Kidney length and scarring in children with urinary tract infection: importance of ultrasound scans.

BACKGROUND

Many studies have demonstrated that dimercaptosuccinic acid (DMSA) scintigraphy is the most sensitive diagnostic method in the identification of irreversible renal lesions (scars) in children with previous episodes of acute pyelonephritis (APN). This study assessed the reliability of ultrasound in identifying reflux nephropathy in children with acute pyelonephritis with or without vesicoureteric reflux (VUR).

METHODS

Eighty children (45 female and 35 male, age range 5 months to 10 years, average age 2 years 1 month) with a positive history for at least one episode of APN participated in this study. All children underwent voiding cystourethrography, DMSA scintigraphy 4 to 8 months after the most recent episode of APN, and an ultrasound test evaluation less than 2 months after DMSA scintigraphy.

RESULTS

Voiding cystourethrograms showed VUR in 52 children (68%); 13 of these were bilateral, for a total of 65 refluxing kidney units of the 154 (42%) evaluated; DMSA scintigram was normal for 108 of 154 kidneys (70%). Of the 65 kidneys with VUR, DMSA scintigram displayed normal findings in 29 cases (45%) and pathologic findings in 36 (55%). In the 79 nonrefluxing kidneys, DMSA scintigram was normal in 69 cases (87%). The relative risk of scarring in VUR kidneys is 2.6. The ultrasound study recorded a maximum longitudinal diameter between the 5th and 95th percentiles in 80 of 89 (81%) kidneys without VUR and in 21 of 65 (32%) with VUR. A significant correlation was found between maximum longitudinal diameters and DMSA scintigraphic findings in kidneys with VUR and those without VUR, respectively.

CONCLUSION

This study establishes that ultrasound scans, by means of a simple and reproducible measurement technique, maximum longitudinal diameter, have a predictive value with regard to the presence of scars, with few exceptions. This finding, in our opinion, could lead to a decrease in the number of invasive procedures, in particular DMSA scan, in patients with APN.