Objective: To assess the ability of ultrasonography to identify reflux nephropathy in children after urinary tract infection.
Design: Ten experienced radiologists performed a total of 240 ultrasonographic examinations of kidneys in a one day study. The examiners were unaware of the results of previous radiological and clinical examinations and of the proportions of normal and abnormal kidneys. Urography was used as method of reference, supported by static renal scintigraphy (dimercaptosuccinic acid labelled with technetium-99m) in half of the cases.
Setting: Outpatient radiology department.
Subjects: 25 children aged 2-16 years (20 kidneys with and 30 kidneys without renal scarring).
Main outcome measures: Renal scarring. Overall size and length of kidneys. Sensitivity and specificity including receiver operator characteristics and variation between observers.
Results: With renal scarring as the diagnostic criterion and including cases classified as abnormal, probably abnormal, and uncertain the sensitivity of ultrasonography was 54% (specificity 80%). Addition of reduced renal size as a diagnostic criterion increased the sensitivity to 64% (specificity 79%). There were, however, wide variations between observers, with sensitivity ranging between 40% and 90% (specificity 94% to 65%).
Conclusions: Because of its low sensitivity and specificity and poor agreement between observers, ultrasonography cannot be generally recommended for the detection of reflux nephropathy after urinary tract infection in children.