What is the appropriate workup for a patient with recurrent sterile pyuria?

Workup for Recurrent Sterile Pyuria

The appropriate workup for recurrent sterile pyuria should include urine culture to confirm diagnosis, evaluation of upper and lower urinary tracts with imaging and cystoscopy, and urodynamic studies if initial evaluation is unremarkable.

Initial Diagnostic Steps

• Confirm the presence of pyuria with urinalysis, defined as ≥8 WBC/high-power field on manual microscopy or ≥10 WBC/mm³ using a hemocytometer 1
• Obtain urine culture during symptomatic episodes to confirm sterility (absence of conventional bacterial growth) 2
• Ensure proper collection technique when obtaining urine specimens, especially in catheterized patients 2
• Consider changing indwelling catheters before obtaining specimens to avoid contamination 2

Evaluation for Structural Abnormalities

• Perform upper tract imaging (ultrasound, CT urography, or MRI) to evaluate for stones, hydronephrosis, or other structural abnormalities 2
• Consider cystoscopy to evaluate the lower urinary tract for abnormalities such as urethral diverticula, fistulas, or other structural issues 2
• CT urography (CTU) is the primary test for evaluation of complicated recurrent UTIs as it provides detailed anatomic depiction of the urinary tract 2

Special Considerations

• Evaluate for incomplete bladder emptying with post-void residual measurement 3
• Consider specialized cultures for fastidious organisms not detected by conventional methods, such as Ureaplasma urealyticum, which can cause sterile pyuria and urinary stones 4
• Assess for systemic conditions that can cause sterile pyuria, such as:
  • Chronic kidney disease (CKD), which increases the prevalence of asymptomatic pyuria 5
  • Autoimmune conditions like systemic lupus erythematosus (SLE), where isolated pyuria may indicate active disease 6

Advanced Testing

• Perform urodynamic studies in patients with recurrent urinary tract infections and an unremarkable evaluation of the upper and lower urinary tract 2
• Consider fluoroscopic voiding cystourethrography if vesicoureteral reflux is suspected, though this is not routinely required for uncomplicated cases 2

Management Approach

• Avoid treating asymptomatic bacteriuria in patients with neurogenic lower urinary tract dysfunction (NLUTD) to prevent antibiotic resistance 2
• For postmenopausal women, consider vaginal estrogen with or without lactobacillus-containing probiotics 2
• For recurrent UTIs associated with sexual activity in premenopausal women, consider low-dose post-coital antibiotics 2
• Consider immunoactive prophylaxis, methenamine hippurate, or hyaluronic acid instillations for prevention when appropriate 2

Common Pitfalls to Avoid

• Avoid classifying patients with recurrent UTIs as "complicated" unless they have structural/functional abnormalities, immune suppression, or pregnancy, as this often leads to unnecessary use of broad-spectrum antibiotics 2
• Do not perform routine post-treatment urinalysis or urine cultures in asymptomatic patients 2
• Avoid treating asymptomatic bacteriuria, as this fosters antimicrobial resistance and may increase recurrent UTI episodes 2