Assessing the role of upside-down (inverted) renal allografts in pediatric kidney transplantation: a propensity-score matched analysis.

OBJECTIVE: To evaluate the implications of inverted (upside-down) kidney configuration in pediatric renal transplantation employing a comparative analysis with at least 1-year follow-up. METHODS: Patients who underwent kidney transplantation at our institution between January 2011 and June 2021 were reviewed. Patients who had an inverted renal transplant were propensity-score matched (PSM) in 1:2 ratio with those who had traditional orientation transplant. The outcomes assessed included delayed graft function (DGF), urine leak, lymphocele, rejection, allograft calculus, ureteric stricture, and nadir creatinine. RESULTS: A total of 24 patients with inverted orientation were identified. Following PSM, 41 patients were matched, with exclusions due to incompatible propensity scores. Baseline characteristics were appropriately matched, and no significant differences were noted between the two groups. There were no differences in: delayed graft function (0/24 vs. 3/41, p = 0.290), urine leak (3/24 vs. 2/41, p = 0.350), lymphocele (2/24 vs. 4/41, p = 1.000), rejection (3/24 vs. 5/41, p = 1.000), graft calculus (2/24 vs. 0/41, p = 0.133), and ureteric stricture (0/24 vs. 2/41, p = 0.527). The two cases of renal calculus seen in the inverted transplant group occurred on post-operative day 13 and 1584, both were managed without complications. There was no difference in nadir creatinine (median 34umol/L IQR23-57 vs. 35 umol/L IQR 20-50, p = 0.624) or time to nadir creatinine (8 days IQR 6-12 vs. 8 days IQR 7-28, p = 0.315). CONCLUSION: Inverting a renal allograft does not appear to significantly contribute to increased risk of post-operative adverse outcomes. When aiming to achieve the best anatomical placement to secure a comfortable vascular anastomosis, inverting the allograft should be considered.