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Renal vein thrombosis (RVT) is the occlusion of the renal vein by a thrombus, leading to renal venous congestion, reduced renal perfusion, and potential renal ischemia or infarction.

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It may occur acutely or chronically, unilaterally or bilaterally, and may involve native or transplanted kidneys.

Etiopathology

Predisposing Factors

A. In Adults

• Nephrotic syndrome (most common cause, especially membranous nephropathy)
• Hypercoagulable states:
  • Antiphospholipid syndrome
  • Oral contraceptives
  • Malignancy (especially renal cell carcinoma, which may extend into the renal vein/IVC)
  • Factor V Leiden, protein C/S deficiency, antithrombin III deficiency
• Dehydration (especially in postoperative or critically ill patients)
• Trauma or surgery
• Renal transplantation
• Idiopathic (rare)

B. In Neonates and Infants

• Dehydration, sepsis, maternal diabetes, birth asphyxia, or umbilical vein catheterization.

Pathophysiology

• Thrombus formation → obstruction of renal venous outflow → increased venous pressure → renal congestion → decreased renal blood flow and glomerular filtration.
• If prolonged, it causes cortical ischemia, tubular necrosis, and possible renal infarction.
• Collateral venous channels may develop in chronic cases.

Clinical Features