Duplex Doppler examination of renal allografts in children: correlation between renal blood flow and clinical findings.

We reviewed the diastolic blood flow (DBF), pulsatility index (PI), and resistive index (RI) in 211 duplex Doppler ultrasound examinations of 63 pediatric renal transplant recipients. We correlated our findings with the clinical diagnosis, independently determined at the time of ultrasound examination. DBF, evaluated in 202 examinations, was found to be decreased, absent, or reversed in acute rejection (kappa = 0.4, p < 0.01) and acute tubular necrosis (ATN) (kappa = 0.3, p < 0.01). The PI and RI were evaluated in 87 and 78 ultrasound examinations respectively. The range of normal PI and RI values in recipients between six and 18 years of age were similar to those reported in adults. However, normal PI and RI values were somewhat higher in recipients less than six years of age who had received adult donor allografts. Overall, the PI was greater than 1.5 in acute rejection (kappa = 0.3, p < 0.05) and ATN (kappa = 0.3, p < 0.01), but not in chronic rejection (kappa < 0, p = NS). The RI was greater than 0.7 in chronic rejection (kappa = 0.3, p < 0.05) and ATN (kappa = 0.3, p < 0.05), but not in acute rejection (kappa = 0.03, p = NS). We conclude that the PI and RI vary in pediatric recipients of renal allografts and are not associated with a specific clinical diagnosis.