Is transversus abdominis plane block universally effective after cesarean delivery? A systematic review and meta-analysis

Introduction

Cesarean delivery now accounts for roughly 21% of births worldwide, a figure expected to climb toward 30% by 2030 (1). Adequate analgesia after the procedure is not merely a comfort issue. Poorly managed pain delays recovery, interferes with newborn care, raises the risk of thromboembolism, and substantially increases rates of chronic postpartum pain and depression (2). Whether the analgesic benefits attributed to the TAP block in general abdominal surgery translate cleanly to the cesarean setting is a different question, however. Most patients undergoing cesarean section receive neuraxial anesthesia before the incision, and that pre-existing analgesic coverage changes the equation in ways that findings from other surgical populations cannot capture.

Over the past two decades the TAP block has become a fixture of opioid-sparing multimodal analgesia across a wide range of abdominal procedures. Real-time ultrasound guidance made the technique safer and more reproducible (3), and the resulting track record has earned it a formal recommendation in enhanced recovery protocols—most recently in the joint colorectal surgery guidelines of the American Society of Colon and Rectal Surgeons and the Society of American Gastrointestinal and Endoscopic Surgeons (4). Evidence in gynecologic surgery specifically has continued to grow: a recent systematic review and meta-analysis of randomized trials comparing TAP block with wound infiltration in gynecologic procedures found that TAP block reduces early postoperative pain in laparoscopic surgery (6), further supporting its role across the abdominopelvic spectrum. Broader meta-analyses covering colorectal, bariatric, and gynecological surgery have each documented meaningful reductions in pain and opioid use (5).

Intrathecal morphine (ITM) remains the reference standard for post-cesarean pain control, providing sustained analgesia at the spinal level for 12–24 h. That advantage comes with well-known drawbacks such as pruritus, nausea, urinary retention, and the rare but serious risk of delayed respiratory depression, and it is not universally available. When neuraxial anesthesia is contraindicated by coagulopathy, urgent fetal compromise, or patient refusal, general anesthesia becomes necessary, and preservative-free morphine is not stocked in every institution worldwide.

The TAP block targets thoracolumbar nerves T6–L1 as they traverse the fascial plane between the internal oblique and transversus abdominis muscles, producing somatic analgesia across the anterior abdominal wall. McDonnell et al. introduced the landmark technique in 2007 and ultrasound guidance followed shortly after, markedly improving precision and reliability (6, 7). Early meta-analyses by Abdallah et al. and Mishriky et al. found a meaningful opioid-sparing signal (8, 9), but these syntheses were conducted before ITM was routinely co-administered with spinal anesthesia and before ultrasound-guided technique was ubiquitous. When investigators began testing the block against more contemporary analgesic backgrounds, results grew inconsistent: multiple well-designed RCTs found no meaningful added benefit when TAP block was superimposed on an ITM-inclusive spinal protocol (10, 11). Outcomes appear to depend on the anesthetic technique used, whether neuraxial opioids are on board, the specific block approach, and the composition of the background analgesic regimen.

What the literature still lacks is a synthesis that evaluates TAP block effectiveness across the distinct clinical environments in which cesarean delivery is performed. The primary objective of this systematic review and meta-analysis was precisely defined a priori: to evaluate the effect of TAP block on 24 h postoperative opioid consumption following cesarean delivery. Anesthetic technique (general vs. spinal anesthesia) and concomitant intrathecal morphine use were pre-specified as the primary subgroup variables before data extraction, selected based on biological plausibility as effect modifiers. The identification of heterogeneity across these subgroups reflects pre-planned analytical structure, not post-hoc inference.

Methods

This review follows PRISMA 2020 reporting guidelines. A protocol was registered prospectively in PROSPERO (registration number: 1373002).

