What are the differences in urinalysis to distinguish between cystitis and pyelonephritis?

From the Guidelines

Urinalysis can help distinguish between cystitis and pyelonephritis by identifying key differences in the presence of white blood cell casts, pyuria, and bacteriuria, with pyelonephritis typically showing more significant findings and the presence of white blood cell casts being pathognomonic for kidney involvement 1.

Key Differences in Urinalysis

• Pyuria (white blood cells) and bacteriuria are present in both conditions, but pyelonephritis tends to show more significant pyuria and bacteriuria 1
• White blood cell casts are typically present in pyelonephritis, indicating kidney involvement, and are rarely seen in cystitis 1
• Microscopic hematuria may be present in both conditions, but is more common in cystitis 1
• Nitrites may be positive in both conditions when caused by gram-negative bacteria 1
• The pH is typically alkaline in infections caused by urease-producing organisms like Proteus 1

Clinical Presentation and Diagnosis

• Clinical presentation remains crucial for accurate diagnosis, as pyelonephritis represents a more serious infection involving the kidney parenchyma, while cystitis affects only the bladder mucosa 1
• Systemic signs like fever and flank pain are more common in pyelonephritis, and laboratory tests often reveal elevated inflammatory markers (leukocytosis, elevated C-reactive protein, and erythrocyte sedimentation rate) 1
• The presence of white blood cell casts in urinalysis, combined with clinical presentation and laboratory findings, can help distinguish between cystitis and pyelonephritis 1

From the Research

Differences in Urinalysis

• The presence of pyuria (and possibly indirect quantitation of pyuria by the leukocyte esterase test) is a reliable indicator of treatable infection, and its absence indicates infection is not present 2
• Urine culture is of clear value only in patients with acute pyelonephritis or subclinical pyelonephritis 2
• Urinalysis is also of great value in symptomatic patients 2

Cystitis vs Pyelonephritis

• Cystitis symptoms include lower abdominal pain, dysuria, and urinary urgency or frequency 3
• Pyelonephritis presents with costovertebral tenderness, fever, and urinary symptoms 3
• The distinction between cystitis and pyelonephritis is made primarily from clinical findings 2
• Urine culture is recommended for the diagnosis and management of pyelonephritis, recurrent urinary tract infection, and complicated urinary tract infections 4

Laboratory Tests

• Primary laboratory tests for UTIs consist of urinalysis and urine culture 5
• Urine culture with antimicrobial susceptibility testing should be performed in all patients with pyelonephritis and used to direct therapy 6
• Imaging, blood cultures, and measurement of serum inflammatory markers should not be performed in uncomplicated cases of pyelonephritis 6

Treatment

• Nitrofurantoin, fosfomycin, and trimethoprim-sulfamethoxazole are first-line therapies for acute uncomplicated cystitis 5
• Third-generation cephalosporins are preferred for management of pyelonephritis 3
• Fluoroquinolones and trimethoprim/sulfamethoxazole are effective oral antibiotics in most cases of pyelonephritis, but increasing resistance makes empiric use problematic 6