Objective: Antenatal hydronephrosis is diagnosed in 1-5% of all pregnancies; however the antenatal and postnatal management of hydronephrosis varies widely. No previous studies define the risk of postnatal pathology in infants with antenatal hydronephrosis. Our objective is to systematically review and synthesize data from the current literature to determine whether or not the degree of antenatal hydronephrosis and related antenatal ultrasound findings are associated with postnatal outcome.
Methods: We searched Medline (1966-2005), Embase (1991-2004) and the Cochrane Library databases for articles on antenatal hydronephrosis published in the English language. We required studies to have subjects selected based on documented measurements of antenatal hydronephrosis and followed to a postnatal diagnosis. We excluded case reports, review articles, and editorials. Two independent investigators extracted data, which included demographics, antenatal and postnatal ultrasound variables, postnatal diagnoses and patient outcome.
Results: We screened 1,645 citations of which 17 studies met inclusion criteria. We created a data set of 1,308 subjects. The risk of any postnatal pathology per degree of antenatal hydronephrosis was 11.9% (95% CI 4.5 - 28.0) for mild, 45.1% (25.3 - 66.6) for moderate, and 88.3% (53.7 - 98.0) for severe. There was a significant increase in risk per increasing degree of hydronephrosis (p<0.001). The risk of vesicoureteral reflux was similar for all degrees of antenatal hydronephrosis (p=0.10).
Conclusions: The findings of this meta-analysis can potentially be used for prenatal counseling and may alter current postnatal management of children with ANH. Overall, children with any degree of ANH are at greater risk of postnatal pathology as compared to the normal population. Moderate and severe ANH have a significant risk of postnatal pathology indicating that comprehensive postnatal diagnostic management should be performed. Mild ANH may carry a risk for postnatal pathology but further prospective studies are needed to determine the optimal management of these children. To further define the risk of pathology and the appropriate management protocols for different degrees of hydronephrosis, a well-defined prospective analysis of the relationship between the parameters of prenatal ultrasound needs to be performed.