What are the recommendations for the use of CT scanning in the diagnosis of nephrolithiasis?

Updated: Jun 21, 2018
  • Author: Chirag N Dave, MD; Chief Editor: Bradley Fields Schwartz, DO, FACS  more...
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Answer

In current clinical practice, the renal colic noncontrast CT scan is the standard of care in most EDs when a patient is thought to have renal colic or presents with acute flank pain. Guidelines from the American College of Radiology (ACR) recommend noncontrast CT as the most appropriate radiologic procedure for both suspected stone disease and recurrent symptoms of stone disease. Reduced-dose techniques are preferred. [39]

Because of the limitations of CT scans, some urologists request additional studies, such as KUB radiography or IVP, to help them make critical decisions about management, follow-up, and possible surgical interventions. In cases of suspected stone disease in pregnant patients and in patients allergic to iodinated contrast or when noncontrast CT is unavailable, the ACR considers ultrasonography of the kidney and bladder retroperitoneal with Doppler and KUB the preferred examination. [39]

As noted earlier, obtaining a KUB radiograph when a renal colic CT scan study is performed for acute flank pain provides more precise information about the size and shape of any stone and quickly reveals whether stones are nonopaque and radiolucent. Follow-up evaluations are easier because only a repeat KUB radiograph is needed for comparison. A KUB radiograph also helps the urologist determine if a stone will be visible on fluoroscopic images, which is useful for possible shockwave lithotripsy since for most lithotripters used in the United States, fluoroscopic visualization is needed for stone targeting and positioning.

While the addition of an abdominal flat plate study (KUB radiograph) adds to the overall financial cost and requires additional time, the extra information the study provides is often quite valuable and ultimately beneficial to the patient. If the stone is visible on the CT scout image, however, then this provides the same information as a KUB and thus the latter is not needed.


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