PRESENTATION AND DIAGNOSIS

In addition to the symptoms associated with cystitis (see Plate 5-2), which may or may not be present, acute pyelonephritis features high fever, anorexia, nausea/vomiting, costovertebral angle tenderness, and flank, abdominal, or pelvic pain. Patients with severe disease may have concurrent septic shock and multiorgan failure. Older patients may have altered mental status. Acute kidney injury does not usually occur in pyelonephritis unless there is concomitant obstruction or shock.

As in cystitis, urinalysis should be positive for leukocyte esterase, indicating the presence of white blood cells, and nitrites, indicating the presence of bacteria. Proteinuria (of up to 2 g/day) may also be noted. On urine microscopy, white blood cell casts may be seen in addition to white blood cells and bacteria.

A complete blood count with differential may reveal leukocytosis with neutrophilia. In some cases, serum chemistries may reveal azotemia or electrolyte abnormalities secondary to dehydration.

Urine culture and at least two sets of blood cultures should be obtained before initiation of antibiotic therapy to determine if there is concurrent bacteremia.

In the absence of acute kidney injury or urinary tract obstruction, radiologic studies do not need to be pursued at the outset. In patients who fail to defervesce after 48 to 72 hours of treatment with appropriate antibiotics, however, a renal ultrasound or computed tomography (CT) scan of the abdomen and pelvis may be performed. In uncomplicated pyelonephritis, Ultrasonography is usually normal, whereas a CT scan may reveal perinephric stranding and patchy areas of diminished, inhomogeneous enhancement. The presence of an abscess, gas collection, or obstruction indicates complicated pyelonephritis.