSB vs Ultrasound-guided RSB
21	Liu T, Tuo J, Wei Q, et al. Effects of Abdominal Wall Blocks on Postoperative Delirium in Elderly Patients Undergoing Laparoscopic Surgery: A Randomized Controlled Study. Med Sci Monit. 2022;28:e934281. Published 2022 Mar 14. doi:10.12659/MSM.934281	Wrong intervention: Combined block
22	Li Y, Jiang X, Wang J, et al. Intravenous Dexmedetomidine Combined with Ultrasound-Guided Rectus Sheath Block for Open Gastrectomy: a Prospective Randomized Trial. J Gastrointest Surg. 2020;24(6):1290-1297. doi:10.1007/s11605-019-04249-2	Insufficient outcome: Only moderate and severe pain scores at rest recorded.
23	Lui MW, Li TKT, Lui F, Ong CYT. A randomised, controlled trial of rectus sheath bupivacaine and intrathecal bupivacaine, without or with intrathecal morphine, vs. intrathecal bupivacaine and morphine after caesarean section. Anaesthesia. 2017;72(10):1225-1229. doi:10.1111/anae.13998	All patients received intrathecal anesthesia
24	Opincans J, Ivanovs I, Miscuks A, et al. Comparison of Bilateral Rectus Sheath Block and Thoracic Epidural Analgesia for Postoperative Pain Control After Open Gastrectomy: A Randomized Controlled Trial. Medicina (Kaunas). 2025;61(9):1695. Published 2025 Sep 18. doi:10.3390/medicina61091695	Wrong control: Thoracic epidural analgesia Wrong outcomes
25	Relland LM, Tobias JD, Martin D, et al. Ultrasound-guided rectus sheath block, caudal analgesia, or surgical site infiltration for pediatric umbilical herniorrhaphy: a prospective, double-blinded, randomized comparison of three regional anesthetic techniques. J Pain Res. 2017;10:2629-2634. Published 2017 Nov 9. doi:10.2147/JPR.S144259	Pain not measured explicitly at rest
26	Shim JW, Cho YJ, Kim M, et al. Comparison of analgesic efficacy between rectus sheath blockade, intrathecal morphine with bupivacaine, and intravenous patient-controlled analgesia in patients undergoing robot-assisted laparoscopic prostatectomy: a prospective, observational clinical study. BMC Anesthesiol. 2020;20(1):291. Published 2020 Nov 23. doi:10.1186/s12871-020-01208-2	Opioid received not expressed in mg, cumulative IV-PCA infusion with a combination of agents expressed in mL without specification of quantity of opioid
27	Tamura T, Kaneko K, Yokota S, et al. Comparison between rectus sheath block with 0.25% ropivacaine and local anesthetic infiltration with 0.5% ropivacaine for laparoscopic inguinal hernia repair in children. Nagoya J Med Sci. 2019;81(3):341-349. doi:10.18999/nagjms.81.3.341	Outcome data provided in least square means, control and intervention group receiving different concentrations of local anesthetic.
28	Wang Y, Li M, Wang Z, Liu W. Use of Bilateral Rectus Sheath Blocks in Open Umbilical Hernia Repair. Pain Physician. 2024;27(2):E239-E244.	Non-controlled trial, pain scores at rest not meeting predefined ranges
29	Yang N, Tao QY, Niu JY, et al. Effect of a local anesthetic injection kit on pain relief and postoperative recovery after transumbilical single-incision laparoscopic cholecystectomy. J Pain Res. 2023;16:2791-2801. doi:10.2147/JPR.S422454	Pain not measured explicitly at rest
30	Zhu S, Da X, Wang J, et al. Application of incision-based precision multipoint rectus sheath block and bilateral rectus sheath block in laparoscopic-assisted colorectal surgery: a randomized, controlled trial. Postgrad Med J. Published online September 30, 2025. doi:10.1093/postmj/qgaf166	Wrong control: comparison of two RSB techniques

Supplementary Table S4.

Publication bias assessment

Outcome	Egger’s regression intercept	P value
Pain at rest 0-2 h postoperatively	0.559	0.576
Pain at rest 10-12h postoperatively	-0.155	0.877
Pain at rest 12-24h postoperatively	0.262	0.793
Total morphine milligram equivalent consumption at 24h postoperatively	-0.880	0.379

Supplementary Table 6.

Studies requiring standard deviation imputation

Outcome	Imputed SD	Studies
0-2h postoperative pain at rest	0.75	(45, 50, 55, 56)
10-12h postoperative pain at rest	0.74	(50, 51, 55, 56, 62)
12-24h postoperative pain at rest	1.04	(45, 56, 58)

Funding Statement

Nil.