Figure 1.

Congestion stages as defined by intrarenal venous flow patterns. Pulsed‐wave Doppler samples of renal congestion patterns in the interlobar renal vessel. The upward Doppler signal shows the intrarenal arterial flow, which is used to measure renal resistive index; the downward Doppler signal shows the venous flow, used to measure venous impedance index or renal venous stasis index. A, No congestion: continuous venous flow. B, Stage 1 congestion: pulsatile venous flow. C, Stage 2 congestion: biphasic venous flow. D, Stage 3 congestion: monophasic venous flow. D indicates diastole; S, systole; VII, venous impedance index.