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.


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%).


CONCLUSIONS
Our results suggest that postnatal APD is an excellent test for identifying fetuses with significant uropathy, as well as those requiring postnatal intervention.
Neonatal Unit, Department of Pediatrics, Hospital das Clínicas, Federal University of Minas Gerais, Avenida Professor Alfredo Balena 190, 30130-100, Belo Horizonte, Brazil.
Maria Cândida Ferrarez
MC
Bouzada
Eduardo Araujo
EA
Oliveira
Alamanda Kfoury
AK
Pereira
Henrique Vitor
HV
Leite
Andréia Moura
AM
Rodrigues
Lívia Alvarenga
LA
Fagundes
Ricardo Peixoto
RP
Gonçalves
Ricardo
R
Parreiras
D001837:Body Weights and Measures; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007674:Kidney Diseases / Q000000981:diagnostic imaging*; D007682:Kidney Pelvis / Q000000981:diagnostic imaging*; D008297:Male; D011181:Postnatal Care; D011237:Predictive Value of Tests; D011446:Prospective Studies; D014463:Ultrasonography / Q000379:methods*