Imaging of renal trauma.
Because of complex variables and unsettled treatment issues, a standardized prescription for imaging the acutely traumatized kidney cannot be written. Imaging considerations are based on treatment considerations and will vary from place to place, from patient to patient, from physician to physician, and even from time to time in the same institution. The condition of the patient, the availability of resources and personnel, and (especially) whether existing treatment policy is conservative or aggressive will govern the selection of studies. Above all, since the kidney may be only one of several organs requiring immediate investigation, it is always the totality of the situation that sets the tone for the imaging process. A synthesis of prevailing thought is depicted diagrammatically in Figure 2 and is summarized as follows: CT is the most informative radiologic study in renal trauma and is the examination of choice in patients suspected of having serious renal injuries or associated injuries amenable to CT evaluation. CT is wasteful, however, in the stable, asymptomatic patient who is perceived to have only a minor, exclusively renal injury. Here, excretory urography is an acceptable alternative. Most of these patients will have normal findings at urography, all but ruling out significant renal damage. The vast majority of patients will fall into this category but for those whose urograms do not provide adequate information for management, CT is performed next. Sonography and radionuclide imaging, while advocated in some quarters, do not enjoy wide acceptance in the United States as first-line triage studies. They are usually reserved for selected situations, mainly for follow-up. Arteriography still has a place, primarily in preoperative road mapping, and for therapeutic interventions such as embolization of bleeding vessels and arteriovenous fistulas. The role of MR imaging has yet to be defined. The choice of imaging in renal trauma requires discretion, judgement, and common sense. Standard protocols are useful, but there is a place for flexibility and the customizing of individual approaches.