Renal transplantation and the abnormal urinary tract

Pediatric renal transplantation into the abnormal urinary tract

Many children with end-stage renal disease have significant urinary tract problems other than irreversible loss of native kidney function. These significant other urinary tract problems, if not corrected prior to transplantation, may significantly increase recipient mortality, graft loss, and patient morbidity. These other urinary tract problems may cause hydroureteronephrosis in the transplanted kidney, lead to an increased incidence of graft rejection, be the source of sepsis after subsequent immunosuppression, and cause hypertension. In addition, pre-existing urinary diversion, large interabdominal masses, or previous cancer require specific pre-transplant management plans. Potential pediatric transplant recipients with other significant urinary tract problems can be classified according to three parameters; anatomical extent, pathology, and pathophysiology of the significant other problems. Particular attention must be paid to pre-existing lower tract problems. Strategy must be worked out pre transplant as to how the lower urinary tract is going to store, hold, and empty urine. The means for assessing the potential recipients and strategies and techniques for correcting pre-existing problems have been summarized in this article.

Loss of elasticity in dysfunctional bladders: urodynamic and histochemical correlation

To store adequate volumes of urine at low safe pressures an elastic bladder wall is required. We developed 2 new techniques to measure this ability in our urodynamic laboratory: pressure specific bladder volume, which measures the bladder capacity at a given pressure, and dynamic analysis of bladder compliance. Recently, morphometric and histochemical techniques have been used to determine the relative volume of connective tissue in the bladder wall and to measure the 2 major types (I and III) of collagen within the bladder wall. These methods quantitate 3 parameters of bladder ultrastructure: 1) relative volume of per cent connective tissue, 2) ratio of connective tissue to smooth muscle and 3) ratio of type III to type I collagen. These parameters have been shown to be abnormally elevated in patients with dysfunctional bladders compared to normals. The purpose of the study was to describe the ultrastructural changes that occur in the wall of dysfunctional bladders and to determine the ability of these new urodynamic techniques to detect reliably the clinical effect of these histological changes. The study included 29 consecutive patients with dysfunctional bladders necessitating bladder augmentation. All patients had upper tract changes and/or were incontinent despite treatment with clean intermittent catheterization and pharmacotherapy. Preoperative urodynamic evaluation included measurement of the total bladder capacity, pressure specific bladder volume and dynamic analysis of bladder compliance. Full thickness bladder biopsies were obtained from the dome of the bladders during augmentation. The per cent connective tissue and the ratio of connective tissue to smooth muscle were determined for all patients, and 4 unselected patients from this group had the ratio of type III to type I collagen determined. These histological results were compared to previously established normal values. All 29 patients had a decreased pressure specific bladder volume and dynamic analysis of bladder compliance, whereas 9 had a normal total bladder capacity. The per cent connective tissue was 35.19 +/- 2.84 and ratio of connective tissue to smooth muscle was 0.60 +/- 0.08 compared to normal values of 10.6 +/- 0.020 and 0.131 +/- 0.021, respectively (p < 0.05). Ratio of type III to type I collagen was also significantly elevated in the 4 samples analyzed (30.53 +/- 1.37 versus 24.00 +/- 2.50, p < 0.05). We conclude that poor storage function of poorly compliant bladders is secondary to an alteration in the connective tissue content of the bladder wall. Furthermore, these pathological ultrastructural changes are universally reflected by an abnormally low pressure specific bladder volume and dynamic analysis of bladder compliance. This strong association validates the use of these parameters and suggests that they are urodynamic indicators of a loss of elasticity in bladder wall.