Bilateral Native Renal Vein Thrombosis in a Liver and Kidney Transplant Recipient

Introduction: Renal vein thrombosis (RVT) is a rare condition predominantly linked to nephrotic syndrome, hereditary hypercoagulable disorders, malignancies, and sepsis in adults. The incidence of native RVT after simultaneous liver and kidney transplantation (SLKT) is unknown. In this case, we present an incidental finding of bilateral native kidney vein thrombosis in a liver and kidney transplant recipient. Case Description: A 44-year-old male received SLKT. Thirteen months post-transplant, bilateral native renal vein thrombosis extending into the inferior vena cava (IVC) below the diaphragm appeared on a CT scan during a preop workup for incisional hernia repair. The renal allograft was free of venous thrombosis based on the CT scan and a Doppler study. A focused investigation for the underlying cause of thrombosis ensued. The family history of thromboembolism was negative. Tests including Lupus anti-coagulant; anti-cardiolipin IgG and IgM; anti-beta-2 Glycoprotein IgG and IgM; factor V Leiden and prothrombin (20210G>A) mutations yielded negative results. Genetic mutations implicated in myeloproliferative neoplasm including JAK2 (V617F), Calreticulin (CALR Exon 9), and MPL mutations were not detected. Similarly, paroxysmal nocturnal hemoglobinuria was ruled out by flow cytometry. The function of the renal and liver allografts remained stable, and proteinuria was not detected. With apixaban treatment, a CT scan showed complete resolution of the bilateral native renal vein thrombosis after 3 months. Discussion: This case highlights the incidental finding of native RVT after SLKT, a pathology with an unknown clinical incidence. When found, it warrants a complete comprehensive workup for an underlying etiology. The most efficacious type and duration of anticoagualation is unknown, and this decision should be multi-disciplinary and collaborative with the patient.Bilateral RVT extending into the IVC with renal vein dilation (yellow arrows).