**1. Introduction**

Congenital obstructive nephropathy is the leading cause of pediatric chronic kidney disease (CKD). Consequently, it engenders a tremendous societal burden in terms of morbidity and mortality and in health care expenses over the lifespan of affected patients. The challenges clinicians face in the diagnosis, prognosis, and treatment of congenital obstructive nephropathy illustrate the utility of developing effective experimental models for the study of this complex disease process. In this review, we characterize congenital obstructive nephropathy with its myriad causes and manifestations, outline current standards of diagnosis and care, and discuss experimental animal models with relevance in unraveling clinical conundrums and molecular mechanisms of this important renal disease.

Congenital obstructive nephropathy is a complex process of pathologic changes in kidney development and function that arise when antegrade urine flow is impaired beginning *in utero*. The term *congenital obstructive uropathy* is frequently used to describe this condition. However, every urologic obstruction – whether anatomic, mechanical, or functional – should be approached with the knowledge that obstruction can affect the kidneys. For this reason, we prefer the term *congenital obstructive nephropathy.*

Intrinsic anatomic obstructions may occur in isolation or accompanied by other pathology such as renal hypodysplasia. Functional obstructions also occur, which may be transient and self-resolving, or chronic with potentially profound consequences on renal function. Although the etiologies of congenital obstructive nephropathy are myriad, any restriction of urine flow has the potential to produce hydronephrosis, altered renal development, and progression of CKD. This direct link between obstructed urine flow and abnormal kidneys represents a central paradigm of urogenital pathogenesis that has far-reaching implications (Woolf & Thiruchelvam, 2001).
