Paradigm shift in postoperative monitoring: Integrating dynamic ultrasound and biomarkers for precision management following laparoscopic gastrectomy

Abstract

The advent of laparoscopic gastrectomy has significantly advanced the surgical management of gastric cancer by emphasizing minimally invasive techniques and enhanced recovery protocols. Nevertheless, postoperative intraperitoneal effusion remains a frequent and potentially severe complication, with risks including infection, abscess formation, and anastomotic leakage. Conventional monitoring methods, which rely on clinical symptoms and nonspecific inflammatory markers, often result in delayed diagnosis, thereby missing the critical window for early intervention. The recent study by Gao et al, published in World Journal of Gastrointestinal Surgery, presents a robust framework for a more refined and integrated surveillance approach. The authors demonstrate that systematic transabdominal ultrasonography-particularly when differentiating the nature of effusion (simple vs mixed)-combined with serial measurements of the biomarker procalcitonin, enables accurate identification of high-risk patients at the crucial 72-hour postoperative milestone. This editorial critically evaluates these findings, situates them within the broader context of enhanced recovery after surgery principles and precision medicine, and explores their implications for advancing clinical practice. We contend that the integration of dynamic, multimodal monitoring represents an essential shift from reactive complication management to proactive risk stratification and prevention, with the ultimate goal of improving patient outcomes and optimizing healthcare efficiency in surgical oncology.

Key Words: Laparoscopic gastrectomy; Postoperative complications; Intraperitoneal effusion; Ultrasound monitoring; Procalcitonin; Biomarkers; Predictive model; Precision surgery

Core Tip: Postoperative intraperitoneal effusion remains a significant clinical challenge following laparoscopic gastrectomy. This editorial highlights a paradigm shift toward proactive and precision-driven postoperative monitoring, as supported by emerging evidence. The integration of dynamic transabdominal ultrasonography-particularly the assessment of effusion characteristics (simple vs mixed echogenicity) at the critical 72-hour postoperative milestone-with serial procalcitonin measurements constitutes a superior dual-modality strategy for early risk stratification. This combined approach enables the timely identification of high-risk patients who are likely to develop infectious complications before clinical deterioration occurs. Incorporating this structured surveillance protocol into enhanced recovery after surgery pathways exemplifies a transition from reactive management to preemptive intervention, thereby improving patient outcomes, optimizing resource utilization, and advancing the delivery of personalized postoperative care in surgical oncology.

This editorial refers to “Dynamic ultrasound monitoring of intraperitoneal effusion for predicting complications after laparoscopic gastrectomy” by Gao et al, 2026; https://doi.org/10.4240/wjgs.v18.i1.113894.

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INTRODUCTION

Laparoscopic gastrectomy has become the standard surgical approach for resectable gastric cancer, with well-established advantages over open surgery, including reduced blood loss, less postoperative pain, shorter duration of postoperative ileus, and improved cosmetic outcomes[1-3]. These benefits align closely with the principles of enhanced recovery after surgery (ERAS) protocols, which aim to minimize the surgical stress response and expedite functional recovery[4,5]. Despite these advancements, postoperative morbidity remains a significant clinical concern, with reported rates ranging from 15% to 30%[6]. Among such complications, intraperitoneal fluid collections are common, affecting a substantial proportion of patients[7].

While most postoperative effusions are benign-representing reactive serous fluid or lymphatic leakage that is gradually reabsorbed-a clinically critical subset may progress to infected collections or abscesses. These often arise from subclinical anastomotic leaks, ischemic tissue, or bacterial translocation[8,9]. The central clinical challenge lies in the early and accurate identification of this high-risk group. Conventional monitoring strategies, which rely on fever, leukocytosis, elevated C-reactive protein (CRP), or physical examination findings, are inherently limited. Clinical symptoms are nonspecific and typically emerge only after an infectious process has already developed. CRP, although sensitive to inflammation, lacks specificity as it is elevated in response to surgical trauma alone[10], with peak levels commonly observed on postoperative days (POD) 2-3, thereby limiting its utility for early detection of infection[11].

This diagnostic delay creates a critical gap between the onset of pathological changes and the initiation of therapeutic intervention, increasing the risk that a simple fluid collection may evolve into a complex, walled-off abscess or lead to systemic sepsis[12]. Therefore, there is a pressing need for more effective monitoring tools capable of providing earlier and more specific indicators of complications. Imaging modalities, particularly bedside transabdominal ultrasound, offer a non-invasive, repeatable, and radiation-free method for evaluating the peritoneal cavity[13-15]. However, its application has traditionally been reactive and opportunistic, initiated based on clinical suspicion rather than integrated into a structured surveillance protocol[16]. The study by Gao et al[17] aims to systematize this approach by advancing beyond mere detection of fluid accumulation to assessing its dynamic characteristics and integrating these findings with serial measurements of advanced inflammatory biomarkers.

