Optimizing transversus abdominis plane blocks in colorectal surgery: methodological queries and the fundamental question of indication

Abstract

This letter to the editor critically appraises the recent trial by Li et al. evaluating liposomal bupivacaine transversus abdominis plane (TAP) blocks in laparoscopic colorectal surgery. First, we raise three methodological concerns: the complete absence of a justified sample size calculation, an implausibly large 36-point difference in Quality of Recovery-40 (QoR-40) scores that far exceeds the accepted minimal clinically important difference, and the concerning inclusion of irrelevant references to support liposomal bupivacaine. Beyond these specific queries, we address a conceptually important clinical framework. Relying on the landmark CLEVELAND trial as a counterweight, we emphasize that within a true multimodal analgesia (MMA) pathway, routine TAP blocks may offer limited incremental benefits because they primarily target somatic rather than predominant visceral pain. We strongly advocate that TAP blocks must transition from a habitual, universal protocol to highly selective, indication-based utilization; not every patient requires a TAP block.

Dear Editor,

We read with great interest the recent randomized controlled trial by Li et al. [1] evaluating the efficacy of liposomal bupivacaine transversus abdominis plane (TAP) blocks in enhancing recovery following laparoscopic colorectal cancer resection. While we appreciate the effort to explore long-acting regional anesthetic formulations, we must raise three critical methodological concerns, alongside a fundamental clinical repositioning regarding the routine indication for this block.

First, the manuscript lacks a formal sample size calculation. The enrollment of exactly 60 patients (30 per group) is presented without explicit justification. To verify that the study was adequately powered rather than a mere convenience sample, the authors should clarify the expected effect size, statistical power, and alpha error probability upon which this cohort size was based.

Second, the reported 36-point difference in the Quality of Recovery-40 (QoR-40) scores at 72 h (188 vs. 152) is highly unusual. The established minimal clinically important difference (MCID) for the QoR-40 is typically 6 to 10 points [2]. An effect size of this magnitude appears clinically extraordinary and warrants careful verification. We urge the authors to confirm the veracity of these data and clarify whether baseline differences or other unmeasured confounders heavily contributed to this disparity.

Third, a review of the bibliography reveals a concerning lack of academic rigor. References 7 through 13 are cited to support the application of liposomal anesthetics; however, several discuss completely unrelated topics, such as magnetic nanogels for rat shoulder blocks (Ref. 7), magnesium sulfate for varicocelectomy (Ref. 8), and pediatric magnetic resonance imaging (MRI) anesthesia (Ref. 13). We request a verification of these references, as such inaccuracies compromise the manuscript’s credibility.

While these methodological clarifications are strictly necessary, we believe this study inherently prompts a much more fundamental clinical question. Currently, prevailing guidelines advocate for the TAP block as an integral component of multimodal analgesia (MMA) [3]. Consequently, administering a TAP block has become a universal, “one-size-fits-all” reflex. However, minimally invasive colorectal surgery is heterogeneous, and perioperative strategies should be adapted to the patient and procedural context rather than applied as a uniform package [4].

The recent landmark CLEVELAND trial [5] provides a crucial counterweight to this universal consensus. Strikingly, this rigorous 261-patient trial specifically investigated the exact intervention utilized by Li et al. (liposomal bupivacaine TAP). Unambiguously, when embedded within a strictly applied modern MMA framework, liposomal bupivacaine TAP blocks yielded no detectable differences in opioid consumption or pain scores compared to saline placebos. While this single trial may not serve as the final verdict, this robust evidence seriously undermines the routine, universal application of these blocks.

The physiological basis underpinning this debate is nuanced. We fully acknowledge that TAP blocks provide reliable somatic blockade of the anterior abdominal wall and can reduce initial opioid consumption. However, their value may vary significantly depending on extraction site size, hybrid access, and individual pain phenotypes. They do not sufficiently address the visceral pain (peritoneal irritation and mesenteric traction) that heavily dominates the experience of laparoscopic colorectal surgery. Systemic analgesics and kappa-opioid agonists remain clinically indispensable precisely because visceral pain is mediated via visceral pathways [6].

Furthermore, for purely laparoscopic procedures where extraction incisions are minimal, the incremental benefit of a TAP block over simple local wound infiltration (LWI) is often clinically negligible. Recent robust randomized trials have demonstrated that, within an optimized MMA setting, TAP blocks do not provide superior postoperative analgesia compared to simple LWI for small incisions in laparoscopic colorectal cancer resections [7, 8]. Given the health economics, time, and procedural resources required for ultrasound-guided blocks, LWI represents a highly cost-effective and practical choice for minimal incisions.

Therefore, we must strongly emphasize that the application of TAP blocks must transition from an unquestioned routine to selective, indication-based use. Modern colorectal care is moving toward stratified, decision-supported, individualized pathways rather than universal routine components [9]. Rather than an automatic default, their application should be matched to the actual somatic pain burden and reserved exclusively for scenarios offering genuine incremental value: (1) larger extraction-incision laparoscopic cases, where the abdominal wall somatic burden is disproportionate relative to the intracorporeal component; (2) hand-assisted or hybrid procedures, recognizing that minimally invasive colorectal operations differ substantially in abdominal wall trauma and technical conduct [10]; (3) patients with significant opioid intolerance for whom exhausting all non-opioid somatic options is mandatory; or (4) cases where continuous catheter techniques provide sustained, titratable coverage.

In conclusion, before endorsing liposomal bupivacaine for routine use, the methodology and bibliography of the underlying evidence must be rigorously verified. More importantly, through careful clinical stewardship, analgesic adjuncts should be used according to their incremental value within a modern MMA and enhanced recovery pathway (ERP), not by habit. Shifting the debate from “does this formulation work?” to “who actually needs the block?” ensures a more responsible and patient-centered approach to postoperative pain management.

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

During the preparation of this manuscript, the authors used large language models primarily to improve readability, perform English language polishing, and assist with structural refinement. After using these tools, the authors rigorously reviewed and edited the content as needed. The core clinical insights, literature interpretation, methodological critiques (including the identification of irrelevant references), and final conclusions were conceived and developed exclusively by the human authors. The authors take full and sole responsibility for the final content, scientific accuracy, and underlying viewpoints expressed in this publication.

Author contributions

Han Chao proposed the main concept, Jing Yibing wrote the draft, and Han Chao revised it. All authors reviewed the manuscript.

Data availability

No datasets were generated or analysed during the current study.

Declarations

Competing interests

The authors declare no competing interests.