Pancreatic surgery with en bloc venous resection and reconstruction is becoming increasingly common in the current era of expanding neoadjuvant oncologic therapies and advanced surgical techniques for patients with more anatomically complex tumors. However, patients who have alterations in their venous outflow are at increased risk for postoperative portomesenteric venous stenosis and/or thrombosis. Cross-sectional imaging for postoperative surveillance, including multiphase CT or MRI, is critical for recognizing portomesenteric venous complications and thus implementing early intervention and preventing complications related to portomesenteric venous hypertension. Hypertension-related complications include ascites, variceal or gastrointestinal bleeding, postprandial abdominal pain, intestinal edema, protein-losing enteropathy, malabsorptive diarrhea, and splenomegaly. Percutaneous transhepatic, transsplenic, and transjugular portomesenteric interventions, including venoplasty, stent placement, and thrombectomy or thrombolysis, are safe and effective options for restoring patency to the portomesenteric venous system. Preintervention CT or MRI and diagnostic catheter venography are important for procedural planning, while postintervention CT or MRI surveillance is critical for detecting recurrent stenosis or thrombosis, or de novo portomesenteric venous disease. Online supplemental material is available for this article. ©RSNA, 2020.