Portal Vein Thrombosis May Be More Strongly Associated With Islet Infusion Than Extreme Thrombocytosis After Total Pancreatectomy With Islet Autotransplantation

BACKGROUND Total pancreatectomy with islet autotransplantation (TPIAT) involves pancreatectomy, splenectomy, and reinjection of the patient's pancreatic islets into the portal vein. This process triggers a local inflammatory reaction and increase in portal pressure, threatening islet survival and potentially causing portal vein thrombosis. Recent research has highlighted a high frequency of extreme thrombocytosis (platelets ≥1000 × 109/L) after TPIAT, but its cause and association with thrombotic risk remain unclear. METHODS This retrospective single-site study of a contemporary cohort of 409 pediatric and adult patients analyzed the frequency of thrombocytosis, risk factors for thrombosis, and antiplatelet and anticoagulation strategies. RESULTS Of 409 patients, 67% developed extreme thrombocytosis, peaking around postoperative day 16. Extreme thrombocytosis was significantly associated with infused islet volumes. Thromboembolic events occurred in 12.2% of patients, with portal vein thromboses occurring significantly earlier than peripheral thromboses. Portal vein thromboses were associated with infused islet volumes and portal pressures but not platelet counts or other measures. Most thromboembolic events (82.7%) occurred before the postoperative day of maximum platelet count. Only 4 of 27 (14.8%) of portal vein thromboses occurred at platelet counts ≥500 × 109/L. Perioperative heparin was given to all patients. Treatment of reactive thrombocytosis using aspirin in adults and hydroxyurea in children was not associated with significantly decreased thromboembolic risk. CONCLUSIONS These results suggest that post-TPIAT thrombocytosis and portal vein thromboses may be linked to the islet infusion inflammation, not directly to each other, and further reducing this inflammation may reduce thrombosis and thrombocytosis frequencies simultaneously.