Doppler ultrasound in the diagnosis of vascular occlusion in renal transplantation..

In renal transplantation vascular occlusion is usually diagnosed too late for remedial surgery to be successful. A method of continuous monitoring of renal blood flow would provide evidence of a vascular problem and a chance of saving the graft. In this study directional Doppler ultrasound has been used to investigate arterial stenosis and venous outflow obstruction in a canine autograft model, using the pulsatility index (PI). The results demonstrate increasing PI with venous outflow block (P less than 0.005 at stenoses greater than 88% of venous diameter) and a fall in PI accompanying a progressive reduction in arterial inflow (P less than 0.001 at stenoses greater than 78% of arterial diameter). Identical results were achieved with both handheld and indwelling probes. The changes in the audible Doppler signal have a characteristic quality and the insertion of an indwelling Doppler probe offers a potential means of monitoring allograft blood flow in the immediate postoperative period and differentiating between venous and arterial obstruction.