Search strategy

A systematic literature search was conducted in PubMed/MEDLINE, Embase, and the Cochrane Central Register of Controlled Trials (CENTRAL) from database inception through March 2024, with no language restrictions. The complete search strings for each database are provided in Supplementary Appendix A. Briefly, terms combined MeSH headings and free-text keywords for the intervention (“transversus abdominis plane block,” “TAP block,” “fascial plane block”), the population (“cesarean delivery,” “cesarean section,” “caesarean”), and outcomes (“postoperative pain,” “opioid consumption,” “analgesia”). No filters were applied for study design, language, or publication status. Reference lists of all included studies and relevant systematic reviews were manually screened. Clinical trial registries (ClinicalTrials.gov and WHO ICTRP) were searched for ongoing or unpublished studies using the same keywords.

Eligibility criteria

Eligibility was defined prospectively using a PICO framework. A study qualified if it satisfied all four of the following criteria: Two rules governed active comparators. Studies were excluded if the sole comparator was a fascial plane or neuraxial regional block (e.g., quadratus lumborum block, erector spinae plane block) and no placebo or standard-care arm was present; this design cannot isolate the independent contribution of TAP block. Studies comparing TAP block with wound infiltration were eligible regardless of whether a no-block arm was included, because wound infiltration is a non-equivalent, non-fascial-plane technique that constitutes a clinically meaningful comparator. Studies incorporating both an active regional comparator and a sham or standard-care control arm were also eligible. These rules were prospectively registered in the PROSPERO protocol. Also excluded: studies using TAP block for intraoperative anesthesia rather than postoperative analgesia; those with no postoperative pain outcome; and duplicate publications.

• Population: Adult patients (≥18 years) undergoing elective or non-elective cesarean delivery under any anesthetic technique.
• Intervention: TAP block performed by any approach (lateral, subcostal, posterior, or landmark technique) using any local anesthetic agent or formulation, including liposomal bupivacaine.
• Comparator: Placebo injection, no block, standard systemic analgesia, or active comparator (wound infiltration, quadratus lumborum block, or transversalis fascia plane block).
• Outcomes: At least one postoperative analgesic outcome reported, including opioid consumption, pain scores (NRS or VAS), time to first analgesic request, or patient-reported outcomes.
• Study design: Randomized controlled trials (RCTs), quasi-randomized trials, and comparative observational studies (prospective or retrospective cohort studies with or without propensity score matching) were eligible. Observational studies were included to maximize evidence in clinical contexts where randomized data are limited (general anesthesia, extended-duration local anesthetic formulations). Observational studies contributed to qualitative synthesis only and were not incorporated into the quantitative meta-analysis; their risk of bias was assessed separately using the Newcastle-Ottawa Scale, and their findings are interpreted with explicit recognition of confounding risk.

Study selection

After duplicate removal, two reviewers independently screened titles and abstracts; any record that could not be confidently excluded was retrieved in full text. Full-text decisions were made by the same two reviewers working independently, with a third reviewer resolving disagreements. The complete selection process is depicted in Figure 1.

Data extraction

One reviewer extracted data onto a standardized form; a second independently verified every entry. Variables captured included study design and follow-up; patient demographics and ASA status; anesthetic technique and intrathecal opioid dose; TAP block approach, local anesthetic, concentration, and volume; comparator identity; background analgesic protocol; and all reported outcomes. When standard deviations were missing, they were derived from standard errors, confidence intervals, or interquartile ranges using established conversion formulas.

Risk of bias assessment

RCT quality was assessed with the Cochrane RoB 2 tool across its five standard domains, each rated low risk, some concerns, or high risk. Observational studies were evaluated with the Newcastle-Ottawa Scale (NOS; 7–9 = low risk, 4–6 = moderate, ≤3 = high). Both tools were applied independently by two reviewers, with consensus resolving discrepancies.

Outcomes

The primary outcome was total opioid consumption within the first 24 h following cesarean delivery, expressed in morphine milligram equivalents (MME) where necessary to harmonize across different opioid agents. Secondary outcomes included: (1) pain scores at rest and on movement at 2, 6, 12, and 24 h postoperatively; (2) time to first analgesic request; (3) incidence of postoperative nausea and vomiting (PONV); (4) incidence of adverse effects (pruritus, sedation, respiratory depression); (5) patient satisfaction with postoperative analgesia; and (6) quality of recovery (assessed with validated scales where available, including the QoR-15).