DECONSTRUCTING THE STUDY: KEY CONTRIBUTIONS AND MECHANISTIC INSIGHTS

In a recent issue of the World Journal of Gastroenterology Surgery, Gao et al’s retrospective analysis of 80 patients establishes several evidence-based foundations for a refined postoperative monitoring strategy[17]. The first major contribution lies in the clear characterization of the natural history of postoperative intraperitoneal effusion. By standardizing ultrasound assessments on POD 1, 3, and 7, the authors demonstrate that both the incidence and volume of effusion peak on POD 3. This temporal pattern is consistent with the established pathophysiology of the postoperative inflammatory response, during which cytokine release and vascular permeability reach their maximum around 72 hours[10]. This observation provides strong justification for designating POD 3 as a pivotal time point for clinical evaluation within structured surveillance protocols.

The second and potentially most impactful contribution is the prognostic validation of effusion characteristics through ultrasonographic classification[18]. The authors employ a binary categorization “simple” (anechoic) vs “mixed” (containing internal echoes, septations, or echogenic foci)-which serves as a clinically practical and highly discriminatory tool. The study findings are compelling: Patients with mixed effusions exhibited a 3.86-fold higher risk of complications, with a complication rate of 50% compared to 9.3% in those with simple effusions. This imaging finding transcends radiological observation; it functions as a visual biomarker of localized pathological processes. Internal echoes likely reflect cellular debris, fibrin deposition, and protein-rich exudate-hallmark features of an exudative or infectious process, as opposed to a transudative origin. This linkage enhances the interpretive value of imaging by bridging morphological findings with underlying immunological and microbiological mechanisms.

The third key component is the strategic integration of systemic biomarkers, specifically procalcitonin (PCT)[19,20]. The study confirms that PCT outperforms both CRP and white blood cell count in predicting infectious complications, demonstrating an area under the curve of 0.874 at an optimal cutoff of 0.47 ng/mL on POD 3. As a precursor of calcitonin, PCT is selectively upregulated in response to bacterial infection and systemic inflammation mediated by pro-inflammatory cytokines such as interleukin-1β and tumor necrosis factor-α[21,22]. Notably, its elevation is minimal in the context of sterile surgical trauma[23,24]. Consequently, elevated PCT levels in conjunction with a mixed effusion provide a critical “second signal”, reinforcing the suspicion of bacterial colonization or infection and thereby enhancing the diagnostic accuracy of imaging alone. These results are consistent with prior studies affirming the utility of PCT in identifying postoperative intra-abdominal infections[25-27].

Finally, the authors identify clinically relevant pre- and perioperative risk modifiers. The association between total gastrectomy (vs distal gastrectomy) and a 2.10-fold increased risk of effusion highlights the influence of surgical extent and the degree of lymphatic disruption. Similarly, the correlation with diabetes mellitus underscores the adverse effects of impaired microcirculation and immune dysfunction on postoperative recovery. These factors enable risk stratification prior to and during surgery, allowing clinicians to identify patients who require intensified postoperative monitoring.

It is important to acknowledge that the study by Gao et al[17] is retrospective and involves a selective patient cohort, including those with early drain removal (≤ 48 hours). This inclusion criterion, while methodologically justified for assessing the “natural” evolution of postoperative effusion, introduces a substantial selection bias toward lower-risk patients. In many clinical centers, particularly following total gastrectomy, drains are typically retained beyond 48 hours. Consequently, whether the predictive model derived from this cohort can be generalized to routine clinical practice remains uncertain. Moreover, the limited sample size-especially the small number of total gastrectomy cases (n = 24)-constrains the statistical power of subgroup analyses. Therefore, while the study provides compelling hypothesis-generating evidence, its findings must be validated in prospective, multicenter cohorts that reflect real-world clinical practice. These methodological limitations necessitate cautious interpretation and emphasize the need for rigorous validation before broad implementation.

CONTEXTUALIZING WITHIN THE ERAS AND PRECISION MEDICINE FRAMEWORK

The findings of this study align closely with the dual paradigms of ERAS and precision medicine[28]. ERAS protocols extend beyond accelerating hospital discharge; their primary objective is to optimize physiological homeostasis and minimize surgical stress to prevent postoperative complications[4,29]. A fundamental principle underpinning these protocols is “prevention rather than treatment”. While current ERAS guidelines for gastrectomy emphasize multimodal analgesia, early nutritional support, and prompt mobilization, they provide limited specific recommendations regarding active surveillance for intra-abdominal complications[4]. The monitoring protocol proposed by Gao et al[17] routine transabdominal ultrasound on POD 1, 3, and 7 for high-risk patients-can be readily integrated into existing ERAS pathways. This represents a shift from passive observation (watchful waiting) to proactive, structured surveillance, which may yield economic benefits by preventing resource-intensive complications[30].

