Analysis of Different Post-Operative Hyperamylasemia Criteria for Defining Post-Pancreatectomy Acute Pancreatitis After Distal Pancreatectomy—A Retrospective Single-Center Study

<b>Background/Objectives</b>: The International Study Group for Pancreatic Surgery has recently defined post-pancreatectomy acute pancreatitis (PPAP), stating that sustained postoperative hyperamylasemia (POH) for at least 48 h is a pivotal criterion. However, the clinical relevance of POH and PPAP following distal pancreatectomy remains uncertain. This study compares two PPAP definitions differing in POH criteria. <b>Methods</b>: We retrospectively analyzed all patients who consecutively underwent distal pancreatectomy at our institution (2010-2023). PPAP diagnosis required clinical symptoms, characteristic CT findings, and either sustained POH ≥ 48 h (standard group) or transient POH less than 48 h (modified group). Outcomes were compared between definitions. <b>Results</b>: Among 207 patients included, in the standard group, PPAP was diagnosed in 12 (5.8%), and in the modified group in 27 (13.0%) patients. Independent of the applied POH criteria, PPAP was associated with the occurrence of clinically relevant postoperative pancreatic fistulas (standard: 66.7% vs. 23.7%; <i>p</i> < 0.001; modified: 44.4% vs. 23.7%; <i>p</i> = 0.027). Post-pancreatectomy hemorrhage and major complications (Clavien-Dindo grade ≥ III) were also significantly more frequent in patients with PPAP. This was mirrored by a significantly longer length of stay and higher costs. However, in the standard group, PPAP more often resulted in pancreas-specific and major complications compared to the modified group. Of note, in the standard group, only 50% of patients with POH progressed to PPAP, and one-third of patients suffering from PPAP did not develop harmful sequelae. <b>Conclusions:</b> PPAP is an uncommon, however clinically relevant complication following distal pancreatectomy that is better captured using the standard POH definition. Still, further stratification is needed to aid in the prediction of the clinical course.