OBJECTIVES: Acute pancreatitis (AP) may lead to the development of pancreatic walled-off necrosis (WON) and vascular complications. We analyzed the frequency of vascular complications and their clinical impact in patients with WON. MATERIALS AND METHODS: The development of bleeding and splanchnic venous thrombosis (SVT) was assessed in a retrospective, single cohort of 290 patients undergoing invasive treatment for symptomatic WON. Bleeding was defined as nonprocedure-related requiring transfusion, embolization, or surgery, whereas SVT was defined as the presence of a thrombus in one of the splanchnic veins on contrast-enhanced computed tomography. RESULTS: In total, 78 patients (27%) developed 87 vascular complications. Forty-four patients (15%) developed SVT, 25 patients (9%) bleeding, and 9 patients (3%) developed both. At the time of the index intervention, 44 patients (83%) had already developed SVT, and only 7 episodes of bleeding had occurred (21%). Patients with bleeding had a greater need for intensive care unit treatment and their in-hospital mortality was higher than patients without bleeding (59% vs 38%, P = 0.003 and 38% vs 13%, P <
0.0001, respectively). CONCLUSIONS: Vascular complications are common in WON patients, but only bleeding is associated with increased morbidity and in-hospital mortality. Most SVT occur before an index intervention, while bleeding episodes primarily occur afterwards.