Investigations for acute pyelonephritis in adults

Obtain a midstream urine sample for microscopy, culture and susceptibility testing from adults with suspected acute pyelonephritis before starting antibioticsNational Institute for Health and Care Excellence (NICE), October 2018. The diagnosis of acute pyelonephritis is unlikely if pyuria is absent on urine microscopy.

Collect blood samples for culture and susceptibility testing before starting antibiotics for patients with acute pyelonephritis who require intravenous antibiotics or hospitalisation.

Consider imaging (computed tomography [CT] with contrast, or renal ultrasound) if symptoms suggest kidney and ureteric stones (eg loin pain, haematuria) and to exclude urinary obstruction or renal abscess if the patient remains febrile after 72 hours of appropriate antibiotic treatmentBonkat, 2024.

Consider urological evaluation for males with acute pyelonephritis.

Do not perform post-treatment urine culture to confirm resolution of infection for asymptomatic patients, except for pregnant patients and those with acute bacterial prostatitis.