Resistive Index (RI) in Febrile Urinary Tract Infection: New Predictive Value

Abstract

Background and Objective: Urinary tract infection is the most common bacterial infection in the pediatric population.The upper urinary tract infection involves the kidney parenchyma and may cause scarring and permanent damage that will proceed to cause hypertension and decreased kidney function. Almost third of cases will relapse following the first infection in one year. There are different imaging techniques that can help to detect children at risk for future infections, kidney scarring or other systemic complications. The Ultrasonography of bladder and kidneys: is a relatively cheap, non-invasive and fast test that enables to find children with anatomical anomalies that can be corrected to avoid future infections or complications. Also, this test does not pose the risk of radiation exposure. Voiding cystourethrogram: is the test of choice to establish the presence of vesicoureteral reflux that is a major risk factor for future infections and scaring. This test has a radiation exposure risk, it is invasive and relatively complex to perform. DMSA scintigraphy test: may be performed to determine acute pyelonephritis or to investigate kidney scarring. This test has a greater radiation exposure risk. But it cannot distinguish between dysplasia of a kidney or scarring. With the development and improvement of the imaging capabilities of Doppler ultrasonography, we can measure the Resistive Index, which is a sonographic value to assess the kidney function. The normal value of the resistive index is 0.6 and the normal upper limit is 0.7. The increase in this value is related to kidney artery stenosis, extreme hypertension, infants, and intrinsic kidney disease. Importance: In this work, we want to measure if the Resistive Index can predict kidney scarring. Participants: We followed after 71 cases of kids from 0 to 11 years old that was admitted to our hospital Baruch Padeh Medical Center, Poriya, in the diagnosis of Urinary tract infection.71 children participated in the full evaluation. 56 children were under 2 years of age, 8 were aged 2 to 4 years, and 7 were over 5 years or older; 18 were males and 53 were females. Design: The diagnosis was made on the base of clinical presentation, laboratory blood analysis, urinary analysis, and urinary cultures. We measured the Resistive index in all of these patients. And they did the ordinary US of kidney parenchyma, the DMSA study and a cystography by the accepted protocols of our department. Settings: All patients underwent Doppler within 72 hours of hospitalization. Before our conclusions, we divided the patients in the study by their age. Main outcome: In the first group under 2 years old, we found a moderate correlation between the RI and DMSA study. And there was a strong correlation between RI and cystography .In the second group above 4 years, we found a strong correlation between RI both to DMSA and cystography. Results: In all the age groups we examined there is a strong correlation between RI and positive findings in cystography to find reflux.