A 2 year old child with severe dehydration has sudden-onset Gross Hematuria with a unilateral flank mass. The most likely diagnosis is

Renal vein thrombosis (RVT) is the formation of a clot in the vein that drains blood from the kidneys, ultimately leading to a reduction in the drainage of one or both kidneys and the possible migration of the clot to other pas of the body. RVT is the Most common site of spontaneous thrombosis in newborn * 25% bilateral - 52-60% extend into the IVC * Presentation Hematuria, palpable flank mass, thrombocytopenia * Outcomes - 70% of affected kidneys irreversible atrophy - 20% hypeension; 3% chronic renal failure Reference: GHAI Essential pediatrics, 8th edition