Doppler ultrasonography in the early postoperative evaluation of renal transplants in children.

The renal ultrasonography (US) scans of 23 children who had recently undergone kidney transplantation were reviewed; the studies included Doppler US scanning of the arterial vessels at several levels. There were 43 studies for children whose postoperative course was normal; 16 studies were obtained during episodes of acute tubular necrosis and 21 during episodes of acute rejection. The upper limit of normal for the resistive index (RI) at the arcuate artery is higher (up to 0.79) for a pediatric renal transplant patient than for adults with normal kidneys, regardless of the age of the kidney donor. Therefore, elevation of the RI to 0.80 or higher or complete loss of diastolic flow always indicates a complication of transplantation. Abnormally high RI values were seen in patients with both acute tubular necrosis and acute rejection; however, the RI value as determined by US did not distinguish these two entities. In addition, in 7 cases of acute tubular necrosis and 12 of acute rejection the RI was normal (0.58 to 0.79).