Emergency physicians are accustomed to routinely obtaining CT scans to evaluate many types of patients in daily practice, including those with abdominal pain, neurological complaints, and chest pain. However, we are often faced with particular patients where the ordering of a CT scan is not straightforward and even potentially harmful for the patient. This chapter focuses on some of those circumstances common in everyday practice. The first section reviews the renal effects of radiological contrast media and pretreatment options in the patient with underlying renal insufficiency. Next, a systematic approach to the patient who has a history of a reaction to contrast is discussed. Finally, because a patient receives significantly more radiation with a CT scan than a plain x-ray, we review some guidelines for ordering diagnostic imaging and CT scans in pregnant patients.

RADIOGRAPHIC CONTRAST-INDUCED NEPHROPATHY

Radiographic contrast-induced nephropathy (RCIN) is a significant complication in at-risk patients who receive IV contrast dye. RCIN is the third most common cause of hospital-acquired renal failure, after surgery and hypotension (1). RCIN is associated with prolonged hospitalizations, with up to a 36% in-hospital mortality and 19% 2-year survival (2–4).

Because creatinine clearance measurements (glomerular filtration rates) are not practical or cost effective due to time constraints in an acute care setting, isolated serum creatinine levels are used to measure renal function.