Calyx to parenchyma ratio in pelvi-ureteric junction obstruction

Objective To review the ultrasonography of patients who had undergone pyeloplasty for pelvi-ureteric junction (PUT) obstruction, and document the changes in calyceal distension and parenchymal thickness after pyeloplasty, to attempt to establish an additional prognostic indicator. Patients and methods Fifty-eight patients who underwent pyeloplasty for PUJ obstruction were assessed retrospectively. Pre- and postoperative ultrasonograms were analysed for both pyelocaliectasis, graded according to the Society for Fetal Urology criteria, and the ratio of the depth of calyces to the thickness of the parenchyma (C/P ratio). Patients underwent nuclear medicine renography before and 3 months after pyeloplasty. The results were analysed using the paired t-test, Kruskal-Wallis test, Spearman's correlation coefficient by rank test and the Mann-Whitney U-test. Results There was no significant difference in hydronephrosis grade before and after surgery (P<0.05) but there was a significant difference in the C/P ratios (P<0.01). There was no correlation between C/P ratios and the results of diuresis renography. Conclusion Hydronephrosis as measured by an estimate of pelvic volume is an insensitive marker of improvement after pyeloplasty. Reduced calyceal distension correlates well with other favourable prognostic indicators. Therefore, the C/P ratio may be an additional indicator of the appropriateness of surgical intervention, and should be the subject of further study.