Congential obstructive nephropathy gets complicated

Abstract

Most young children with end-stage renal failure are born with abnormal kidneys1,2, predominantly with renal dysplasia, a term describing a histopathologic spectrum featuring a block in normal differentiation (e.g., poor collecting duct branching and failure to generate glomeruli and nephron tubules) and aberrant differentiation (e.g., lineage switching to form smooth muscle and cartilage)2,3. The term "congenital obstructive nephropathy" describes kidney malformations associated with obstructed urinary tracts4. In many cases, lesions affect only one of the two renal tracts, and, in these cases, end-stage renal failure does not develop. Such lesions include atretic ureters associated with multicystic dysplastic kidneys and ureterocoeles associated with dysplasia of upper components of duplex kidneys. In other cases, when urinary flow impairment occurs later in gestation, or when obstruction is partial (e.g., pelvic-ureteric junction obstruction), renal damage is less profound, although fibrosis and atrophy can occur. On the other hand, when fetal urine flow is impaired bilaterally, the clinical implications are severe, with end-stage renal failure a possibility. In such cases the obstructing lesion is generally distal to the urinary bladder (e.g., posterior urethral valves), a lesion almost unique to males4. The latest epidemiologic data from the United Kingdom indicate that approximately 750 children are being treated for end-stage renal failure. Renal dysplasia without obstruction accounts for 22% of these individuals, while congenital obstructive nephropathy with posterior urethral valves accounts for another 14% (Personal communication, M. Lewis, Report of the Pediatric Renal Registry, 2002).