Statistical analysis

Meta-analysis was performed when studies were sufficiently homogeneous in outcome definition, timing, and measurement. The standardized mean difference (SMD, Hedges' g) was selected as the pooled effect measure for two reasons: first, opioid consumption was reported in different units and using different agents (intravenous morphine, fentanyl, tramadol, oxycodone), making a uniform absolute scale unavailable without conversion assumptions; second, SMD standardizes within each individual study and is therefore independent of cross-study unit assumptions. Where studies reported sufficient raw data, absolute opioid consumption was additionally summarized in morphine milligram equivalents (MME) for narrative comparison, using pre-specified conversion factors: IV morphine 1 mg = 1 MME; IV fentanyl 1 mcg = 0.1 MME; tramadol 10 mg = 1 MME; IV meperidine 10 mg = 1 MME; oral oxycodone 1 mg = 1.5 MME. Random-effects pooling used the DerSimonian–Laird estimator.

Statistical heterogeneity was quantified using the I² statistic and Cochran's Q test. I² values of <25%, 25%–50%, 50%–75%, and >75% were considered to reflect low, moderate, substantial, and considerable heterogeneity, respectively. Pre-specified subgroup analyses were conducted based on: (1) type of anesthesia (general vs. spinal/neuraxial); (2) use of intrathecal morphine (yes vs. no); (3) comparator type (placebo/no block vs. active comparator); and (4) TAP block approach (posterior vs. lateral vs. landmark technique). Sensitivity analyses were performed by excluding studies with active comparators, studies using intrathecal morphine, and studies judged to be at high risk of bias. Publication bias was evaluated using funnel plots and Egger's regression test when ≥10 studies contributed to a pooled estimate. All analyses were conducted in R (version 4.3.1) using the meta and metafor packages. Statistical significance was defined as a two-sided p < 0.05.

Qualitative synthesis

Studies that could not be pooled due to heterogeneous outcome definitions, varied comparators, or non-standardized analgesic units were analyzed narratively per the SWiM framework. We grouped them by anesthetic technique, ITM use, and comparator type, then characterized direction of effect, statistical significance, and clinical relevance within each cluster.

Results

Study selection

Database searching retrieved 123 records; 17 duplicates were removed, leaving 106 for abstract review. Forty-eight were excluded at that stage for irrelevant intervention, population, or design. Of the 58 full-text reports reviewed, 40 did not qualify: inappropriate comparator (n = 12), non-cesarean population (n = 9), no relevant pain outcome (n = 7), duplicate cohort (n = 6), or insufficient extractable data (n = 6). Eighteen studies were included in the systematic review; four provided the numerical data needed for quantitative meta-analysis. The selection flow is shown in Figure 1.

Study characteristics

The 18 studies span 2008 to 2024 and enrolled approximately 1,824 patients combined, with individual samples ranging from 30 (28) to 402 (13). Fourteen were RCTs; two were retrospective cohort studies (12, 13), and two were prospective three-arm comparative trials (14, 15). The geographic distribution was broad: Ireland (16), Saudi Arabia (17), Singapore (18), Iran (19), the United States (13, 20), Canada (21, 22), India (15, 23–26), Egypt (27), Turkey (28), Poland (14), and China (12, 29). Full study characteristics are summarized in Table 1.

Table 1. Characteristics of included studies (n = 18).

CSE, combined spinal-epidural; GA, general anesthesia; ITM, intrathecal morphine; LoR, loss of resistance technique; LB, liposomal bupivacaine; MME, morphine milligram equivalents; NRS, numerical rating scale; PCA, patient-controlled analgesia; POD, postoperative day; PSM, propensity score matching; QLB, quadratus lumborum block; QoR-15, Quality of Recovery-15 scale; RCT, randomized controlled trial; Retro, retrospective; TFP, transversalis fascia plane block; US, ultrasound; VAS, visual analog scale.

