Acute pancreatitis after pancreatoduodenectomy: A prospective study of diffusion-weighted magnetic resonance imaging, serum biomarkers, and clinical features

Background: Postpancreatectomy acute pancreatitis is challenging to diagnose and poorly characterized in its early phases. However, it represents the ideal target for novel therapeutic opportunities possibly gleaned from medical acute pancreatitis. This study aims to systematically investigate early radiologic, biochemical, and clinical features of postpancreatectomy acute pancreatitis. Methods: This was a prospective observational study of patients undergoing pancreatoduodenectomy from September 2019 to January 2021. Diffusion-weighted magnetic resonance imaging was performed on postoperative day 3. Serum pancreatic amylase and lipase were assessed daily until postoperative day 5. Postoperative serum hyperamylasemia and postpancreatectomy acute pancreatitis were defined based on the International Study Group for Pancreatic Surgery definition. Results: A total of 65 patients were enrolled according to the sample size calculation. Patients with postoperative serum hyperamylasemia and postpancreatectomy acute pancreatitis had significantly lower apparent diffusion coefficient values at diffusion-weighted magnetic resonance imaging but no macroscopic features consistent with acute pancreatitis. Subsequently, 21 patients (32.3%) underwent computed tomography imaging for clinical worsening, and 6 had radiologic features of acute pancreatitis. All these latter patients had postoperative serum hyperamylasemia and worse outcomes, characterized by local (postoperative pancreatic fistula: 83%) and systemic morbidity (sepsis: 66.7%). The postoperative serum hyperamylasemia incidence was 21.5% (n = 14), and postpancreatectomy acute pancreatitis occurred in 6 patients (9.2%), with 4 grade B (6.1%) and 2 grade C (3%). Conclusion: Postpancreatectomy acute pancreatitis is characterized by early serum hyperamylasemia and hyperlipasemia. Although pancreatic changes may appear at postoperative day 3 diffusion-weighted magnetic resonance imaging, its standard use has no impact on postoperative management. Macroscopic radiologic features appear later and correlate with worse clinical scenarios. This paper paves the ground for including postpancreatectomy acute pancreatitis in the spectrum of acute pancreatitis, promoting the transfer of treatment strategies for acute pancreatitis into managing postpancreatectomy acute pancreatitis.