Post-operative acute pancreatitis after major pancreatic resections: from a clinical insight to an International Study Group of Pancreatic Surgery research project

Starting from an insight that emerged in the daily clinical practice, postoperative acute pancreatitis has become an increasingly recognized complication after major pancreatic resections, but its incidence and clinical impact, and even its existence quickly became a matter of debate. The aim of the project was to observe, describe, analyze, and eventually develop a universally accepted definition for standardized reporting and outcome comparison. The phenomenon was initially observed and described on a retrospectively collected series of consecutive major pancreatic resection. Results were then reproduced and confirmed on a prospectively collected series of patients. At this point, a comprehensive systematic review of the literature of post-operative acute pancreatitis and post-operative hyperamylasemia was carried out to obtain a complete picture of the available evidence. The phenomenon was deeply analyzed using the prospective series to identify specific characteristics able to give a unique definition. All data collected were shared among the members of the International Study Group of Pancreatic Surgery and, eventually, a universally accepted definition of post-pancreatectomy acute pancreatitis was reached. The whole project is developed in a series of six papers published on surgical journals from 2018 to 2021. In the final paper, the ISGPS defines PPAP as an acute inflammatory condition of the pancreatic remnant occurring in the setting of a partial pancreatic resection and initiated early in the perioperative period within the first 3 postoperative days. This pathophysiologic process can present various degrees of severity and several local and systemic complications, resulting in a deviation from the expected postoperative course. A sustained increase in serum amylase activity greater than the specific institutional upper limit of normal, which persists within at least the first 48 hours postoperatively, is necessary for the diagnosis. To be defined as PPAP, however, this condition needs to be confirmed by cross-sectional imaging and to be clinically relevant to the patient. The presence of a consensus definition and grading system will serve as a foundation to open new perspectives in identifying diagnostic and prognostic criteria for PPAP and recognizing all the complications associated with this condition. Hopefully, treatments to decrease the occurrence or the burden of complications related directly to PPAP will then be established.