Monitoring renal allograft rejection with duplex sonography

Thirty‐six renal allograft recipients were monitored by serial duplex Doppler ultrasound studies post‐transplant and during early rejection. A separate reproducibility study demonstrated no significant interor intra‐operator variability in measurements of resistive index of an interlobar artery (RI) (2.1% [1.5%] and 3.2% [2.3%] respectively, mean [standard error] of coefficients of variance). Twenty‐one patients had rejection within 3 weeks of transplantation. These grafts showed greater overall rises in the RI, from day 2 to day 5 post‐transplant, than the grafts which had no rejection. Eleven of the 21 patients required more than one course of methyl‐prednisolone for persistent or recurring rejection. These grafts had higher RI on the day rejection was diagnosed (81 [7.3], median [interquartile range]) compared with the remaining 10 patients (68.6 [8.7]). The 11 grafts with persistent rejection had higher RI (p< 0.005, Mann‐Whitney U‐test) on day 2 post‐transplant (76 [3.9]) compared with the 10 grafts successfully treated with a single course of methyl‐prednisolone (63.2 [10.9]). This study demonstrates that grafts with an RI of greater than 70 on day 2 post‐transplant are likely to have rejection requiring additional treatment (sensitivity —100%, specificity –80%). These patients may be candidates for earlier or alternative antirejection therapy.