What investigations are needed to rule out urosepsis?

Investigations to Rule Out Urosepsis

The essential investigations to rule out urosepsis include urinalysis, urine culture, blood cultures, and complete blood count with differential. 1

Initial Clinical Assessment

• Assess for symptoms and signs of urosepsis including fever, shaking chills, hypotension, and delirium, especially in the context of recent catheter obstruction or change 1
• Evaluate for UTI-associated symptoms such as dysuria, gross hematuria, and new or worsening urinary incontinence 1
• Monitor vital signs including temperature, heart rate, blood pressure, and respiratory rate to identify signs of systemic inflammatory response 1

Laboratory Investigations

Urinalysis

• Perform urinalysis for determination of leukocyte esterase and nitrite level by dipstick 1
• Conduct microscopic examination for white blood cells (WBCs) 1
• Pyuria is defined as ≥10 WBCs/high-power field or a positive leukocyte esterase test 1
• A negative urinalysis for WBCs and negative dipstick tests for leukocyte esterase and nitrite are useful to exclude a urinary source for suspected infection 1

Urine Culture

• Only order urine culture if pyuria is present or if there is strong clinical suspicion of urosepsis 1
• Obtain appropriately collected urine specimens:
  • For men: mid-stream or clean-catch specimen (if cooperative and functionally capable) or clean condom external collection system 1
  • For women: in-and-out catheterization is often required 1
  • For patients with indwelling catheters: change the catheter prior to specimen collection and before starting antibiotic therapy 1

Blood Tests

• Complete blood cell (CBC) count with differential should be performed within 12-24 hours of symptom onset 1
• Pay particular attention to:
  • Elevated WBC count (≥14,000 cells/mm³) 1
  • Left shift (percentage of band neutrophils ≥16% or total band neutrophil count ≥1,500 cells/mm³) 1
  • These findings warrant careful assessment for bacterial infection even without fever 1

Blood Cultures

• If urosepsis is suspected, obtain paired blood and urine specimens for culture and antimicrobial susceptibility testing 1
• Request Gram stain of uncentrifuged urine 1
• While blood cultures may have low yield in long-term care facilities, they are essential in suspected urosepsis to guide appropriate antimicrobial therapy 2, 3

Imaging Studies

• Consider imaging studies if there is:
  • Suspected urinary tract obstruction 4, 5
  • Failure to respond to appropriate antimicrobial therapy within 72 hours 1
  • Deterioration in clinical status despite treatment 1, 5
• Ultrasound is the preferred initial imaging modality to rule out obstruction or stone disease 1, 4
• Consider advanced imaging (CT scan) for patients with persistent fever or clinical deterioration 1, 5

Special Considerations

• For patients with indwelling catheters, evaluation is indicated if there is suspected urosepsis (fever, shaking chills, hypotension, or delirium), especially in the context of recent catheter obstruction or change 1
• Elderly patients are at higher risk for urosepsis, particularly those over 60 years of age and those with prolonged catheterization 6
• In the absence of fever, leukocytosis, left shift, or specific clinical manifestations of focal infection, additional diagnostic tests may not be indicated due to low potential yield 1

Common Pitfalls to Avoid

• Do not perform urinalysis and urine cultures for asymptomatic patients 1
• Avoid attributing nonspecific symptoms (confusion, anorexia, functional decline) to UTI without specific urinary symptoms 1
• Remember that bacteriuria is common in elderly patients and does not necessarily indicate infection requiring treatment 1
• Do not collect urine specimens from drainage bags of catheterized patients; obtain specimens by aspiration of the catheter port 1