What imaging is needed for a patient with a Foley catheter (Foley catheter) who develops urinary retention with hematuria while on a course of antibiotics (CBI - Community-acquired bacterial infection treatment, e.g. Ciprofloxacin)?

Imaging for Patients with Foley Catheter, Urinary Retention, and Hematuria

For patients with a Foley catheter who develop urinary retention with hematuria requiring continuous bladder irrigation (CBI), upper tract imaging should be performed if the patient has a febrile urinary tract infection that doesn't respond to antibiotics or if the patient is at moderate/high risk for urologic complications. 1

Risk Assessment and Indications for Imaging

Immediate Imaging Indications:

• Febrile UTI not responding to appropriate antibiotic therapy 1
• Gross hematuria with pelvic fracture (requires retrograde cystography) 1
• Suspected trauma with gross hematuria (requires CT urography) 1

Risk-Based Imaging Approach:

• Moderate-risk patients: Upper tract imaging every 1-2 years 1
• High-risk patients: Annual upper tract imaging 1
• Even if patients respond to antibiotics, appropriate radiographic assessment is still required in moderate/high-risk patients 1

Imaging Modality Selection

First-Line Imaging:

• CT Urography: Preferred initial imaging for gross hematuria (sensitivity 92%, specificity 93%) 2, 3
  • Best for detecting stones, renal/perirenal infections, and complications 1
  • Should include contrast enhancement unless contraindicated 1

Alternative Imaging Options:

• Ultrasound: Alternative when CT is contraindicated (sensitivity 50%, specificity 95%) 2, 3

  • Less sensitive than CT but useful for initial screening 3
  • Limited sensitivity for detecting renal injuries (41% diagnostic accuracy) 1

• MR Urography: For patients with contrast allergy or renal insufficiency 2

  • Similar diagnostic accuracy to CT for complicated UTIs except for calculi 4

Special Considerations

For Trauma Patients:

• Retrograde cystography (plain film or CT) is mandatory for patients with gross hematuria and pelvic fracture 1
• CT cystogram requires retrograde distention of bladder with minimum 300mL contrast 1
• Simply clamping a Foley catheter to allow excreted IV contrast to accumulate is inadequate 1

For Recurrent UTIs:

• Evaluate both upper and lower urinary tracts with imaging and cystoscopy 1
• Consider urodynamic evaluation if upper and lower tract evaluations are unremarkable 1

Practical Approach

1. Obtain urine culture after changing the catheter and allowing for urine accumulation 1
2. For patients with febrile UTI, order upper tract imaging if:
   • Patient doesn't respond to antibiotics, OR
   • Patient is moderate/high-risk and not up to date with routine imaging 1
3. For patients with gross hematuria, CT urography is the preferred imaging modality 2
4. For patients with suspected bladder injury, perform retrograde cystography 1

Common Pitfalls to Avoid

• Relying solely on ultrasound for trauma patients with gross hematuria (may miss injuries) 1
• Using inadequate contrast volume for cystography (minimum 300mL needed) 1
• Collecting urine samples from extension tubing or collection bag (obtain after changing catheter) 1
• Assuming microscopic hematuria in catheterized patients always requires imaging (risk stratification needed) 2

By following these evidence-based recommendations, appropriate imaging can be selected to evaluate patients with Foley catheters who develop urinary retention with hematuria requiring CBI.