Background: The aim of this study was to evaluate the impact of the level of neck transection on clinically relevant postoperative pancreatic fistula (CR-POPF) after standard pancreaticoduodenectomy (PD) with pancreaticojejunostomy.Method: A total of 195 patients with an early postoperative CT scan were retrospectively analyzed and divided into 2 groups (CR-POPF and No CR-POPF) in order to seek potential risk factors for CR-POPF. We focused our analysis on the relationship between CR-POPF and the level of neck transection, defined by measuring the distance between the left side of the portal vein and the remnant pancreatic stump on the postoperative CT scan.Result: CR-POPF occurred in 58 out of 195 PD (29.7%); grade B (17%) and grade C (12.7%). The Clavien-Dindo ≥ 3 morbidity rate was 33% (65/195) and the mortality rate was 2.5% (5/195). Multivariate analysis indicated that a 'right-sided' level of neck transection (P = 0.007), a firm pancreatic texture (P = 0.001), and a PD for non-pancreatic ductal adenocarcinoma histology (P = 0.032) were independent risk factors for CR-POPF. A full neck resection with systematic transection ≥7 mm at the left side of the portal vein seems to prevent CR-POPF harboring a protective effect (OR 0.056; 95% CI 0.003 to 0.978; P = 0.039).Conclusion: Here we further consolidate the concept describing the pancreatic neck as a vascular watershed, showing that a long remnant pancreatic neck could be an independent risk factor for CR-POPF after PD (NCT03850236).Trial registration number and agency: The present study was approved by our local ethics committee and was declared on ClinicalTrials.gov (ID: NCT03850236).