PATIENT EVALUATION: Laboratory and Imaging Studies

Abstract

The evaluation of urolithiases, in terms of calculus detection and evaluation of the morphology and function of the kidneys, continues to be refined with advances in imaging technology. The most significant recent advance is use of helical or spiral CT scan for the accurate delineation of renal and ureteral calculi in the acute setting. This may provide an accurate, rapid, and cost-effective method of patient evaluation. The alternative approach is to use plain abdominal radiography to detect renal or ureteral calculi. Noncontrast-enhanced helical or spiral CT scanning has its greatest impact in patients with negative abdominal radiographs or in those patients with suspected urinary colic in whom renal but not ureteral calculi are seen. A supplemental intravenous urogram can be used, as appropriate, to evaluate renal function and degree of obstruction on both the involved and uninvolved side. Combined abdominal radiography and sonography may be used for calculus detection and demonstration of obstruction. Sonography is an operator-dependent technique requiring expertise, experience, and adequate imaging equipment for satisfactory results. Physiologic study of renal blood flow and urinary dynamics using Doppler techniques are possible, though considered to be in the realm of clinical investigation at this time. Sonography has a valuable role in the serial evaluation of chronic stone formers with a history of recurrent urinary infections related to obstruction or reflux. Radiography, fluoroscopy, and sonography are the imaging, methods used in ESWL treatment in preprocedure and postprocedure.