Four studies used general anesthesia; the remaining 14 used spinal anesthesia, three of which added intrathecal morphine. Ultrasound guidance was used in 16 of 18 studies; the two earliest (16, 19) relied on the landmark loss-of-resistance technique. Local anesthetic agents included ropivacaine (0.25%–0.5%), bupivacaine (0.25%), levobupivacaine (0.25%–0.375%), and liposomal bupivacaine, with volumes of 15–20 mL per side in most cases. Four studies used an active regional comparator: wound infiltration (27), quadratus lumborum block (14), or transversalis fascia plane block (15).

Risk of bias

Of the 16 RCTs and prospective trials, ten received low-risk ratings across all five RoB 2 domains (D1: randomization; D2: deviations from intended interventions; D3: missing outcome data; D4: outcome measurement; D5: selective reporting). Four studies received some concerns: Tan et al. (D2: incomplete blinding of block operator, inherent to wound infiltration comparison), Fusco et al. (D2: same), Lee et al. (D5: selective reporting of secondary time-points), and Srivastava et al. (D2: deviations in background analgesic protocol). Two studies were rated high risk in at least one domain: Mankikar et al. (D3: incomplete outcome data; D5: selective endpoint reporting) and Buluc et al. (D2: unblinded intervention allocation; D4: unblinded outcome assessment). Excluding these two high-risk studies from the qualitative synthesis did not change the direction of findings in either subgroup in which they appeared. The two retrospective cohort studies (Tao et al.: NOS 7/9; Peebles et al.: NOS 6/9) carry moderate risk from unmeasured confounding. Figure 2 presents the full risk of bias summary.

Primary outcome: 24 h opioid consumption. Quantitative Synthesis

Four studies with adequate, homogeneous data (N = 193) were pooled. DerSimonian–Laird random-effects analysis showed a statistically significant reduction in 24 h opioid consumption favoring TAP block (SMD = −2.30, 95% CI −4.24 to −0.36; p = 0.02). Heterogeneity was extreme (I² = 97.0%; Q-test p < 0.001), however, meaning this pooled figure is better understood as a rough average across very different clinical contexts than as a precise summary estimate. The variation itself is the more informative result. The forest plot is in Figure 3.

The remaining 14 studies were analyzed narratively; heterogeneous outcomes, varied comparators, and non-standardized analgesic units made quantitative pooling inappropriate.

Subgroup analyses

Table 2 summarizes the pre-specified subgroup analyses by anesthetic technique and ITM use.

Table 2. Summary of meta-analysis and subgroup analyses.

CI, confidence interval; ITM, intrathecal morphine; SMD, standardized mean difference (Hedges’ g). Negative SMD values indicate benefit for the TAP block group. Heterogeneity assessed using the I² statistic.

In the GA subgroup, all four studies—one contributing to the quantitative pool and three analyzed narratively—consistently reported clinically meaningful opioid-sparing. This qualitative consistency across independent studies from different settings and eras constitutes the primary evidence for TAP block benefit under general anesthesia. For completeness, a pooled SMD was calculable from the single quantitative study (SMD = −6.54, 95% CI −8.11 to −4.98); this figure should not be interpreted as a stable summary estimate, as a single-study subgroup has no within-subgroup heterogeneity to quantify and the effect size may reflect study-specific characteristics. The GA finding is best treated as qualitative and hypothesis-generating, requiring prospective replication in adequately powered trials.

Where ITM was used alongside spinal anesthesia, TAP block produced a near-zero pooled estimate (SMD = 0.12, 95% CI −0.34 to 0.58; p = 0.61). The narrative studies corroborated this: McKeen et al. found no improvement at any time point in 74 patients; Lee et al. documented a 2 h advantage that had disappeared entirely by 24 h; and Singh et al., comparing two ropivacaine doses against an ITM background, found no primary endpoint difference, with only the high-dose arm showing modest transient reductions at 6 and 12 h.

