Accuracy of sonographic volume measurements of kidney transplant

Sonographic measurement of renal volume is one of the parameters used in the diagnosis of renal transplant dysfunction and in follow-up of patients with renal transplant. The aim of this study was to compare the prolate ellipsoid formula with a new formula in calculating the volume of a transplanted kidney.

The renal volumes in 24 patients with a stable renal transplant were determined sonographically with the ellipsoid formula and via helical CT with the voxel-count method, which is the gold standard. A new formula that uses renal length and the cross-sectional area at the maximum transverse section has been evaluated in a small series of transplanted kidneys.

Renal volume was underestimated with the sonographic ellipsoid formula and the new formula. The new formula yielded the lowest underestimation of the mean renal volume, and the measurements obtained with it were not significantly different from those obtained with CT.

The use of sonography is appropriate for accurate calculation of renal volume, and the new formula that uses only 2 ultrasound parameters best represents the volume of a renal transplant.