Post written by Giuseppe Vanella, MD, PhD, from San Raffaele Hospital, Vita-Salute San Raffaele University, Milan, Italy.

When dealing with symptomatic or infected peripancreatic fluid collections (PFCs), EUS-guided drainage has become the standard of care. In about one-half of cases, drainage alone will be enough to solve the issue. Yet, a fraction of patients will require further interventions, such as direct endoscopic necrosectomy, additional drainage tracts, or percutaneous/surgical rescue, following the so-called “step-up approach.”

Until now, a simple, reliable, and broadly applicable predictive tool to identify these high-risk patients was missing. Most available evidence came from retrospective studies focusing only on walled-off necrosis and the use of lumen-apposing metal stents, often overlooking other types of collections and alternative stenting strategies.

Our study stemmed from a prospective registry enrolling all consecutive patients requiring EUS-guided PFC drainage in a tertiary referral center to evaluate independent predictors of step-up to additional procedures. We assessed the role of factors previously explored in retrospective literature, but we especially focused on the recently available Quadrant-Necrosis-Infection (QNI) score, developed by colleagues at Mayo Clinic.¹ Incorporating necrosis extent, number of abdominal quadrants involved, and presence of infection, the score stratifies PFCs into low- and high-risk categories. However, it had yet to be prospectively validated.

We prospectively enrolled 70 consecutive patients with PFCs, including walled-off necrosis, pseudocysts, and postsurgical collections. About 40% were treated with lumen-apposing metal stents, and the rest with double-pigtail plastic stents. The overall treatment results were encouraging: technical success was 100% and clinical success 93%, with negligible recurrence. However, 36% of patients required step-up procedures (mostly necrosectomy), as drainage alone was insufficient.

Two factors emerged as independent predictors for this more-complex treatment course: the classification in the QNI high-risk group and (independently) necrosis extent greater than 60%. Interestingly, collection size alone and microbiologically proven infection were not predictive.

We also compared necrosis assessment by radiology (CT/magnetic resonance imaging) and EUS. Although interobserver agreement within each modality was excellent, between-modalities agreement was low, as EUS tended to identify more-extensive necrosis than radiology and better predicted a more-complex disease course. This supports the role of real-time EUS assessment in guiding decisions such as stent type, timing of necrosectomy, or early adoption of additional step-up procedures.

Looking ahead, our findings confirm the prognostic value of the QNI score and suggest greater emphasis on necrosis extent (≥60%). Larger multicenter studies will be key to evaluate the real-world clinical impact of this stratification, potentially informing more-personalized strategies, guiding decisions on centralization to high-volume centers, influencing the hospitalization regimen, anticipating longer hospital stay, and prompting earlier access to secondary interventions when needed.

Graphical abstract

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1. Baroud S, Chandrasekhara V, Storm, AC, et al. Novel classification system for walled-off necrosis: a step toward standardized nomenclature and risk-stratification framework. Gastrointest Endosc 2023;97:300-8. ↩︎