Antenatal hydronephrosis: Assessment and management

Antenatal hydronephrosis (ANH) is a common finding on prenatal ultrasound that can be a sign of a variety of urologic conditions.Most cases of ANH are mild to moderate with the most common cause being transient physiologic dilation, which usually is of no clinical significance. However, there are some infants who have a history of ANH (usually severe) who are at increased risk for febrile urinary tract infections, undergo surgical intervention, and develop chronic kidney disease. It is useful to have an understanding of the possible urologic diagnoses that can lead to ANH and it is critical to recognize the patients who have ANH who require urgent or semiurgent evaluation soon after birth by a pediatric urologist and nephrologist. In addition, it is important to select appropriate postnatal imaging studies and to follow-up based on the clinical scenario and to prescribe prophylactic antibiotics to those patients most likely to benefit.