Pancreatic allograft thrombosis: Suggestion for a CT grading system and management algorithm

Abstract

Pancreatic allograft thrombosis (PAT) remains the leading cause of nonimmunologic graft failure. Here, we propose a new computed tomography (CT) grading system of PAT to identify risk factors for allograft loss and outline a management algorithm by retrospective review of consecutive pancreatic transplantations between 2009 and 2014. Triple‐phase CT scans were graded independently by 2 radiologists as grade 0, no thrombosis; grade 1, peripheral thrombosis; grade 2, intermediate non‐occlusive thrombosis; and grade 3, central occlusive thrombosis. Twenty‐four (23.3%) of 103 recipients were diagnosed with PAT (including grade 1). Three (2.9%) grafts were lost due to portal vein thrombosis. On multivariate analysis, pancreas after simultaneous pancreas–kidney transplantation/solitary pancreatic transplantation, acute rejection, and CT findings of peripancreatic edema and/or inflammatory change were significant risk factors for PAT. Retrospective review of CT scans revealed more grade 1 and 2 thromboses than were initially reported. There was no significant difference in graft or patient survival, postoperative stay, or morbidity of recipients with grade 1 or 2 thrombosis who were or were not anticoagulated. Our data suggest that therapeutic anticoagulation is not necessary for grade 1 and 2 arterial and grade 1 venous thrombosis. The proposed grading system can assist clinicians in decision‐making and provide standardized reporting for future studies.

Retrospective study on detection, treatment, and clinical outcome of graft thrombosis following pancreas transplantation

“…The proposed grading system of thrombosis by the Cambridge group is supported. Unfortunately, due to the retrospective nature of our study, the grading system was not incorporated in our database . Even though CT imaging in this study was inconclusive in 10–17% with regard to graft thrombosis, we do, however, believe that CT imaging should be part of routine follow‐up, following pancreas transplantation.…”

“…Unfortunately, no data on acute kidney injury (25% increase in eGFR or 44 lM increase in serum creatinine) were available in our database. However, CT imaging allows for early detection of sub-clinical partial thrombosis, which may be amenable for treatment [7,9]. This is supported by the finding that in 25% of the CT scans that were performed per protocol, some form of thrombosis was discovered.…”

“…All of these partial thrombosis were safely managed with unfractionated intravenous heparin, without any negative consequences . Another recent study proposed a CT‐based grading scheme for graft thrombosis, stating that not all graft thrombosis requires treatment . It is our aim to evaluate these findings by describing our experience regarding partial thrombosis.…”

Susceptibility‐directed anticoagulation after pancreas transplantation: A single‐center retrospective study

“…Thrombosis of the pancreatic allograft (PA) accounts for the majority of early nonimmune grafts loss, and up to 29% of grafts lost within the first 6 post‐transplant months . As one of the three traditional factors of Virchow's triad, the prothrombotic proclivity of diabetes and end‐stage renal disease plays an important role in the pathogenesis of graft thrombosis .…”

“…This hypercoagulability is due to excessive primary (ie, formation of a platelet plug) and secondary (ie, fibrin formation) hemostasis, coupled with hypofibrinolysis, a condition more commonly referred to as fibrinolytic shutdown (FS) . Reported incidences of PA thrombosis vary considerably, between 1% and 40%, but is generally described as 4‐8% . Sonography remains the primary imaging modality for PA surveillance, but the lack of a comprehensive thrombosis scoring system hinders improvement in thrombosis prevention and graft survival.…”