Doppler ultrasonography in children with acute pyelonephritis in diagnosis of renal scar compared to DMSA scintigraphy

Urinary tract infection (UTI) is one of the most important pediatric health problems, which is occasionally associated with irreversible renal damage. Dimercapto-succinic acid (DMSA) scan is a diagnostic standard for the renal scar. Doppler ultrasonography (D.S) has been considered as a less invasive method. The purpose of this study was to determine the sensitivity and specificity of D.S in the diagnosis of renal scarring in children with a history of acute pyelonephritis (APN).

The present cross-sectional study was conducted on 120 children with APN, aged six months to twelve years in the University Pediatric Hospital of Qazvin, Iran, between August 2017 and August 2018. DMSA scan was performed in the acute phase of pyelonephritis for all patients. Half of the children with acute pyelonephritis had decreased radionuclide uptake in the first DMSA scan of whom thirty patients had kidney scarring in the second scan, six months later. Then renal vascular D.S was performed for these patients. Simultaneously, twenty children with a normal DMSA scan, assigned for D.S.

The mean age of children was 5.30(3.50-11.8), and 4.80(2.50-10.09) in the scar and control group. Most of the patients in both groups were female, 25(83.8%) in renal scar, and 15(75.0%) in control. The scar group showed a greater rate of vesicoureteral reflux, 17(56.6%), of whom 11(36.7%) were bilateral. Among 30 patients with a renal scar, 2(6.7%) had first-time acute pyelonephritis, 11(36.7%) had second, and 17(56.7%) had more than two attacks of pyelonephritis. The frequency of renal scarring was 25% based on DMSA scan and 14% based on D.S. Accordingly, the sensitivity and specificity of D.S in the detection of renal scarring in children with APN was 23.3% and 100%.

Doppler ultrasonography is not a suitable method for diagnosis of renal scarring in children, due to the low sensitivity and negative predictive value of this device in the detection of renal scarring in children with UTI. However, normal Doppler sonography can predict that the patient did not have a kidney scar.