In the outpatient setting, pyelonephritis is usually suggested by a patient’s history and physical examination and supported by urinalysis results. Urine specimens can be collected through the following methods:
Clean catch
Urethral catheterization
Suprapubic needle aspiration
Urinalysis can include the following:
Dipstick leukocyte esterase test (LET) - Helps to screen for pyuria
Nitrite production test (NPT) - To screen for bacteriuria
Examination for hematuria (gross and microscopic) and proteinuria
Urine culture is indicated in any patient with pyelonephritis, whether treated in an inpatient or outpatient setting, because of the possibility of antibiotic resistance.
Imaging studies that may be used in assessing acute pyelonephritis include the following:
Computed tomography (CT) scanning - To identify alterations in renal parenchymal perfusion; alterations in contrast excretion, perinephric fluid, and nonrenal disease; gas-forming infections; hemorrhage; inflammatory masses; and obstruction
Magnetic resonance imaging (MRI) – To detect renal infection or masses and urinary obstruction, as well as to evaluate renal vasculature
Ultrasonography - To screen for urinary obstruction in children admitted for febrile illnesses and to examine patients for renal abscesses, acute focal bacterial nephritis, and stones (in xanthogranulomatous pyelonephritis)
Scintigraphy - To detect focal renal abnormalities
CT and MR urography - Used in the evaluation of hematuria