This approach is fully consistent with the principles of precision medicine, which seeks to individualize clinical decisions and therapeutic interventions based on patient-specific characteristics. In this context, a uniform, “one-size-fits-all” model of postoperative monitoring is no longer tenable. The study offers a framework for risk-stratified care: Low-risk patient (undergoing distal gastrectomy, without diabetes, exhibiting simple effusion on POD 3, and demonstrating low PCT levels): Likely requires only standard postoperative monitoring.

High-risk patient (undergoing total gastrectomy, with comorbid diabetes, presenting mixed effusion on POD 3, and elevated PCT): Warrants heightened surveillance, consideration for empirical antibiotic therapy, or pre-emptive image-guided drainage. This risk-adapted strategy enhances clinical efficiency by directing resources and interventions to patients at greatest risk, thereby improving outcomes while minimizing unnecessary procedures in low-risk individuals.

Table 1 summarizes the key distinctions between traditional symptom-driven monitoring and the integrated ultrasound-biomarker surveillance approach. The integrated surveillance strategy, informed by the findings of Gao et al[17], shifts postoperative management from a reactive, symptom-driven model to a proactive, structured approach. By combining standardized transabdominal ultrasonography (assessing effusion type) with serial PCT measurement, this strategy enables early risk stratification at postoperative day 3, facilitates pre-emptive intervention, and aligns with the preventive principles of ERAS.

Table 1 Comparison of traditional monitoring vs integrated ultrasound-biomarker surveillance.

Characteristic	Traditional monitoring	Integrated surveillance
Monitoring philosophy	Reactive-triggered by clinical suspicion	Proactive-structured, scheduled assessments
Timing of assessment	As needed, based on symptoms or laboratory changes	Standardized: POD 1, 3, and 7
Primary indicators	Clinical signs (fever, abdominal pain, distension), CRP, WBC count	Ultrasound effusion type (simple vs mixed) + procalcitonin (PCT)
Intervention trigger	Clinical deterioration or laboratory confirmation of infection	Combined imaging + biomarker threshold (POD 3: Mixed effusion + PCT > 0.47 ng/mL)
Timing of intervention	Often delayed (POD 5-7)	Earlier, pre-emptive (POD 3-5)
Risk stratification capability	Limited-unable to differentiate high-risk from low-risk patients early	Yes-enables early identification of high-risk patients based on effusion characteristics and PCT levels
Alignment with ERAS principles	Partial-primarily diagnostic rather than preventive	Full-aligns with “prevention rather than treatment” core principle
Evidence base	Well-established, but with recognized limitations for early detection	Emerging-requires prospective, multicenter validation
Resource requirements	Low-relies on clinical examination and routine laboratory tests	Moderate-requires trained sonographers, ultrasound equipment, and serial PCT assays

POD: Postoperative days; ERAS: Enhanced recovery after surgery; CRP: C-reactive protein; WBC: White blood cell.

LIMITATIONS AND THE ROADMAP FOR FUTURE VALIDATION

As the authors appropriately acknowledge, the study has several inherent limitations, including its retrospective design, single-center setting, and limited sample size. Generalizability is further constrained by the inclusion criterion of early drain removal (≤ 48 hours). While this criterion is methodologically justified for assessing the “natural” accumulation of postoperative fluid, it introduces a selection bias toward a lower-risk patient cohort-namely, those in whom surgeons had sufficient confidence to remove drains early. In many clinical centers, particularly following total gastrectomy, drainage catheters are typically retained beyond 48 hours. Therefore, the predictive accuracy of transabdominal ultrasound and PCT must be validated in a prospective, unselected population that includes patients with prolonged drain placement. It remains unclear whether a mixed effusion adjacent to a drain tract carries the same prognostic significance as one occurring in the absence of a drain.

Moreover, although the proposed clinical algorithm is biologically plausible and logically structured, it requires rigorous prospective validation through an interventional study. The pivotal question is whether implementing this protocol-specifically, initiating early image-guided drainage or antimicrobial therapy in patients with mixed effusion and elevated PCT-leads to improved clinical outcomes compared to standard management. A randomized controlled trial comparing a “dynamic monitoring-guided intervention” strategy with conventional symptom-driven care is the essential next step. Primary and secondary endpoints should include rates of major infectious complications (Clavien-Dindo grade ≥ III), need for reoperation, intensive care unit (ICU) admission, length of hospital stay, and cost-effectiveness.

