الفهرس 
Introduction
Definitions of urinary tract infectionOnly 14 pages are availabe for public view
 |  | from | 118 |  |  |
| | | from | 118 | | |
Abstract
The commonly used clinical and laboratory parameters are not reliable for the diagnosis of acute pyelonephritis. The presenting symptoms can be varied and sometimes confusing. Patients may present with fever, flank pain or tenderness, malaise, irritability, leukocytosis, and bacteriuria, but there may be no definite indication of renal parenchymal infection. Neonates in particular present with non-specific clinical findings. The higher grades of vesicoureteral reflux are generally associated with a greater risk for the development of pyelonephritis; however, acute pyelonephritis in the absence of vesicoureteral reflux is frequently seen.
The ultrasound (US) findings of pyelonephritis include an increase in renal parenchymal volume, focal or diffuse areas of abnormal parenchymal echogenicity (hypo- or hyperechoic foci) and loss of corticomedullary differentiation . The addition of power Doppler, which shows hypovascularity or absent flow in the affected area of the kidney, improves the detection rate of pyelonephritis with US.
Computed tomography has a similar sensitivity and specificity to cortical scanning for the detection of pyelonephritis , but adds to the risk of contrast reaction and has a higher radiation exposure. Its use is reserved for those children who fail to respond to antibacterial therapy, in whom the diagnosis remains in doubt. Computed tomography is also useful to further delineate complex inflammatory mass lesions seen on US, particularly when extrarenal extension of disease is suspected. Following IV contrast enhancement, images obtained in the nephrographic phase show sharply delineated areas of reduced attenuation. The lesions may be uni- or multifocal, and there may be poor corticomedullary differentiation.
Tc-99m DMSA
Renal cortical scintigraphy is used for the detection of the cortical defects of acute pyelonephritis and scarring related to chronic pyelonephritis. Cortical scintigraphy is able to detect twice as many defects as ultrasound and four times as many defects as intravenous urography. The loss of function associated with acute pyelonephritis, when detected early and satisfactorily treated, can be reversed without scar formation. The sequelae of renal infection can be monitored by follow-up cortical scintigraphy.
Tc-99m DMSA is an excellent cortical imaging agent. Approximately 40% of the Injected dose binds to the renal tubules within 1h after injection; the remainder is slowly excreted in the urine over the subsequent 24h. DMSA is used when high resolution anatomic images are required, such as the detection of pyelonephritis. Cortical scans can also confirm a suspected column of Bertin, measure relative function and identify functioning renal tissue in patients with congenital abnormalities. Renal cortical scintigraphy with Tc-99m DMSA is the standard method to detect pyelonephritis and cortical scarring.