Renal ultrasound with Doppler in the diagnosis of acute pyelonephritis in children

Abstract

Objective: This study evaluates the diagnostic value of Renal Doppler Ultrasound (RDU) in the diagnosis of acute renal involvement among children admitted for a first febrile urinary tract infection (UTI), compared to a Renal Scintigraphy (RS). 

Methodology: All children admitted during 2009 for a first febrile UTI and positive urinary culture were prospectively studied. All received a RDU and RS with Tc99di-mercaptosuccinic acid during the first 72 hours of hospitalization. Image evaluation was performed blindly. RS was considered to be the gold standard to identify renal involvement. 

Results: The protocol was completed in 54 children (90%). RDU was altered in 36 (66%), and RS in 42 (78%) of children. Both exams coincided in 78% of the children, and in 81% of the kidneys. Sensitivity and specificity of RDU for these patients was 78,6% and 75% (72% and 89,6% per kidney), respectively. Negative predictive value was 50%. RDU detected significantly fewer defects in the left kidney, (p = 0,0026), especially if the defect was localized in the upper pole, and in absence of other associated scintigraphic abnormalities (p = 0,0001). Children with scintigraphic renal involvement showed significant more alterations during the acute phase. 

Conclusions: RDU is sensitive and specific to detect renal involvement in a child admitted for a febrile UTI, but has a low negative predictive value. Therefore, a negative ultrasound in a patient with inflammatory signs should be confirmed through a scintigraphy, since there are certain sites that are difficult to localize in a sonogram, such as the left superior pole.