A 45 y/o F presents to the Emergency Department with a 1-day history of severe L ear pain radiating to her jaw. She tells you she was recently swimming in a lake. There is no discharge from the ear. Her past medical history includes hypertension, diabetes, and a remote appendectomy. She is otherwise healthy. Her only medication is Amlodipine. There is no trismus or cranial nerve findings. Your examination findings are consistent with Otitis Externa. You consider Malignant Otitis Externa given the severity of her pain and her history of diabetes. What blood test is MOST appropriate to rule in Malignant Otitis Externa if pretest probability is LOW?

About the Author: Anton Helman

Dr. Anton Helman is an Emergency Physician at North York General in Toronto. He is an Assistant Professor at the University of Toronto, Division of Emergency Medicine and the Education Innovation Lead at the Schwartz-Reisman Emergency Medicine Instititute. He is the founder, editor-in-chief and host of Emergency Medicine Cases.