Renal vein thrombosis in utero: duplex sonography in diagnosis and follow-up.

Neonatal renal vein thrombosis (RVT) is a well-described entity which is traditionally associated with a variety of perinatal stresses. Prenatal RVT is much less commonly detected. We describe a case in which a screening obstetrical ultrasonogram detected a fetal renal abnormality which was incorrectly interpreted as a suspected neoplasm of the fetal kidney. Ultrasonographic examinations during the first week of life confirmed the diagnosis of RVT, and both gray-scale and Doppler techniques were used to follow the resolution of the thrombosis and the fate of the kidney.