Qualitative synthesis by clinical context

TAP block under general anesthesia (4 studies)

All four GA studies reported significant opioid-sparing. McDonnell et al. found cumulative morphine use of 6 mg vs. 33 mg over the first 12 h (p ≤ 0.001) and median time to first opioid request increased from 90 to 220 min. Eslamian et al. reported markedly lower VAS scores at rest and on coughing, tramadol requirements reduced from 250 to 75 mg (p < 0.001), and time to first rescue analgesic delayed by more than three hours (210 vs. 30 min). Buluc et al. observed that no TAP patient required supplemental analgesia beyond the PCA protocol, compared with 11 of 15 controls. Tao et al., in a propensity-matched cohort, documented a 10-point improvement in QoR-15 at 24 h, shorter time to ambulation, and earlier return of intestinal function.

TAP block under spinal anesthesia without intrathecal morphine (8 studies)

Six of the eight spinal/no-ITM studies showed statistically significant benefit. McDonnell et al., Baaj et al., Srivastava et al., Mankikar et al., Fusco et al., and Jadon et al. all reported meaningful reductions in opioid or analgesic requirements, though absolute magnitudes differed. Jadon et al.'s results were among the most striking: the median time to first analgesic request extended from 4 to 11 h (p < 0.0001), and median tramadol use dropped from 2 doses to zero. Srivastava et al. recorded a 50% reduction in tramadol over 48 h. Fusco et al. added an important technical observation, when the block was performed correctly under direct ultrasound visualization, far fewer patients crossed the VAS ≥4 threshold, underscoring that technique quality matters. In Borys et al.'s three-arm comparison both TAP block and QL block outperformed sham injection, with QL producing somewhat better pain control at select time points; and Mankikar et al. more than doubled the rescue-free window from 4.1 to 9.5 h.

Two studies in this subgroup found no significant benefit. Yu et al. tested the block against a background of scheduled tramadol, celecoxib, and paracetamol with oxycodone on demand, a rigorous oral multimodal regimen, and found it added nothing. When that analgesic space is already occupied, the block's contribution appears negligible. Sripriya et al. told a slightly different story: neither posterior TAP nor transversalis fascia plane block reduced the total number of rescue analgesic doses, yet TAP block did meaningfully extend the pain-free interval (6.89 vs. 4.76 h; p < 0.001).

TAP block in the presence of intrathecal morphine (3 studies)

Three studies specifically examined TAP block as an add-on to ITM-based spinal anesthesia. Lee et al. saw a real early advantage, rest pain 0.5 vs. 2.8 and movement pain 1.9 vs. 4.9 at 2 h (p < 0.001), but it was entirely gone by 24 h, with no difference in pain scores or opioid use at 24 or 48 h. McKeen et al. found no benefit at any time point in patients receiving ITM doses of 0.1–0.2 mg. Singh et al., who explored the dose question with high (3 mg/kg) and low (1.5 mg/kg) ropivacaine against an ITM 150 mcg background, found no primary endpoint difference at 24 h; the high-dose arm showed only modest secondary reductions at 6 and 12 h. Across all three trials the pattern is consistent: once ITM is part of the regimen, the TAP block's incremental contribution is negligible, and its routine addition is not justified.

TAP block versus active regional comparators (3 studies)

El-Morsi et al. randomized patients to either TAP block or wound infiltration, both delivering bupivacaine 0.25% in equivalent volumes. Fentanyl PCA use at 24 h and all secondary outcomes were statistically indistinguishable, suggesting that delivery route matters less than total local anesthetic deposited in the abdominal wall. Borys et al.'s direct TAP-versus-QL comparison found that QL produced modestly better pain control at 2 and 8 h, with similar total morphine consumption overall. Sripriya et al. found no difference between posterior TAP and transversalis fascia plane block, and neither technique reduced rescue analgesic requirements relative to an untreated control.

Liposomal bupivacaine formulation (1 study)

Peebles et al. examined liposomal bupivacaine TAP block (n = 107) and liposomal bupivacaine wound infiltration (n = 185) against spinal-only standard care (n = 110) in a retrospective cohort of 402 patients. Both active arms produced significantly lower daily opioid requirements and pain scores on days 0 and 1 (p < 0.001). The two active arms were indistinguishable from each other, consistent with what was observed using conventional bupivacaine formulations, the extended-duration agent did not change which technique came out ahead.

