Comparison between doppler ultrasound resistive index, serum creatinine, and histopathologic changes in patients with kidney transplant dysfunction in early posttransplantation period: A single center study with review of literature

Abstract

To determine the relationship between resistive index (RI) measured by Doppler ultrasound, serum creatinine (SCr), and histopathological changes on biopsy during kidney trans- plant dysfunction in early postoperative period, we studied 47 kidney transplant patients; 61% of the patients had acute transplant rejection, 19% had acute tubular necrosis, 4% had calcineurin inhibitor toxicity, 11% had normal morphology in biopsy, and 5% had changes compatible with pyelonephritis. None of the study patients had interstitial fibrosis or tubular atrophy on biopsy. We found that the sensitivity and specificity of RI in diagnosing transplant dysfunction was highly variable depending on the selected cutoff value. Sensitivity of RI decreased and its specificity increased with increasing the RI thresholds. Using an RI threshold of 0.7 resulted in a high sensitivity of 78% at a cost of very low specificity 40%, whereas using an RI threshold of 0.9 resulted in 100% specificity at a cost of very low sensitivity 16%. Acceptable specificity was only achieved at the expense of very low sensitivity, resulting in poor utility of RI as a screening tool for dysfunction. We found that there were no significant differences in the mean RI value between patients with and without biopsy-proven transplant dysfunction. However, we found a significant correlation between SCr value and RI of 0.383, P = 0.007.