Management of Recurrent UTI Symptoms with Negative Cultures and Low Urine pH

Diagnostic Approach

• The American College of Radiology recommends pelvic MRI as the first-line diagnostic test for recurrent UTI symptoms with negative cultures in a premenopausal woman, as it provides excellent soft-tissue contrast for evaluating urethral diverticula and has been shown to alter surgical management in 15% of patients 1
• Recurrent UTI symptoms with negative cultures in a young woman is a classic presentation of urethral diverticulum, which occurs in 30-50% of patients with this condition 1
• The combination of negative cultures with persistent symptoms should prompt evaluation for anatomical abnormalities rather than repeated empiric antibiotic treatment 1

Imaging Algorithm

• MRI is the optimal imaging modality for suspected urethral diverticulum, allowing for accurate diagnosis and improved surgical planning 1
• MRI is specifically preferred due to superior soft tissue contrast compared to CT urography 1
• Do not perform routine cystoscopy or extensive workup without first obtaining MRI in a woman under 40-50 years with recurrent UTI symptoms and no specific risk factors 2

If MRI is Negative: Consider Alternative Diagnoses

• If MRI shows no diverticulum, obtain urine culture and sensitivity testing during a symptomatic episode to guide antimicrobial therapy 1
• Common causative organisms include E. coli, Proteus mirabilis, Klebsiella, Enterococcus faecalis, and Staphylococcus saprophyticus 1
• Consider ultrasound to evaluate for hydronephrosis, postvoid residual volume, and incomplete bladder emptying 3, 2

Empiric Treatment While Awaiting Diagnosis

• Antimicrobial therapy options for acute symptom management include Nitrofurantoin 50-100 mg four times daily for 5 days, Trimethoprim-sulfamethoxazole 160/800 mg twice daily for 3 days, and Fosfomycin trometamol 3 g single dose 1, 4

Critical Pitfalls to Avoid

• Do not continue empiric antibiotic treatment without establishing a definitive diagnosis, as this leads to antimicrobial resistance and does not address the underlying anatomical problem 1
• Do not order CT urography instead of MRI for suspected urethral diverticulum, as MRI provides superior soft tissue visualization 1
• Do not perform invasive procedures (cystoscopy, ureteroscopy) without clear indication of complicated infection or first obtaining non-invasive imaging 2