Secondary outcomes

Pain scores at rest and on movement were among the most widely reported secondary outcomes. In the GA and spinal/no-ITM groups, TAP block consistently lowered scores at 2, 6, and 12 h; the benefit typically attenuated or disappeared by 24 h, in keeping with the 8–16 h functional duration of bupivacaine and ropivacaine. Time to first analgesic request was extended in every study that measured it within the spinal/no-ITM context, with the pain-free window lengthened by approximately 4 h in some series (25) to more than 7 h in others (26).

PONV rates were lower in several GA-subgroup studies (16, 18), a predictable downstream effect of reduced systemic opioid exposure. Patient satisfaction tracked opioid sparing: studies demonstrating clear analgesic benefit consistently reported higher satisfaction scores in the TAP group (17, 23, 26). One serious adverse event occurred across the entire dataset: Jadon et al. described a patient who developed systemic local anesthetic toxicity with convulsions, which resolved with intravenous midazolam and left no long-term sequelae.

Quality of recovery assessed by QoR-15 was a primary endpoint only in Tao et al. TAP block produced a median improvement of 10 points (95% CI 8–12; p < 0.001), exceeding the instrument's minimum clinically important difference, driven by gains across the pain, physical comfort, and emotional well-being domains.

Discussion

Across 18 studies and approximately 1,824 patients, TAP block is associated with a statistically significant reduction in 24 h post-cesarean opioid consumption. The pooled estimate sits alongside extreme heterogeneity (I² = 97%), which is not a limitation to explain away, it is a signal. Two clinical variables consistently drive that variation: the anesthetic technique used and whether intrathecal morphine was part of the regimen.

The GA subgroup provides the most consistent evidence for TAP block benefit. With no neuraxial analgesia in place, the block addresses anterior abdominal wall somatic pain without competition, and all four GA studies reported clinically meaningful opioid-sparing. General anesthesia accounts for roughly 5%–15% of cesarean deliveries at many institutions and considerably more where preservative-free morphine is unavailable or urgent fetal compromise precludes neuraxial placement (30). For those patients, available evidence supports strong consideration of TAP block as a component of postoperative analgesia. This suggestion is tempered by important limitations: the quantitative evidence rests on a single study in the meta-analytic pool, with narrative support from three others—consistent in direction but limited in aggregate depth—and prospective, adequately powered trials are required before formal guideline endorsement. When intrathecal morphine is part of the spinal technique, the block adds negligible incremental benefit and resources are better directed toward ITM dose optimization and side-effect management.

The picture reverses when ITM is part of the spinal technique. Across the three dedicated ITM studies, the result is either no benefit or an advantage confined to the first 2 h that disappears before the next morning. The pharmacology explains it: ITM generates durable spinal opioid receptor-mediated analgesia covering both somatic and visceral components for up to 24 h (31), leaving a peripheral fascial plane block very little additional pain to address. Abdallah et al.'s earlier meta-analysis reached the same conclusion (32), and the present data reinforce it.

Spinal anesthesia without ITM, whether because morphine is unavailable, opioids are contraindicated, or the institution follows a minimization protocol, is the other clinical scenario where TAP block reliably contributes. Most studies in this subgroup reported significant reductions in rescue opioid use and a longer pain-free interval. The two exceptions are instructive rather than contradictory. Yu et al. ran their trial against a background of scheduled tramadol, celecoxib, and paracetamol with on-demand oxycodone; in that setting the block had no analgesic space left to occupy. That is less a failure of the technique than a demonstration of what structured oral multimodal analgesia can achieve (33). Where such regimens cannot be implemented or reliably adhered to, TAP block fills the gap effectively.

