Antenatal hydronephrosis: evaluation and outcome

Variation among pediatric urologists and across 2 continents in antibiotic prophylaxis and evaluation for prenatally detected hydronephrosis: a survey of American and European pediatric urologists

PURPOSE

No clear practice guidelines exist to evaluate prenatally diagnosed hydronephrosis or recommend antibiotic prophylaxis. We hypothesized that among pediatric urologists there is significant variability in prenatal hydronephrosis evaluation and management.

MATERIALS AND METHODS

We created a survey questionnaire to answer certain questions, including 1) what prenatal parameters trigger postnatal evaluation, 2) how pediatric urologists manage prenatal hydronephrosis and 3) what are their recommendations for antibiotic prophylaxis. Survey questions included demographics and practice patterns, and influences concerning radiographic tests and prophylactic antibiotics. A Web based survey link was sent to members of the Urology Section, American Academy of Pediatrics and the European Society for Pediatric Urology. We received 156 responses. We also compared practices based in Europe in 60 respondents and in the United States in 70.

RESULTS

There was significant response variability to all questions answered with no question achieving a consensus of more than 50%. European and American respondents were equally distributed in regard to years in practice and number of patients per month. Radiographic factors influenced the decision to perform further imaging or provide prophylactic antibiotics in around 50% of respondents. There was wide variability in parameters triggering intervention and in prophylactic antibiotics. Pediatric urologists in practice more than 15 years were less likely to prescribe antibiotic prophylaxis at birth than those in practice less than 15 years. Variation also existed by geographic region with American physicians more likely to prescribe antibiotics for any prenatal hydronephrosis compared to their European counterparts (77% vs 40%, p <0.005) and European physicians more likely to be influenced by prenatal pelvic diameter when obtaining postnatal imaging (unilateral 70% vs 47%, p = 0.009 and bilateral 55% vs 36%, p = 0.03, respectively). European pediatric urologists were also more likely to order renal scans than their American counterparts. These differences were less significant for high grade hydronephrosis.

CONCLUSIONS

Even among pediatric urologists there is considerable variation in radiographic resource and prophylactic antibiotics use when managing prenatal hydronephrosis. Some variation may be explained by regional differences but it is most probably due to absent clear guidelines based on prospective, randomized, controlled trials.

Antenatal hydronephrosis and the risk of pyelonephritis hospitalization during the first year of life

OBJECTIVES

To assess the risk of hospitalization for pyelonephritis within the first year of life among infants with and without antenatal hydronephrosis.

METHODS

A retrospective cohort analysis was performed using linked birth-hospital discharge records from Washington State for 1987 to 2002 to evaluate the risk of hospitalization in the first year of life for pyelonephritis among infants with and without hydronephrosis. Eligible infants had mothers who had prenatal ultrasound screening. A total of 522 singleton infants with antenatal hydronephrosis (International Classification of Diseases, Ninth Revision code 753.2) at the birth hospitalization were identified. For comparison, 2610 singletons without hydronephrosis were selected. We screened hospital discharge records for 1 year after delivery to identify hospitalizations for pyelonephritis and estimate the relative risk (RR) among infants with and without hydronephrosis.

RESULTS

Five percent of infants with antenatal hydronephrosis and 1% of those without had pyelonephritis-related hospitalizations in their first year (RR 11.8, 95% confidence interval [CI] 6.8 to 20.5). Among girls the RR was 36.3 (95% CI 10.6 to 124.0); among boys it was 5.3 (95% CI 2.2 to 13.1). In infants with hydronephrosis, girls were more likely to be hospitalized with pyelonephritis (odds ratio 2.9, 95% CI 1.2 to 6.9).

CONCLUSIONS

Infants with antenatal hydronephrosis are nearly 12 times more likely to have pyelonephritis-related hospitalizations in the first year of life. This association is stronger in girls. Parents and healthcare providers of infants with this diagnosis should be vigilant for the signs and symptoms of urinary tract infections.

Diagnostic accuracy of postnatal renal pelvic diameter as a predictor of uropathy: a prospective study

BACKGROUND

There is a necessity to standardize postnatal ultrasonographic markers predictive of significant uropathies. The purpose of this study was to assess the accuracy of anteroposterior renal pelvic diameter (APD) on postnatal ultrasound to discriminate between significant uropathy and idiopathic renal pelvic dilatation.

MATERIALS AND METHODS

Neonates ( n=110) who were found to have isolated fetal renal pelvic dilatation underwent systematic investigation and were prospectively followed up. A US scan was performed after the 1st week of life, and all infants underwent voiding cystourethrography. Neonates with an APD larger than 10 mm were examined with renal scintigraphy. Receiver-operating characteristic (ROC) plots were constructed to determine the best cutoffs for APD to identify renal units with significant uropathy as well as those requiring surgical intervention.

RESULTS

The area under the curve (AUC) estimated by the ROC curve was 0.921 (95% CI=0.869-0.957), indicating excellent discriminant power between nonsignificant pelvis dilatation and significant uropathy. A cutoff of 10 mm for APD showed the best accuracy for identifying infants with a significant uropathy (sensitivity, 90.4%; specificity, 91%). To identify infants who required surgical intervention, the calculated AUC was 0.976 (95% CI=0.940-0.993). A cutoff of 15 mm showed the best diagnostic performance for identifying the renal units requiring pyeloplasty (sensitivity, 100%; specificity, 92.5%).

CONCLUSION

Our results suggest that postnatal APD is an excellent test for identifying fetuses with significant uropathy, as well as those requiring postnatal intervention.