Avoiding contrast-enhanced computed tomography scans in patients with shellfish allergies.

The “Things We Do for No Reason” (TWDFNR) series reviews practices which have become common parts of hospital care but which may provide little value to our patients. Practices reviewed in the TWDFNR series do not represent “black and white” conclusions or clinical practice standards, but are meant as a starting place for research and active discussions among hospitalists and patients. We invite you to be part of that discussion. A 55-year-old patient with a history of chronic obstructive pulmonary disease and diabetes mellitus presented to the emergency room with acute shortness of breath and right leg swelling that began 1 week after lumbar disk surgery. The emergency department team decides against ordering a chest CT scan with contrast to evaluate for a possible pulmonary embolism after noting that the patient’s allergies include shellfish, which cause urticaria and facial edema. A ventilationperfusion scan reveals heterogeneous perfusion defects consistent with an intermediate probability (20%– 80%) for pulmonary embolism. The treating physicians consider starting the patient on a steroid regimen to prepare him for a CT scan with IV contrast, while presumptively anticoagulating the patient for 24 hours in order for the steroids to provide maximal protective effect before obtaining the scan. Should a history of shellfish allergy affect decision making regarding whether to administer IV contrast?