From the Guidelines
A KUB ultrasound is not routinely necessary for patients with leukocyturia, hematuria, and suspected uncomplicated UTI. For most patients with typical UTI symptoms, diagnosis and treatment can proceed based on urinalysis and clinical presentation alone. Standard management includes empiric antibiotic therapy such as nitrofurantoin 100mg twice daily for 5 days, trimethoprim-sulfamethoxazole 160/800mg twice daily for 3 days, or fosfomycin 3g single dose, depending on local resistance patterns. However, imaging should be considered in specific situations:
- persistent symptoms despite appropriate antibiotic therapy
- recurrent UTIs (3 or more in 12 months)
- signs of complicated infection (fever, flank pain, or systemic symptoms)
- risk factors for anatomical abnormalities
- or in patients with immunocompromise. Ultrasound can detect complications like hydronephrosis, renal abscesses, or anatomical abnormalities that might contribute to infection. The rationale for selective imaging is that most uncomplicated UTIs resolve with appropriate antibiotic therapy, and routine imaging adds cost without changing management in most cases 1.
According to the most recent guidelines, the use of ultrasound in conjunction with a risk index (Hematuria Cancer Risk Score) may inform cystoscopy in hematuria patients, but cystoscopy is still the preferred recommendation for evaluation in intermediate- and high-risk patients 1. The goal of upper tract imaging in patients with hematuria is to identify malignancies of the renal parenchyma and upper tract urothelium as well as to identify actionable non-malignant diagnoses of the kidney, collecting system, and ureters.
In the context of the provided patient, with gross hematuria and suspected UTI, the decision to order a KUB ultrasound should be based on the presence of specific risk factors or complications, rather than routine practice. Given the low risk of upper tract malignancy in patients with microhematuria, as reported in studies such as those by Kang et al. and Samson et al., and the relatively low sensitivity of renal ultrasonography for detection of UTUC and renal cortical tumors, as noted in the study by Fankhauser et al., a more targeted approach to imaging is recommended 1.
Therefore, imaging with a KUB ultrasound should be reserved for patients with specific indications, such as those with persistent symptoms, recurrent infections, or risk factors for anatomical abnormalities, rather than being routinely ordered for all patients with leukocyturia, hematuria, and suspected UTI 1.
From the Research
Evaluation of Hematuria
The patient's presentation with gross hematuria, leukocyturia, and suspected urinary tract infection (UTI) requires a thorough evaluation to determine the underlying cause.
Imaging Studies
- CT urography is a recommended initial imaging test for hematuria in patients at high-risk for urothelial cell carcinoma (UCC) 2, 3.
- CT urography can evaluate the kidneys, ureters, and bladder, and has high diagnostic accuracy for UCC and other conditions such as renal cell cancer and stones.
- Ultrasound may not be the best initial imaging test for hematuria, as CT urography has been shown to be more effective in evaluating the urinary tract 2, 3.
Referral to Urology
- Referral to urology is recommended for all patients with gross hematuria or high-grade hematuria (>50 red blood cells per high-power field [RBCs/HPF]) on a single urinalysis (UA) 4.
- Patients with asymptomatic microscopic hematuria or symptomatic hematuria that produces >3 RBCs/HPF on two of three properly performed and collected urinalyses should also be referred to urology 4.
Current Practice Patterns
- Many primary care physicians do not fully evaluate patients with hematuria according to guidelines, with limited use of imaging, cystoscopy, and cytology 5, 6.
- Further studies are needed to determine the extent of the problem and impact on morbidity and survival 5.