What imaging studies are recommended for patients with recurrent Urinary Tract Infections (UTIs)?

Imaging for Recurrent Urinary Tract Infections

Imaging studies are not routinely recommended for patients with uncomplicated recurrent UTIs but should be performed in patients with complicated UTIs, including those who are nonresponders to conventional therapy, develop frequent reinfections or relapses, or have known underlying risk factors. 1

Uncomplicated Recurrent UTIs

For patients with uncomplicated recurrent UTIs (defined as three or more symptomatic infections over a 12-month period) without underlying risk factors:

• No imaging studies are routinely recommended as most women with recurrent uncomplicated UTIs have normal urinary tracts 1
• Current clinical guidelines indicate that imaging should not be routinely obtained due to the low yield of anatomic abnormalities 1
• Prior studies have demonstrated a low yield of non-incidental findings in patients with a low pretest probability of complicated UTI 1

Complicated Recurrent UTIs

Imaging should be considered in patients with:

• Nonresponse to conventional therapy 1
• Frequent reinfections or relapses (particularly infections recurring within 2 weeks of treatment) 1
• Known underlying risk factors 1
• Hematuria (gross hematuria or persistent microscopic hematuria between infections) 2
• Pyelonephritis 2
• Atypical presentation (obstructive symptoms, infection with urea-splitting bacteria, clinical impression of persistent infection) 2
• Suspected urinary calculi 2

Recommended Imaging Studies for Complicated UTIs

First-Line Imaging:

• CT Urography (CTU) is the primary recommended test for evaluation of recurrent complicated UTIs 1
  • Includes unenhanced, nephrographic phase, and excretory phase images
  • Provides detailed anatomic depiction of the urinary tract including kidneys, collecting systems, ureters, and bladder
  • Excellent sensitivity and specificity for identification of renal and urothelial lesions 1
  • Useful for detecting or excluding congenital anomalies or obstruction 1

Alternative Imaging Options:

• Ultrasound of kidneys, bladder, and retroperitoneum

  • May be useful as an initial screening tool in complicated cases 3
  • Particularly valuable for diagnosing pyonephrosis 4
  • Non-invasive and does not involve radiation exposure

• CT Pelvis with Bladder Contrast (CT Cystography)

  • Useful for diagnosing bladder fistulas and leaks 1
  • Has supplanted fluoroscopic cystogram for evaluation of traumatic bladder injuries 1

• MR Urography (MRU)

  • Alternative to CTU in patients with contraindications to CT or iodinated contrast 1
  • Has supplanted intravenous urography (IVU) at most institutions 1

Important Considerations and Caveats

• Historically used imaging techniques such as intravenous urography (IVU) are no longer recommended or used at most institutions 1
• Standard contrast-enhanced CT of the abdomen and pelvis (without specific urographic protocol) is not optimally tailored for evaluation of the urothelium 1
• Diabetes alone does not warrant urologic evaluation 2
• In patients with suspected upper tract infection who do not respond promptly to treatment, CT is the study of choice for diagnostic evaluation 4
• For patients with suspected pyonephrosis, ultrasound may be more easily performed for initial diagnosis 4

Clinical Pearls

• The most threatening conditions that imaging aims to detect are obstruction of an infected upper tract and abscesses of the genitourinary system 3
• Causes of bacterial persistence that may be identified on imaging include calculi, foreign bodies, urethral or bladder diverticula, infected urachal cyst, and postoperative changes 1
• Non-E. coli UTIs are associated with higher rates of imaging abnormalities and recurrent infections 5