Hydronephrosis in the Fetus and Neonate: Causes, Management, and Outcome

Abstract

Hydronephrosis is one of the most commonly identified prenatal anomalies, and the severity may vary from mild to severe, depending on the underlying cause, many of which stem from disruptions in the formation of the renal collecting system. Permanent renal damage may occur if the condition progresses before birth, and in some cases, oligohydramnios may result in lung hypoplasia, a potentially fatal condition. Many cases resolve spontaneously before birth, but for those that do not, the additional prenatal evaluation can identify cases sufficiently severe to require fetal intervention to preserve renal function. The benefits of these interventions are not completely clear and must be balanced against the significant risks of the procedures and their sequelae as well as the questions that remain about long-term efficacy. For other cases, a process of further evaluation before and after birth is warranted, and factors such as cause, severity, and whether the condition is uni- or bilateral are used to formulate decisions about additional assessment and potential intervention. The long-term outcome of the common causes of hydronephrosis and the impact of each of these factors and medical and surgical intervention on this outcome are reviewed.