Introduction and Objectives: Congenital renal hypoplasia/dysplasia (CRH) is the most common cause of end stage renal disease (ESRD) in patients who undergo kidney transplantation (KTx) at a young age in Japan. In some cases of CRH, bladder capacity is large and disproportionate to their physique. Although patients with true neurogenic bladder may require intermittent self-catheterization (CIC) or urinary tract diversion to protect graft function after KTx, few patients need to undergo these procedures in our experience. In this study, we evaluated the voiding function as well as the graft function in patients with CRH after KTx, especially in cases with abnormality of bladder capacity.
Methods: Among 310 patients who underwent KTx between 1985 and 2017 at Kobe University, CRH was the primal renal disease of ESRD in 26 patients. Bladder capacity and volume of residual urine after voiding (RU) were assessed preoperatively by voiding cystourethrography (VCUG). We defined flaccid bladder (FB) as the maximum desire to void (MDV) (mL) / body surface area (BSA; m²) >300 (mL/m²). The patients with RU in VCUG underwent urodynamic study (UDS). Postoperatively, we measured RU by ultrasonography at least 3 times and the mean value was used in this study. We also evaluated estimated glomerular filtration rate (eGFR; ml/min/1.73m²) by Japanese fomula and the analysis of urine sediment (Ux) at 3 months after KTx.
Results: Overall, 7 (27%) patients, including 5 women and 2 man, met the inclusion criteria for FB. The median age of the patients at the time of KTx was 11 years (7-43). Preoperative median MDV was 250 mL (range, 200-400), median MDV/BSA 302 mL/m² (range, 300-337), and median RU 0 mL (range, 0- 150). One patient had Grade 1 VUR, 1 patients had Grade 3 VUR, and 1 patient, Grade 4. Two patients with RU underwent UDS. Although both of these 2 patients had very weak sense of micturition after saline > 500 mL was injected in the bladder, the compliance of their bladder wall was good and observed no RU in UDS. All patients underwent KTx with the informed consent about the possibility of need to perform CIC if they had RU post-operatively. Patients with Grade 4 VUR also underwent nephrectomy simultaneously with KTx. All patients were indicated of schedule urination after removal of urinary catheter. Median RU was 3 mL (range, 0-49) after KTx and no patients required CIC. Ux was normal at 3 months follow-up in all cases; and median eGFR was 68.4 mL/min/1.73 m² (range, 54.3-92.9).
Conclusion: Although some of the patients with CRH who undergo KTx had bladder capacity abnormality, few patients need CIC with adequate indication of scheduled urination after KTx.