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BACKGROUND

Renal venous thrombosis (RVT) is a condition in which a thrombus forms in the venous drainage system of one or both kidneys. The thrombus can extend from the arcuate renal vessels through the renal vein and as far as the vena cava1 (Figure 117-1). The condition is also referred to as renal vein thrombosis, but because the thrombus often extends beyond the anatomic boundaries of the renal vein both proximally and distally, the term renal venous thrombosis is preferred.2

FIGURE 117-1.

Venous anatomy of kidney. (Reproduced with permission from Mescher AL. Junqueira’s Basic Histology: Text and Atlas. 13th ed. McGraw-Hill Education; 2013. Fig 19-3.)

PATHOPHYSIOLOGY

In the pediatric population, the majority of cases of RVT occur in the neonatal period and RVT is the most common spontaneous thromboembolic event in this population.2 Newborns are at risk for elements of Virchow’s triad (hypercoagulability, stasis, and vessel wall injury), which can lead to venous thrombosis. Newborns have increased renal vascular resistance and therefore relatively diminished renal blood flow.1,2 Polycythemia, either idiopathic or associated with maternal diabetes mellitus or congenital heart disease, leads to sludging and stasis in the small vessels.3 Similarly, acute blood loss, shock, asphyxia, or sepsis can result in hypovolemia and vessel wall injury.4 Infants with traumatic delivery are at higher risk for RVT than are those delivered uneventfully.1 In addition, central venous catheters, which are frequently needed in the neonatal period, are a well-documented risk factor for venous thrombosis.3

RVT occurs less commonly in older infants and children. When it does, there is likely a predisposing condition, and RVT is often triggered by a hyperosmolar state.4 For example, patients with severe dehydration (e.g. gastroenteritis) have decreased renal blood flow and hemoconcentration, which can increase the risk of thrombus formation.5 Similarly, radiologic procedures using hyperosmolar intravenous contrast agents can lead to RVT.2 Healthcare providers should have a high index of suspicion for RVT in patients with hypercoagulability due to an underlying condition (e.g. cancer, trauma, burns, surgery, congenital heart disease, nephrotic syndrome, pregnancy, lupus) or inherited thrombophilia (e.g. factor V Leiden, homocystinuria, prothrombin mutation).1,4,5 In patients with nephrotic syndrome, a hypercoagulable state is induced due to proteinuria. The loss of protein leads to a decrease in osmotic pressure, which triggers increasing platelet number and aggregation as well as a reduction in coagulation inhibitors. Certain medications, such as oral contraceptives and steroids, can also cause hypercoagulability.5 Rarely, trauma can lead to RVT, which may be associated with concurrent renal arterial thrombosis.5 Children with renal transplants are at risk for RVT, particularly if they are treated with cyclosporine.5

CLINICAL PRESENTATION

RVT classically presents with macroscopic hematuria and ...

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