Future research directions offer significant potential. Could contrast-enhanced ultrasound refine current assessments by enabling better evaluation of perilesional vascularity and tissue necrosis[31]? Can machine learning algorithms be applied to analyze sonographic texture patterns for earlier prediction of effusion complexity[32]? Is there a role for serial cytokine profiling or cellular analysis of effusion fluid obtained via minimally invasive ultrasound-guided aspiration[33]? The study by Gao et al[17] provides a foundational framework that enables these advanced lines of investigation.

LOGISTICAL AND ECONOMIC CONSIDERATIONS

While the integration of serial ultrasound and PCT monitoring demonstrates clear clinical potential, its broad implementation requires careful consideration of practical and operational challenges. From a logistical standpoint, routine postoperative ultrasonography necessitates access to trained sonographers and dedicated equipment, which may pose resource constraints in certain healthcare settings. Similarly, repeated PCT assays entail incremental laboratory costs. However, these expenditures must be evaluated in relation to the substantial financial burden associated with managing severe complications, including image-guided or surgical drainage of abscesses, reoperation, prolonged hospitalization, and ICU admission. Early identification of high-risk patients through this dual-modality approach could enable targeted interventions, potentially preventing such adverse outcomes and demonstrating long-term cost-effectiveness[34]. Formal health-economic evaluations are warranted to assess the cost-benefit profile of incorporating this surveillance strategy into enhanced recovery pathways.

OUR PERSPECTIVE: TOWARD A CLINICAL ALGORITHM

Based on the evidence synthesized from the study by Gao et al[17] and the broader literature, we propose a structured clinical algorithm to operationalize the integrated surveillance strategy (Figure 1). This algorithm represents our independent interpretation of how the evidence might translate into clinical practice, and is intended to complement, rather than replace, clinical judgment.

Figure 1 Integrated surveillance algorithm for postoperative risk stratification following laparoscopic gastrectomy. Based on the findings of Gao et al[17] and our systematic synthesis of the evidence, this algorithm centers on postoperative day 3 as the critical assessment window. Patients are stratified by ultrasound effusion type (simple vs mixed) and procalcitonin level (using the optimal cutoff of 0.47 ng/mL). Low-risk patients continue standard enhanced recovery after surgery pathways, while high-risk patients trigger enhanced surveillance and pre-emptive intervention. This algorithm represents a hypothesis-generating framework requiring prospective validation. PCT: Procalcitonin; ERAS: Enhanced recovery after surgery; CRP: C-reactive protein.

The algorithm centers on the POD 3 assessment, which our analysis confirms as the optimal window for risk stratification. Patients are categorized based on two readily obtainable parameters: Ultrasound effusion type (simple vs mixed) and PCT level (using the optimal cutoff of 0.47 ng/mL derived from the original study). Low-risk patients (simple effusion + PCT ≤ 0.47 ng/mL) can safely continue standard ERAS pathways with routine clinical monitoring. In contrast, high-risk patients (mixed effusion + PCT > 0.47 ng/mL) trigger a predefined escalation protocol that may include daily PCT/CRP monitoring[20], empirical broad-spectrum antibiotics, and consideration for ultrasound-guided diagnostic aspiration or therapeutic drainage.

We emphasize that this algorithm represents a hypothesis-generating framework that requires prospective validation. Its implementation should be accompanied by rigorous outcome tracking to refine thresholds and ensure net clinical benefit. Nevertheless, we believe it offers a practical starting point for centers seeking to transition from reactive to proactive postoperative management.

CONCLUSION

The study by Gao et al[17] represents a significant advancement in the postoperative management of patients undergoing laparoscopic gastrectomy. It presents a robust, evidence-based rationale for augmenting traditional clinical judgment with structured, technology-enhanced monitoring. The synergistic use of dynamic transabdominal ultrasound-evaluating both the volume and internal architecture of fluid collections-and serial PCT measurements constitutes a powerful dual-modality framework for risk stratification.

For practicing surgical oncologists, the key message is unequivocal: POD 3 represents a critical decision-making window. A focused ultrasound examination at this time point, with meticulous assessment of the echotextural characteristics of any intraperitoneal fluid, yields highly valuable prognostic information. When combined with PCT levels, this imaging finding transforms clinical suspicion into quantifiable risk assessment. Pending validation from larger prospective trials, adopting a more proactive monitoring strategy based on these findings is clinically justifiable. Implementing routine ultrasound and PCT measurement on POD 3 for high-risk patients is a low-burden, high-yield intervention that aligns with the principles of modern surgical care-emphasizing not only technical excellence but also strategic foresight in safeguarding patient safety and optimizing recovery trajectories.

In summary, this research advocates a paradigm shift-from reactive diagnosis of established complications toward proactive prediction and prevention. It exemplifies how the thoughtful integration of accessible diagnostic tools can refine clinical practice, advancing the field toward the goal of truly personalized and pre-emptive surgical care.