[Renal vein thrombosis in the neonatal period].

Renal vein thrombosis is a rare disease, which most often occurs in the newborn, in premature babies with complicated deliveries, dehydration, septicaemia or congenital heart defects or in neonates delivered by diabetic mothers. Renal vein thrombosis is due to venous stasis secondary to haemoconcentration or decreased renal perfusion. The typical features are a palpable flank mass, microscopic haematuria, thrombocytopenia, leucocytosis and fever. Ultrasonographic examination shows an enlarged kidney with decreased echogenicity and loss of corticomedullary differentiation combined with hyperechoic streaks throughout the kidney. In Doppler sonography the obstruction of the peripheral veins causes a missing or even negative diastolic flow in the renal arteries. Intravenous pyelography and CT demonstrate missing or delayed excretion in the enlarged kidney. Usually the affected kidney becomes atrophic with calcifications of the renal parenchyma, the renal vein or the inferior vena cava. Therapy is symptomatic. The prognosis is dependent on the extent of the thrombus. In 25% of cases the affected kidney will improve or regain its normal function.