Background: Changes in renal arterial Doppler flow may identify parenchymal disease, but in newborns knowledge of normal physiological parameters is a prerequisite for correct interpretation.
Objective: To evaluate renal blood flow in healthy newborns by means of Doppler US.
Materials and methods: On the fourth day of life we examined 100 normal term newborn infants (200 kidneys). Blood flow in the central renal arteries was compared with that in the intraparenchymal arteries. Maximum systolic velocity ( V(max)), end-diastolic velocity ( V(ed)), mean flow velocity ( V(mean)), resistive index (RI) and pulsatility index (PI) were assessed.
Results: All parameters were significantly higher in the central renal arteries than in the intraparenchymal arteries (RI 0.78+/-0.07 vs 0.62+/-0.05, P<0.0001; PI 1.84+/-0.52 vs 1.09+/-0.18, P<0.0001).
Conclusions: Physiological data are presented that are necessary for the correct interpretation of neonatal Doppler US.