Ureteropelvic junction obstruction: diagnosis and management.

PURPOSE OF REVIEW: Ureteropelvic junction obstruction (UPJO) is the most common cause of prenatally diagnosed hydronephrosis. Although associated with obstruction of the kidney, the natural history is variable, ranging from spontaneous resolution to progressive loss of function over the first few years of life. As a result, the optimal evaluation strategy and indications for treatment have not been well defined. The purpose of this article is to review recent literature focused on the prenatal and postnatal evaluation of infants with prenatally diagnosed hydronephrosis suspicious for UPJO. RECENT FINDINGS: Recent studies have focused on the effect of the urinary tract dilation (UTD) ultrasound classification system, as well as use of magnetic resonance imaging both prenatally and postnatally to stratify the risk of infants with prenatally diagnosed hydronephrosis to develop renal impairment or undergo surgery. Additionally, urinary biomarkers have been identified as a potential noninvasive alternative to diuretic renography in identifying infants with clinically significant UPJO. SUMMARY: Although continued work is needed to develop clear guidelines for evaluation and treatment and to better define long-term outcomes, these studies offer novel approaches to improve the care of these patients.