From the Guidelines
For a male with a history of kidney stones presenting with hematuria and non-infectious urine, the best initial imaging study is a non-contrast CT scan of the abdomen and pelvis (CT KUB - kidney, ureter, bladder). This recommendation is based on the most recent and highest quality study available, which emphasizes the importance of CT urography in evaluating hematuria, especially in patients with a history of kidney stones 1. The non-contrast technique is preferred because kidney stones are readily visible without contrast, and this approach avoids potential contrast-related complications.
Key Considerations
- The study should be performed promptly, especially if the patient is experiencing pain, as it can guide management decisions including whether urologic intervention is needed.
- While ultrasound is an alternative that avoids radiation exposure, it is less sensitive for detecting ureteral stones and provides less detailed anatomical information.
- In cases where radiation exposure is a significant concern (such as in young patients or those requiring repeated imaging), ultrasound may be considered as an initial approach, but CT remains the gold standard for evaluating suspected nephrolithiasis with hematuria.
- CT urography provides excellent delineation of the excretory urinary tract, is very sensitive for urinary stones, readily identifies renal cortical lesions, and provides extra-urinary information 1.
Imaging Modalities
- Non-contrast CT scan: highly sensitive and specific for detecting urinary stones, can identify size, location, and number of stones, and detects other potential causes of hematuria.
- Ultrasound: less sensitive for detecting ureteral stones, provides less detailed anatomical information, but avoids radiation exposure.
- CT urography: provides excellent delineation of the excretory urinary tract, sensitive for urinary stones, and identifies renal cortical lesions 1.
Clinical Context
- Patients with gross hematuria have a high association with malignancy, and all patients with gross hematuria should have a full urologic workup 1.
- Patients with microhematuria have a low risk of malignancy, but a cause is often never found 1.
- The choice of imaging is guided by the patient’s risk category, which seeks to balance diagnostic accuracy vs risk 1.
From the Research
Imaging Options for Hematuria in Males with a History of Kidney Stones
- Non-contrast computed tomography (CT) is considered the gold standard for diagnosing nephrolithiasis, as it provides accurate characterization of stone disease and helps direct therapy 2, 3.
- Ultrasound is also a useful imaging modality, particularly for follow-up, as it has lower radiation exposure compared to CT 2, 3.
- The choice of imaging modality may depend on the clinical presentation and patient factors, such as the presence of hematuria or a history of kidney stones 4, 5.
Factors Influencing Imaging Choice
- Stone size and presence of hematuria are significant factors in the diagnosis of nephrolithiasis, with larger stones and hematuria more likely to be associated with correct diagnosis 4.
- The location of the stone, such as in the renal pelvis, may also influence the choice of imaging modality and treatment outcome 5.
- Patient factors, such as radiation exposure concerns, may also influence the choice of imaging modality, with ultrasound being a lower-radiation alternative to CT 2, 6.
Special Considerations
- In patients with a history of kidney stones, imaging evaluation should aim to confirm the presence of a stone, assess its size and location, and rule out other causes of hematuria 4, 5.
- Non-contrast CT is particularly useful in this setting, as it provides detailed information about the stone and surrounding anatomy 2, 3.
- Ultrasound and other imaging modalities, such as MRI, may be used in special patient populations, such as pregnant women, or for follow-up evaluation 3.