Evaluation of the resistive index (RI) for the diagnosis of acute renal rejection in renal allografts from the same donor.

PURPOSE

To investigate the importance of the resistive index (RI) in the diagnosis of acute renal rejection, compared with the RI of the twin kidney from the same donor, transplanted in two different patients.

MATERIAL AND METHODS

From January to December 2000, we studied retrospectively 25 pairs (50 patients) of renal allografts from the same donor considering the RI obtained with by eco color-Doppler ultrasound, daily diuresis and renal function (serum creatinine level) in the first six days following surgery. Improvement of diuresis and renal function after corticosteroid therapy was considered the gold standard for the diagnosis of acute rejection.

RESULTS

Medical complications (acute renal rejection) in the first six days were occurred in three cases, two in the first transplanted kidney as first and one in the second; all three cases showed disappearance of the diastolic waveform component. Considering a RI variation >0.15 with respect to the initial value, the sensitivity, specificity and diagnostic accuracy in the Doppler diagnosis of acute rejection were 100%, 97.1% and 97.3% respectively, with a prevalence of 7.8%. There were no statistically significant correlations between the RI variation of the renal transplant and the twin kidney from the same donor.

DISCUSSION AND CONCLUSIONS

Doppler ultrasound is an important diagnostic tool in the detection of medical complications in the immediate postoperative period and during renal transplant follow-up. RI analysis, when studied serially and in the right clinical settings, allows an early diagnosis of renal rejection with high sensibility and specificity.