Acute renal vein thrombosis in renal allografts: detection with duplex Doppler US.

Renal allograft recipients were routinely monitored by means of duplex Doppler ultrasound. In a 20-month survey period, four instances of acute renal vein thrombosis were detected among 75 patients. All episodes occurred within the first 3 postoperative days. The examinations disclosed peaked, abruptly dropping systolic frequency shifts and retrograde plateaulike frequency shifts during diastole at the level of the main renal artery and its proximal branches. A venous Doppler signal could not be recorded. The findings are interpreted as indicating renal impedance exceeding diastolic pressure with nonpropulsive blood flow within the arterial vasculature.