Renal Vein Thrombosis: A Narrative Review.

Renal venous thrombosis (RVT) is a location of unusual-site venous thromboembolism. RVT occurs more commonly in males, and shows a bimodal age distribution, with a neonatal and adult peak. Abdominal malignancies and nephrotic syndrome are prominent risk factors in adults, whereas hypotension, birth asphyxia, sepsis, umbilical venous catheters and prematurity are the predominant causes in children. The most common symptoms of RVT include abdominal pain and macroscopic haematuria. A palpable abdominal mass is often observed in neonates, while antenatal RVT may present with signs of foetal distress. Bilateral RVT can lead to acute renal failure. Anticoagulation is the cornerstone of treatment, traditionally with unfractionated heparin, low molecular weight heparin and vitamin K antagonists, although recent evidence is emerging on the use of the direct oral anticoagulants in selected RVT patients. Endovascular procedures (e.g., local thrombolysis or mechanical thrombectomy) are usually reserved for more severe cases, such as bilateral acute RVT causing kidney dysfunction. Outcome data show variability in mortality rates, with some adult cohorts reporting high mortality linked to underlying malignancies and other comorbidities. In paediatric cohorts, mortality is low, but RVT can lead to long-term complications, including kidney atrophy, kidney dysfunction and hypertension. This narrative review aims to synthesise the current evidence on RVT, with a particular focus on anticoagulant prophylaxis and treatment, and clinical outcomes in adult and paediatric populations.