Renal dysplasia in children with posterior urethral valves: a primary or secondary malformation?

Abstract

Routine prenatal ultrasound examination of the urogenital tract is of importance in patients with posterior urethral valves (PUV), because the renal function and long-term prognosis of these patients depend on early diagnosis and subsequent therapy. Opinion is divided as to whether the often-observed association of PUV with renal dysplasia represents a primary malformation or a secondary pathology caused by recurrent infections. These aspects should have an influence on therapeutic consequences and optimal timing of therapy in order to preserve long-term renal function. The histology of kidney specimens from 13 children with PUV who underwent nephrectomy was reviewed to attempt to differentiate between primary dysplastic malformations and secondary pathologies. Clinical data were analyzed and compared with the histologic findings. The average age at nephrectomy was 29 months (range 3-158 months). Approximately 80% of the specimens showed primary dysplastic malformations (mesenchymal or fetal cartilage tissue or dysplastic glomeruli and tubuli) in the presence of well-developed renal parenchyma. All specimens showed secondary pathologies such as renal-cortical atrophy, interstitial fibrosis, and interstitial-nephritis atrophy. The histologic evidence of well-differentiated renal parenchyma in concurrence with dysplastic parenchyma makes infravesical obstruction as the only cause of renal alterations in patients with PUV questionable. This coincides with the fact that organogenesis of the kidney is terminated at the 12th gestational week and secondary renal damage is irreversible at the 20th gestational week, but prenatal urinary diversion of the upper urinary tract is feasible in the 20th gestational week at the earliest. These facts must be taken into account when considering intrauterine urinary diversion.

Posterior Urethral Valves: Prenatal Diagnostic Signs and Outcome

“…The high proportion of nonfunctioning kidneys (42%) in our study refl ects the experience of other authors [16] , even though no reliable evidence could be obtained to show that the PUVs were the sole causes of dysplasia and severe impairment of the renal function. The high proportion of bilateral renal damage caused by urethral valve disease has also been confi rmed elsewhere.…”

Renal transplantation in children with posterior urethral valves

“…Patients with posterior urethral valves (PUV) are at high risk of end-stage renal disease (ESRD) [1,2] due to the impact of obstructive uropathy on the renal parenchyma and urinary tract and the resulting bladder dysfunction, vesicoureteral reflux, and urinary infections, but especially due to intrauterine parenchymal dysplasia secondary to urinary tract obstruction [3,4]. This possibility of ESRF manifests in early stages of life in some patients, requiring renal transplantation (RT) to be performed in childhood.…”

A novel heterozygous GLI2 mutation in a patient with congenital urethral stricture and renal hypoplasia/dysplasia leading to end-stage renal failure

“…Second, posterior urethral valve (PUV), in which the bladder outflow is obstructed, is one of the most common causes of end-stage kidney disease in childhood. Animal models of PUV have demonstrated varieties of renal dysplasia and reductions in the nephron number [10,11]. Finally, both mechanical and humoral effects have been seen in rat models of obstructed kidney.…”