In patients with recurrent ascending urinary tract infections, it may be necessary to exclude an anatomical abnormality, such as vesicoureteral reflux or polycystic kidney disease. Investigations used in this setting include kidney ultrasonography or voiding cystourethrography. CT scan or kidney ultrasonography is useful in the diagnosis of xanthogranulomatous pyelonephritis; serial imaging may be useful for differentiating this condition from kidney cancer. Ultrasound findings that indicate pyelonephritis are enlargement of the kidney, edema in the renal sinus or parenchyma, bleeding, loss of corticomedullary differentiation, abscess formation, or an areas of poor blood flow on doppler ultrasound. However, ultrasound findings are seen in only 20% to 24% of people with pyelonephritis.A DMSA scan is a radionuclide scan that uses dimercaptosuccinic acid in assessing the kidney morphology. It is now the most reliable test for the diagnosis of acute pyelonephritis. Classification
Acute pyelonephritis
Acute pyelonephritis is an exudative purulent localized inflammation of the renal pelvis (collecting system) and kidney. The kidney parenchyma presents in the interstitium abscesses (suppurative necrosis), consisting in purulent exudate (pus): neutrophils, fibrin, cell debris and central germ colonies (hematoxylinophils). Tubules are damaged by exudate and may contain neutrophil casts. In the early stages, the glomerulus and vessels are normal. Gross pathology often reveals pathognomonic radiations of bleeding and suppuration through the renal pelvis to the renal cortex. Chronic pyelonephritis
Chronic pyelonephritis implies recurrent kidney infections and can result in scarring of the renal parenchyma and impaired function, especially in the setting of obstruction.
The visual field data suggests that there is a higher incidence of end arteriolar distribution infarction and a higher incidence of permanent visual field defects in retinal migraine than in clinically manifest cerebral infarctions in migraine with aura. A 2005 study suggests that more than half of reported recurrent cases of retinal migraine subsequently experienced permanent visual loss in that eye from infarcts, but later studies suggest such loss is a relatively rare side effect. See also
Entoptic phenomenon
Scintillating scotoma

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