Noninvasive surveillance of allografted kidneys by ultrasonic duplex scanning

Over a one-year period 1,000 duplex Doppler evaluations were performed in 70 patients submitted to kidney transplantation for end-stage renal failure. Duplex monitoring was performed to evaluate transplant status from hemodynamic patterns of the graft arteries. A duplex scanner with a 3.75 MHz sector transducer was used; pulsed Doppler was utilized to detect blood flow velocities in the main renal, segmental, interlobar and arcuate arteries. Arterial signals were quantified through a pulsatility index (PI). Three cases of acute rejection (AR), 9 cases of chronic rejection (CR), 2 cases of cyclosporine nephrotoxicity (Csa Tox), and 4 cases of acute tubular necrosis (ATN) were recognized and biopsy proved. At each arterial site PI values of normally functioning allografts were lower than 1.5; AR patients showed PI values ranging from 1.7 to 3.1, promptly lowered by immunosuppressive treatment. CR patients had a spectrum of PI from 0.5 to 3.1. Patients with Csa Tox and ATN showed in all the explored sites normal arterial signals and thus normal PI values. PI variations reflect even slight blood flow reductions due to immunologically mediated increases in intrarenal arterial resistances. Duplex sonography of allografted kidneys shows great diagnostic attitudes in the noninvasive characterization of transplant malfunction.