What tests are used to diagnose cystitis and fistulization?

Diagnostic Testing for Cystitis and Fistulization

For diagnosing cystitis, a focused history of lower urinary tract symptoms and urine analysis are sufficient, while fistulization diagnosis requires advanced imaging such as CT cystography or contrast-enhanced CT with delayed scanning. 1

Cystitis Diagnostic Testing

Clinical Assessment

• Diagnosis of uncomplicated cystitis can be made with high probability based on a focused history of lower urinary tract symptoms (dysuria, frequency, urgency) and absence of vaginal discharge 1
• In elderly women, genitourinary symptoms are not necessarily related to cystitis and require more careful evaluation 1

Laboratory Testing

• In patients with typical symptoms of uncomplicated cystitis, urine analysis (dipstick testing) provides minimal increase in diagnostic accuracy but can help when diagnosis is unclear 1
• Urine culture is recommended only in specific situations:
  • Suspected acute pyelonephritis 1
  • Symptoms that do not resolve or recur within 4 weeks after treatment completion 1
  • Women presenting with atypical symptoms 1
  • Pregnant women 1, 2

Special Considerations

• For women whose symptoms don't resolve by end of treatment or recur within 2 weeks, urine culture and antimicrobial susceptibility testing should be performed 1
• In patients with high probability of UTI based on symptoms, negative dipstick urinalysis does not rule out infection 2
• Nitrites are likely more sensitive and specific than other dipstick components for UTI, particularly in elderly patients 2

Fistulization Diagnostic Testing

Imaging Studies

• CT cystography has supplanted fluoroscopic cystogram for diagnosing bladder fistulas and leaks 1
• Colovesical fistula can usually be diagnosed with contrast-enhanced CT based on:
  • Enhancing tract(s) with or without gas extending from colon to bladder wall 1
  • Associated focal bladder wall thickening 1
  • Presence of pneumaturia or fecaluria in clinical history 1

Advanced Imaging Options

• CT with rectal contrast or oral contrast with delayed scanning is useful to detect enterovesical fistulas and infected fistulous tracts 1
• CT cystography can provide additional information regarding size and location of colovesical fistula in presurgical planning 1
• MRI is equally sensitive to CT for evaluating vesicovaginal and enterovesicular fistulae with excellent soft-tissue contrast 1

Fluoroscopic Studies

• Fluoroscopic cystogram may be considered in specific circumstances for potential colovesical fistula:
  • When CT findings are ambiguous 1
  • For preoperative planning based on surgeon preference 1
  • However, CT has largely supplanted fluoroscopic cystography at most institutions 1

Diagnostic Algorithm

1. For uncomplicated cystitis:

   • Begin with clinical assessment of symptoms
   • If typical symptoms present, dipstick urinalysis may confirm diagnosis 1
   • Reserve urine culture for complicated cases or treatment failures 1

2. For suspected fistulization:

   • Contrast-enhanced CT with delayed images is first-line imaging 1
   • CT cystography for detailed evaluation of bladder involvement 1
   • Consider MRI when soft tissue detail is critical 1

Common Pitfalls to Avoid

• Overreliance on dipstick urinalysis alone to rule out UTI in symptomatic patients 2
• Failure to obtain urine culture in patients with recurrent or complicated UTIs 1
• Missing fistulas by not using appropriate contrast techniques during CT imaging 1
• Treating asymptomatic bacteriuria, which is common particularly in older women 2

By following this diagnostic approach, clinicians can accurately diagnose cystitis and identify fistulization when present, leading to appropriate treatment and improved patient outcomes.