Renal venous thrombosis in neonates. Initial and follow-up abnormalities.

Five neonates with renal venous thrombosis (RVT) were studied at the onset of the disease, and four have been followed up for from 24 to 32 months after the time of diagnosis. Reduced glomerular filtration (two of four cases) on follow-up occurred only in infants with bilateral abnormalities as shown by results of physical examination, urography, renal scan, and angiography. Results of contrast studies showed the similarity between resolved RVT and certain congenital renal abnormalities. Renal tubular defects (polyuria, acidosis, hyperkalemia) constituted the primary clinical abnormalities in one of the two infants with renal insufficiency. Although the prognosis of RVT after medical management has improved, the ultimate outcome is unknown; the possibility of unsuspected neonatal RVT should be considered during investigation of children with unilaterally or bilaterally small kidneys.