Active comparator data yield two consistent conclusions. TAP block and wound infiltration perform essentially the same when local anesthetic volume and concentration are matched (13, 27), a finding with practical implications when time is short. The QL block appears modestly superior at certain time points (14), plausibly because its posterior spread can reach the paravertebral space and capture visceral afferents that TAP cannot. That advantage is real but small, and the QL block is technically more demanding. Notably, no trial has yet compared the two techniques in an ITM-inclusive setting, so their relative utility in contemporary practice remains incompletely defined (34, 35).

An I² of 97% could be read as a reason to distrust the overall pooled estimate (36). We would read it differently: it tells us that a single summary number would conceal more than it reveals, and that the variation itself is structured, mapping directly onto the GA-versus-spinal distinction and the presence or absence of ITM. Stratifying by those variables, rather than averaging over them, is what makes the literature coherent and actionable.

Limitations

Several limitations deserve mention. Only four studies contributed to the quantitative pool, limiting the precision of our effect estimates; the qualitative synthesis adds breadth but cannot substitute for that precision. Technique variability across trials, block approach (lateral, posterior, landmark), local anesthetic choice, concentration, and timing, contributed heterogeneity that subgroup analyses could not fully resolve. Background analgesic regimens ranged from tramadol-on-demand to structured multimodal schedules, and that variability almost certainly interacted with TAP block efficacy in ways not captured here. The two observational studies carry the usual risk of unmeasured confounding. Formal publication bias assessment was not possible given the small quantitative pool. Finally, nearly every study reported only short-term outcomes; Singh et al.'s 6- and 12-week data are the lone exception, and they showed no difference at either time point, which is useful, but an insufficient basis for conclusions about chronic pain.

Clinical implications

Available evidence supports context-guided rather than universal TAP block use, with all observations below framed as hypothesis-generating and subject to the important quantitative limitations described above. Under general anesthesia, TAP block should be strongly considered as a component of postoperative analgesia; four independent studies show consistent directional benefit, though formal guideline endorsement awaits adequately powered prospective trials. When intrathecal morphine is part of the spinal technique, the available evidence does not support routine TAP block use. In patients receiving spinal anesthesia without ITM, TAP block appears to provide clinically meaningful analgesia and may reasonably be incorporated into multimodal regimens, with the caveat that benefit is attenuated when structured oral analgesia is already reliably implemented. In all contexts, incremental analgesic benefit must be weighed against procedural demands: trained personnel, ultrasound equipment, dedicated time, and a real if uncommon risk of local anesthetic toxicity documented in one case in this review. Where benefit is modest or uncertain, this cost-benefit balance may not favor routine use. The QL block may offer modestly superior coverage at select time points, but its greater technical complexity must be weighed accordingly.

Future research

Future trials should adopt standardized outcome reporting, ideally anchored to the IMMPACT core set, and mandate ITM use as a pre-specified stratification variable rather than treating it as a covariate after the fact (37). Direct TAP-versus-QL comparisons in ITM-free settings would clarify the best regional technique for that population. Prospective randomized trials of liposomal bupivacaine with adequate sample sizes and active controls are overdue given how widely this formulation is now used. And the value of continuous catheter-based TAP infusion over single-shot block in the GA setting, where the block's contribution is clearest and duration of analgesia is most critical, has not been rigorously studied.

Conclusions

TAP block reduces post-cesarean opioid consumption, but it does not do so equally across all clinical settings. Benefit is robust under general anesthesia, meaningful when spinal anesthesia is used without intrathecal morphine, and essentially absent when ITM is already in place. The clinical message is neither to abandon the block broadly nor to apply it universally, but to use it where the evidence is strongest; a distinction this review now defines with reasonable clarity. Prospective trials with standardized outcomes and pre-stratified ITM status are needed to sharpen these recommendations further.

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Footnotes

Edited by: Tao Xu, International Peace Maternity and Child Health Hospital, China

Reviewed by: Filippo Alberto Ferrari, Sacro Cuore Don Calabria Hospital (IRCCS), Italy

Kazutoshi Onitsuka, Kagoshima University Hospital, Japan

Leyla Baghirzada, University of Calgary, Canada