Diagnostic accuracy of neonatal kidney ultrasound in children having antenatal hydronephrosis without ureter and bladder abnormalities.

PURPOSE

To determine the diagnostic accuracy of anteroposterior renal pelvic diameter (APD) measurement and the society for fetal urology (SFU) grading in neonatal ultrasonography (USG) for detecting uropathy in newborns having antenatal isolated hydronephrosis (IH), characterized by hydronephrosis without ureter and bladder abnormalities, and to study time to resolution and factors predicting resolution of insignificant hydronephrosis.

METHODS

Ninety-six healthy newborns (129 kidneys) with IH, who underwent USG at age 7-30 days and voiding cystourethrography (VCUG) in conjunction with diuretic renography (DR) if APD > 10 mm or SFU grade 3-4 in neonatal USG, and at least a 12-month follow-up were divided into significant and insignificant hydronephrosis using the combined data of sequential USG, VCUG, and DR as the reference standard.

RESULTS

Areas under the receiver operating characteristic plots (95 % CI) were 0.86 (0.79-0.94) versus 0.81 (0.73-0.89); p = 0.08, and 87.6 versus 79.8 % of cases were correctly classified, for APD ≥ 16 mm versus SFU grade 4, respectively. Ureteropelvic junction obstruction (UPJO) was the most common uropathy diagnosed. Of 85 kidneys with insignificant hydronephrosis, 57 underwent spontaneous resolution. The resolution rates were 24, 40, and 68 % at age 6, 12, and 24 months, respectively. APD was the only independent factor predicting resolution with the hazard ratio of 0.83 (95 % CI 0.74-0.92; p = 0.001).

CONCLUSIONS

In IH, neonatal USG was a useful diagnostic tool to detect uropathy, mainly UPJO. Further investigation should be recommended when APD ≥ 16 mm or SFU grade 4.